Most outdated models cordless screwdrivers was equipped with NiCd batteries. As everyone knows, these batteries do not produce a lot of power; moreover, they have a “memory” effect, due to which the capacity volume is significantly reduced. Therefore, many owners of such equipment take up the task of converting screwdrivers to 12V 18650 lithium batteries. The process is labor-intensive, but if you follow the steps, the result will be crowned with success.

Pros and cons of modernization

Before converting a screwdriver to 18650 lithium batteries, you need to understand what the master will get as a result. The advantages of these manipulations are as follows:

• multiple increase in screwdriver operating time;
• increasing the speed of battery charging - for a full supply of energy for lithium batteries, approximately 1 hour is needed;
• increasing the charging current power to 1-2 C;
• reduction of costs for the regular purchase of new NiCd batteries due to their insufficient service life;
• The complete absence of memory effect in lithium batteries.

Also, before converting the battery with your own hands to a more modern technology, you should be aware of the negative consequences:

• it is necessary to connect a controller to determine the charge level, since the device cannot be charged more than 4.2 V and discharged less than 2.7 V;
• lithium-ion batteries for screwdrivers of the Li-lon series lose their capabilities when used in low temperature conditions;
• when converting a screwdriver to a lithium battery, difficulties may arise with adapting the charger from NiCd; here you will have to use a universal device.

Preparatory moments

First of all, you should determine the maximum voltage value. For this purpose, it is necessary to calculate the number of elements. For three parts, the most acceptable value is 12 Volts, for 4 parts - 16 V.

Take a screwdriver battery with a maximum voltage of 14.4 V as a basis. In this case, it is recommended to use 4 cells. This will not only equalize the difference in volts, but also increase the capacitance. It turns out that lithium battery-powered screwdrivers can work much longer.

As for the type of batteries, experts recommend giving preference to the 18650 series; it is the most optimal option. Next you need to figure out the capacity and discharge current. During normal operation of the device, the current consumption level varies within 5-10 Am. But if an unexpected sharp descent occurs, the value rises to 25 Am. In order not to harm the battery during such a drop, it is recommended to select elements with increased value discharge current, for example, up to 30 Am.

Instead of four lithium ion cans, eight can be used. But for this you need to fasten 2 elements in parallel. Next, the connecting pairs must be connected in series. It is important to consider here that not all battery cases can accommodate 8 parts at the same time.

The controller must be selected according to the rated voltage, as well as taking into account the discharge current. These values ​​must match. More precisely, the voltage will be completely the same for both the battery and the controller, but only the operating discharge current must be 2 times less than the limit.

Using an example, it looks like this - the charging-discharging control device is designed for 13-14 Am, while the protective function will turn on when the current sharply increases to 30 Am.

Even when converting a screwdriver to lithium, it is necessary to take into account the dimensions of the protective board, since it must completely fit into the equipment body. Otherwise, you need to use your imagination to increase the body part. It is strictly not recommended to leave this part open.

Step-by-step instruction

Once all the components and tools for replacing the batteries in the screwdriver are prepared, you can begin assembly. As an example, the conversion of 12 volt equipment to a Li-lon battery was disassembled, inside which there were 12 NiCd battery cans of 1.2 V each.

1. First of all, you need to dismantle the case and remove the built-in battery from it. This requires wire cutters because the connector itself must remain in place.
2. Take the controller device and thermocouple. These elements must be installed in the area where the temperature sensor was. By the way, if this part has not yet been removed, it should be removed. You also need to remember that you need to select all the parts so that they can fit into the tool body.

1. After this, solder all prepared parts in strict sequence. Solder the controller to the board according to the selected circuit. The main thing here is not to forget to connect the balancing points. For this purpose, the diagram has a special connector and wiring.
2. The final stage is connecting the output to the pole and minus.
3. The main part of the work is done, now all that remains is to carefully assemble everything into the case without damaging anything.

If the kit included a standard charger, then there will be no problems with them. Such devices are quite suitable for lithium battery packs. All the charge will also be supplied through the controller, which completely eliminates the possibility of battery overheating from power surges.

Many people wonder if it is possible to make a charger that will charge two types of batteries? Circuits for such devices exist, and they work, but using such a charger is not recommended due to the difference in voltage between the battery packs.

New battery packs on the market sell for an average of about 2000-3000 rubles. And the cost of upgrading nickel-cadmium to lithium-ion does not exceed 1000 rubles. Therefore, the rework is completely justified.

VIDEO: How to transfer a screwdriver to lithium batteries (welding batteries into a battery)

Assessing the characteristics of a particular charger is difficult without understanding how an exemplary charge of a li-ion battery should actually proceed. Therefore, before moving directly to the diagrams, let's remember a little theory.

What are lithium batteries?

Depending on what material the positive electrode of a lithium battery is made of, there are several varieties:

• with lithium cobaltate cathode;
• with a cathode based on lithiated iron phosphate;
• based on nickel-cobalt-aluminium;
• based on nickel-cobalt-manganese.

All of these batteries have their own characteristics, but since these nuances are not of fundamental importance for the general consumer, they will not be considered in this article.

Also, all li-ion batteries are produced in various sizes and form factors. They can be either cased (for example, the popular 18650 today) or laminated or prismatic (gel-polymer batteries). The latter are hermetically sealed bags made of a special film, which contain electrodes and electrode mass.

The most common sizes of li-ion batteries are shown in the table below (all of them have a nominal voltage of 3.7 volts):

Internal electrochemical processes proceed in the same way and do not depend on the form factor and design of the battery, so everything said below applies equally to all lithium batteries.

How to properly charge lithium-ion batteries

The most correct way to charge lithium batteries is to charge in two stages. This is the method Sony uses in all of its chargers. Despite a more complex charge controller, this ensures a more complete charge of li-ion batteries without reducing their service life.

Here we are talking about a two-stage charge profile for lithium batteries, abbreviated as CC/CV (constant current, constant voltage). There are also options with pulse and step currents, but they are not discussed in this article. You can read more about charging with pulsed current.

So, let's look at both stages of charging in more detail.

1. At the first stage A constant charging current must be ensured. The current value is 0.2-0.5C. For accelerated charging, it is allowed to increase the current to 0.5-1.0C (where C is the battery capacity).

For example, for a battery with a capacity of 3000 mAh, the nominal charge current at the first stage is 600-1500 mA, and the accelerated charge current can be in the range of 1.5-3A.

To ensure constant charging current given value, the charger circuit must be able to increase the voltage at the battery terminals. In fact, at the first stage the charger works as a classic current stabilizer.

Important: If you plan to charge batteries with a built-in protection board (PCB), then when designing the charger circuit you need to make sure that the open circuit voltage of the circuit can never exceed 6-7 volts. Otherwise, the protection board may be damaged.

At the moment when the voltage on the battery rises to 4.2 volts, the battery will gain approximately 70-80% of its capacity (the specific capacity value will depend on the charging current: with accelerated charging it will be a little less, with a nominal charge - a little more). This moment marks the end of the first stage of charging and serves as a signal for the transition to the second (and final) stage.

2. Second charge stage- this is charging the battery with a constant voltage, but a gradually decreasing (falling) current.

At this stage, the charger maintains a voltage of 4.15-4.25 volts on the battery and controls the current value.

As the capacity increases, the charging current will decrease. As soon as its value decreases to 0.05-0.01C, the charging process is considered complete.

An important nuance of the operation of a proper charger is its complete shutdown from the battery after charging is completed. This is due to the fact that for lithium batteries it is extremely undesirable for them to remain under increased voltage, which usually provides the charger (i.e. 4.18-4.24 volts). This leads to accelerated degradation chemical composition battery and, as a result, a decrease in its capacity. Long-term stay means tens of hours or more.

During the second stage of charging, the battery manages to gain approximately 0.1-0.15 more of its capacity. The total battery charge thus reaches 90-95%, which is an excellent indicator.

We looked at two main stages of charging. However, coverage of the issue of charging lithium batteries would be incomplete if another charging stage were not mentioned - the so-called. precharge.

Preliminary charge stage (precharge)- this stage is used only for deeply discharged batteries (below 2.5 V) to bring them to normal operating mode.

At this stage, the charge is provided with a reduced constant current until the battery voltage reaches 2.8 V.

The preliminary stage is necessary to prevent swelling and depressurization (or even explosion with fire) of damaged batteries, which have, for example, internal short circuit between the electrodes. If a large charge current is immediately passed through such a battery, this will inevitably lead to its heating, and then it depends.

Another benefit of precharging is pre-warming the battery, which is important when charging at low temperatures environment (in an unheated room during the cold season).

Intelligent charging should be able to monitor the voltage on the battery during the preliminary charging stage and, if the voltage does not rise for a long time, draw a conclusion that the battery is faulty.

All stages of charging a lithium-ion battery (including the pre-charge stage) are schematically depicted in this graph:

Exceeding nominal charging voltage by 0.15V can reduce battery life by half. Lowering the charge voltage by 0.1 volt reduces the capacity of a charged battery by about 10%, but significantly extends its service life. The voltage of a fully charged battery after removing it from the charger is 4.1-4.15 volts.

Let me summarize the above and outline the main points:

1. What current should I use to charge a li-ion battery (for example, 18650 or any other)?

The current will depend on how quickly you would like to charge it and can range from 0.2C to 1C.

For example, for a battery size 18650 with a capacity of 3400 mAh, the minimum charge current is 680 mA, and the maximum is 3400 mA.

2. How long does it take to charge, for example, the same 18650 batteries?

The charging time directly depends on the charging current and is calculated using the formula:

T = C / I charge.

For example, the charging time of our 3400 mAh battery with a current of 1A will be about 3.5 hours.

3. How to properly charge a lithium polymer battery?

All lithium batteries charge the same way. It doesn't matter whether it is lithium polymer or lithium ion. For us, consumers, there is no difference.

What is a protection board?

The protection board (or PCB - power control board) is designed to protect against short circuit, overcharge and overdischarge of the lithium battery. As a rule, overheating protection is also built into the protection modules.

For safety reasons, it is prohibited to use lithium batteries in household appliances unless they have a built-in protection board. That's why all cell phone batteries always have a PCB board. The battery output terminals are located directly on the board:

These boards use a six-legged charge controller on a specialized device (JW01, JW11, K091, G2J, G3J, S8210, S8261, NE57600 and other analogues). The task of this controller is to disconnect the battery from the load when the battery is completely discharged and disconnect the battery from charging when it reaches 4.25V.

Here, for example, is a diagram of the BP-6M battery protection board that was supplied with old Nokia phones:

If we talk about 18650, they can be produced either with or without a protection board. The protection module is located near the negative terminal of the battery.

The board increases the length of the battery by 2-3 mm.

Batteries without a PCB module are usually included in batteries that come with their own protection circuits.

Any battery with protection can easily turn into a battery without protection; you just need to gut it.

Today, the maximum capacity of the 18650 battery is 3400 mAh. Batteries with protection must have a corresponding designation on the case ("Protected").

Do not confuse the PCB board with the PCM module (PCM - power charge module). If the former serve only the purpose of protecting the battery, then the latter are designed to control the charging process - they limit the charge current at a given level, control the temperature and, in general, ensure the entire process. The PCM board is what we call a charge controller.

I hope now there are no questions left, how to charge an 18650 battery or any other lithium battery? Then we move on to a small selection of ready-made circuit solutions chargers(the same charge controllers).

Charging schemes for li-ion batteries

All circuits are suitable for charging any lithium battery; all that remains is to decide on the charging current and the element base.

LM317

Diagram of a simple charger based on the LM317 chip with a charge indicator:

The circuit is the simplest, the whole setup comes down to setting the output voltage to 4.2 volts using trim resistor R8 (without a connected battery!) and setting the charging current by selecting resistors R4, R6. The power of resistor R1 is at least 1 Watt.

As soon as the LED goes out, the charging process can be considered completed (the charging current will never decrease to zero). It is not recommended to keep the battery on this charge for a long time after it is fully charged.

The lm317 microcircuit is widely used in various voltage and current stabilizers (depending on the connection circuit). It is sold on every corner and costs pennies (you can take 10 pieces for only 55 rubles).

LM317 comes in different housings:

Pin assignment (pinout):

Analogues of the LM317 chip are: GL317, SG31, SG317, UC317T, ECG1900, LM31MDT, SP900, KR142EN12, KR1157EN1 (the last two are domestically produced).

The charging current can be increased to 3A if you take LM350 instead of LM317. It will, however, be more expensive - 11 rubles/piece.

The printed circuit board and circuit assembly are shown below:

The old Soviet transistor KT361 can be replaced with a similar pnp transistor (for example, KT3107, KT3108 or bourgeois 2N5086, 2SA733, BC308A). It can be removed altogether if the charge indicator is not needed.

Disadvantage of the circuit: the supply voltage must be in the range of 8-12V. This is due to the fact that for normal operation LM317 microcircuit, the difference between the battery voltage and the supply voltage must be at least 4.25 Volts. Thus, it will not be possible to power it from the USB port.

MAX1555 or MAX1551

MAX1551/MAX1555 are specialized chargers for Li+ batteries, capable of operating from USB or from a separate power adapter (for example, a phone charger).

The only difference between these microcircuits is that MAX1555 produces a signal to indicate the charging process, and MAX1551 produces a signal that the power is on. Those. 1555 is still preferable in most cases, so 1551 is now difficult to find on sale.

A detailed description of these microcircuits from the manufacturer is.

The maximum input voltage from the DC adapter is 7 V, when powered by USB - 6 V. When the supply voltage drops to 3.52 V, the microcircuit turns off and charging stops.

The microcircuit itself detects at which input the supply voltage is present and connects to it. If the power is supplied via the USB bus, then maximum current The charge is limited to 100 mA - this allows you to plug the charger into the USB port of any computer without fear of burning the south bridge.

When powered by a separate power supply, the typical charging current is 280 mA.

The chips have built-in overheating protection. But even in this case, the circuit continues to operate, reducing the charge current by 17 mA for each degree above 110 ° C.

There is a pre-charge function (see above): as long as the battery voltage is below 3V, the microcircuit limits the charge current to 40 mA.

The microcircuit has 5 pins. Here is a typical connection diagram:

If there is a guarantee that the voltage at the output of your adapter cannot under any circumstances exceed 7 volts, then you can do without the 7805 stabilizer.

The USB charging option can be assembled, for example, on this one.

The microcircuit does not require either external diodes or external transistors. In general, of course, gorgeous little things! Only they are too small and inconvenient to solder. And they are also expensive ().

LP2951

The LP2951 stabilizer is manufactured by National Semiconductors (). It provides the implementation of a built-in current limiting function and allows you to generate a stable charge voltage level for a lithium-ion battery at the output of the circuit.

The charge voltage is 4.08 - 4.26 volts and is set by resistor R3 when the battery is disconnected. The voltage is kept very precisely.

The charge current is 150 - 300mA, this value is limited by the internal circuits of the LP2951 chip (depending on the manufacturer).

Use the diode with a small reverse current. For example, it can be any of the 1N400X series that you can purchase. The diode is used as a blocking diode to prevent reverse current from the battery to the LP2951 chip when the input voltage is turned off.

This charger produces a fairly low charging current, so any 18650 battery can charge overnight.

The microcircuit can be purchased both in a DIP package and in a SOIC package (costs about 10 rubles per piece).

MCP73831

The chip allows you to create the right chargers, and it’s also cheaper than the much-hyped MAX1555.

A typical connection diagram is taken from:

An important advantage of the circuit is the absence of low-resistance powerful resistors that limit the charge current. Here the current is set by a resistor connected to the 5th pin of the microcircuit. Its resistance should be in the range of 2-10 kOhm.

The assembled charger looks like this:

The microcircuit heats up quite well during operation, but this does not seem to bother it. It fulfills its function.

Here is another version of a printed circuit board with an SMD LED and a micro-USB connector:

LTC4054 (STC4054)

Very simple scheme, great option! Allows charging with current up to 800 mA (see). True, it tends to get very hot, but in this case the built-in overheating protection reduces the current.

The circuit can be significantly simplified by throwing out one or even both LEDs with a transistor. Then it will look like this (you must admit, it couldn’t be simpler: a couple of resistors and one condenser):

One of the printed circuit board options is available at . The board is designed for elements of standard size 0805.

I=1000/R. You shouldn’t set a high current right away; first see how hot the microcircuit gets. For my purposes, I took a 2.7 kOhm resistor, and the charge current turned out to be about 360 mA.

It is unlikely that it will be possible to adapt a radiator to this microcircuit, and it is not a fact that it will be effective due to the high thermal resistance of the crystal-case junction. The manufacturer recommends making the heat sink “through the leads” - making the traces as thick as possible and leaving the foil under the chip body. In general, the more “earth” foil left, the better.

By the way, most of the heat is dissipated through the 3rd leg, so you can make this trace very wide and thick (fill it with excess solder).

The LTC4054 chip package may be labeled LTH7 or LTADY.

LTH7 differs from LTADY in that the first can lift a very low battery (on which the voltage is less than 2.9 volts), while the second cannot (you need to swing it separately).

The chip turned out to be very successful, so it has a bunch of analogues: STC4054, MCP73831, TB4054, QX4054, TP4054, SGM4054, ACE4054, LP4054, U4054, BL4054, WPM4054, IT4504, Y1880, PT6102, PT6181, VS6102 , HX6001, LC6000, LN5060, CX9058, EC49016, CYT5026, Q7051. Before using any of the analogues, check the datasheets.

TP4056

The microcircuit is made in a SOP-8 housing (see), it has a metal heat sink on its belly that is not connected to the contacts, which allows for more efficient heat removal. Allows you to charge the battery with a current of up to 1A (the current depends on the current-setting resistor).

The connection diagram requires the bare minimum of hanging elements:

The circuit implements the classical charging process - first charging with a constant current, then with a constant voltage and a falling current. Everything is scientific. If you look at charging step by step, you can distinguish several stages:

1. Monitoring the voltage of the connected battery (this happens all the time).
2. Precharge phase (if the battery is discharged below 2.9 V). Charge with a current of 1/10 from the one programmed by the resistor R prog (100 mA at R prog = 1.2 kOhm) to a level of 2.9 V.
3. Charging with a maximum constant current (1000 mA at R prog = 1.2 kOhm);
4. When the battery reaches 4.2 V, the voltage on the battery is fixed at this level. Begins smooth decline charging current.
5. When the current reaches 1/10 of the one programmed by the resistor R prog (100 mA at R prog = 1.2 kOhm), the charger turns off.
6. After charging is complete, the controller continues monitoring the battery voltage (see point 1). The current consumed by the monitoring circuit is 2-3 µA. After the voltage drops to 4.0V, charging starts again. And so on in a circle.

The charge current (in amperes) is calculated by the formula I=1200/R prog. The permissible maximum is 1000 mA.

A real charging test with a 3400 mAh 18650 battery is shown in the graph:

The advantage of the microcircuit is that the charge current is set by just one resistor. Powerful low-resistance resistors are not required. Plus there is an indicator of the charging process, as well as an indication of the end of charging. When the battery is not connected, the indicator blinks every few seconds.

The supply voltage of the circuit should be within 4.5...8 volts. The closer to 4.5V, the better (so the chip heats up less).

The first leg is used to connect a temperature sensor built into the lithium-ion battery (usually the middle terminal of a cell phone battery). If the output voltage is below 45% or above 80% of the supply voltage, charging is suspended. If you don't need temperature control, just plant that foot on the ground.

Attention! This circuit has one significant drawback: the absence of a battery reverse polarity protection circuit. In this case, the controller is guaranteed to burn out due to exceeding the maximum current. In this case, the supply voltage of the circuit directly goes to the battery, which is very dangerous.

The signet is simple and can be done in an hour on your knee. If time is of the essence, you can order ready-made modules. Some manufacturers of ready-made modules add protection against overcurrent and overdischarge (for example, you can choose which board you need - with or without protection, and with which connector).

You can also find ready-made boards with a contact for a temperature sensor. Or even a charging module with several parallel TP4056 microcircuits to increase the charging current and with reverse polarity protection (example).

LTC1734

Also a very simple scheme. The charging current is set by resistor R prog (for example, if you install a 3 kOhm resistor, the current will be 500 mA).

Microcircuits are usually marked on the case: LTRG (they can often be found in old Samsung phones).

Any pnp transistor is suitable, the main thing is that it is designed for a given charging current.

There is no charge indicator on the indicated diagram, but on the LTC1734 it is said that pin “4” (Prog) has two functions - setting the current and monitoring the end of the battery charge. For example, a circuit with control of the end of charge using the LT1716 comparator is shown.

The LT1716 comparator in this case can be replaced with a cheap LM358.

TL431 + transistor

It is probably difficult to come up with a circuit using more affordable components. The most difficult thing here is to find the TL431 reference voltage source. But they are so common that they are found almost everywhere (rarely does a power source do without this microcircuit).

Well, the TIP41 transistor can be replaced with any other one with a suitable collector current. Even the old Soviet KT819, KT805 (or less powerful KT815, KT817) will do.

Setting up the circuit comes down to setting the output voltage (without a battery!!!) using a trim resistor at 4.2 volts. Resistor R1 sets the maximum value of the charging current.

This circuit fully implements the two-stage process of charging lithium batteries - first charging with direct current, then moving to the voltage stabilization phase and smoothly reducing the current to almost zero. The only drawback is the poor repeatability of the circuit (it is capricious in setup and demanding on the components used).

MCP73812

There is another undeservedly neglected microcircuit from Microchip - MCP73812 (see). Based on it, a very budget charging option is obtained (and inexpensive!). The whole body kit is just one resistor!

By the way, the microcircuit is made in a solder-friendly package - SOT23-5.

The only negative is that it gets very hot and there is no charge indication. It also somehow doesn’t work very reliably if you have a low-power power source (which causes a voltage drop).

In general, if the charge indication is not important for you, and a current of 500 mA suits you, then the MCP73812 is a very good option.

NCP1835

A fully integrated solution is offered - NCP1835B, providing high stability of the charging voltage (4.2 ±0.05 V).

Perhaps the only drawback of this microcircuit is its too miniature size (DFN-10 case, size 3x3 mm). Not everyone can provide high-quality soldering of such miniature elements.

Among the undeniable advantages I would like to note the following:

1. Minimum number of body parts.
2. Possibility of charging a completely discharged battery (precharge current 30 mA);
3. Determining the end of charging.
4. Programmable charging current - up to 1000 mA.
5. Charge and error indication (capable of detecting non-chargeable batteries and signaling this).
6. Protection against long-term charging (by changing the capacitance of the capacitor C t, you can set the maximum charging time from 6.6 to 784 minutes).

The cost of the microcircuit is not exactly cheap, but also not so high (~$1) that you can refuse to use it. If you are comfortable with a soldering iron, I would recommend choosing this option.

More detailed description is in .

Can I charge a lithium-ion battery without a controller?

Yes, you can. However, this will require close control of the charging current and voltage.

In general, it will not be possible to charge a battery, for example, our 18650, without a charger. You still need to somehow limit the maximum charge current, so at least the most primitive memory will still be required.

The simplest charger for any lithium battery is a resistor connected in series with the battery:

The resistance and power dissipation of the resistor depend on the voltage of the power source that will be used for charging.

As an example, let's calculate a resistor for a 5 Volt power supply. We will charge an 18650 battery with a capacity of 2400 mAh.

So, at the very beginning of charging, the voltage drop across the resistor will be:

U r = 5 - 2.8 = 2.2 Volts

Let's say our 5V power supply is rated for a maximum current of 1A. The circuit will consume the highest current at the very beginning of the charge, when the voltage on the battery is minimal and amounts to 2.7-2.8 Volts.

Attention: these calculations do not take into account the possibility that the battery may be very deeply discharged and the voltage on it may be much lower, even to zero.

Thus, the resistor resistance required to limit the current at the very beginning of the charge at 1 Ampere should be:

R = U / I = 2.2 / 1 = 2.2 Ohm

Resistor power dissipation:

P r = I 2 R = 1*1*2.2 = 2.2 W

At the very end of the battery charge, when the voltage on it approaches 4.2 V, the charge current will be:

I charge = (U ip - 4.2) / R = (5 - 4.2) / 2.2 = 0.3 A

That is, as we see, all values ​​do not go beyond the permissible limits for a given battery: the initial current does not exceed the maximum permissible charging current for a given battery (2.4 A), and the final current exceeds the current at which the battery no longer gains capacity ( 0.24 A).

The main disadvantage of such charging is the need to constantly monitor the voltage on the battery. And manually turn off the charge as soon as the voltage reaches 4.2 Volts. The fact is that lithium batteries tolerate even short-term overvoltage very poorly - the electrode masses begin to quickly degrade, which inevitably leads to loss of capacity. At the same time, all the prerequisites for overheating and depressurization are created.

If your battery has a built-in protection board, which was discussed just above, then everything becomes simpler. When a certain voltage is reached on the battery, the board itself will disconnect it from the charger. However, this charging method has significant disadvantages, which we discussed in.

The protection built into the battery will not allow it to be overcharged under any circumstances. All you have to do is control the charge current so that it does not exceed the permissible values ​​for a given battery (protection boards cannot limit the charge current, unfortunately).

Charging using a laboratory power supply

If you have a power supply with current protection (limitation), then you are saved! Such a power source is already a full-fledged charger that implements the correct charge profile, which we wrote about above (CC/CV).

All you need to do to charge li-ion is set the power supply to 4.2 volts and set the desired current limit. And you can connect the battery.

At first, when the battery is still discharged, laboratory block power supply will operate in current protection mode (i.e. it will stabilize the output current at a given level). Then, when the voltage on the bank rises to the set 4.2V, the power supply will switch to voltage stabilization mode, and the current will begin to drop.

When the current drops to 0.05-0.1C, the battery can be considered fully charged.

As you can see, the laboratory power supply is an almost ideal charger! The only thing it can’t do automatically is make a decision to fully charge the battery and turn off. But this is a small thing that you shouldn’t even pay attention to.

How to charge lithium batteries?

And if we are talking about a disposable battery that is not intended for recharging, then the correct (and only correct) answer to this question is NO.

The fact is that any lithium battery (for example, the common CR2032 in the form of a flat tablet) is characterized by the presence of an internal passivating layer that covers the lithium anode. This layer prevents chemical reaction anode with electrolyte. And the supply of external current destroys the above protective layer, leading to damage to the battery.

By the way, if we talk about the non-rechargeable CR2032 battery, then the LIR2032, which is very similar to it, is already a full-fledged battery. It can and should be charged. Only its voltage is not 3, but 3.6V.

How to charge lithium batteries (be it a phone battery, 18650 or any other li-ion battery) was discussed at the beginning of the article.

Converting a screwdriver battery to lithium cells

Many owners of screwdrivers want to convert their batteries to lithium battery cells. Many articles have been written on this topic, and in this material I would like to summarize the information on this issue. First of all, let's look at the arguments in favor of converting a screwdriver to lithium batteries and against it. We will also consider individual aspects of the battery replacement process itself.

First you need to think, do I need this alteration? After all, this will be an outright “homemade” and in some cases can lead to failure of both the battery and the screwdriver itself. Therefore, let's look at the pros and cons of this procedure. It is possible that after this some of you will decide to abandon the conversion of Ni─Cd to lithium cells.

Pros

Let's start with the advantages:

• The energy density of lithium-ion elements is significantly higher than that of nickel-cadmium elements, which are used by default in screwdrivers. That is, a lithium battery will have less weight than a cadmium battery with the same capacity and output voltage;
• Charging of lithium battery cells occurs much faster than in the case of Ni─Cd. It will take about an hour to charge them safely;
• In lithium─ ion batteries there is no “memory effect”. This means that they do not need to be completely discharged before charging..

Now about the shortcomings and difficulties.

Cons

• Lithium battery cells cannot be charged above 4.2 volts and discharged below 2.7 volts. In real conditions, this interval is even narrower. If you go beyond these limits, the battery can be damaged. Therefore, in addition to the lithium cans themselves, you will need to connect and install a charge-discharge controller in the screwdriver;
• The voltage of one Li─Ion element is 3.6─3.7 volts, and for Ni─Cd and Ni─MH this value is 1.2 volts. That is, there are problems with the assembly battery for screwdrivers with a voltage rating of 12 volts. From three lithium cans connected in series, you can assemble a battery with a nominal value of 11.1 volts. Out of four ─ 14.8, out of five ─ 18.5 volts and so on. Naturally, the voltage limits during charge-discharge will also be different. That is, there may be problems with the compatibility of the converted battery with the screwdriver;
• In most cases, 18650 standard banks are used as lithium cells for conversion. They differ in size from Ni─Cd and Ni─MH cans. In addition, you will need a place for the charge-discharge controller and wires. All this will need to fit into a standard screwdriver battery case. Otherwise, it will be extremely inconvenient for them to work;
• A charger for cadmium batteries may not be suitable for charging the battery after it has been rebuilt. It may be necessary to modify the charger or use universal chargers;
• Lithium batteries lose their functionality at low temperatures. This is critical for those who use a screwdriver outdoors;
• The price of lithium batteries is higher than cadmium batteries.

Replacing batteries in a screwdriver with lithium ones

What do you need to consider before starting work?

You need to decide on the number of elements in the battery, which ultimately decides the voltage value. For three elements the ceiling will be 12.6, and for four ─ 16.8 volts. We are talking about converting widely used batteries with a nominal value of 14.4 volts. It is better to choose 4 elements, since during operation the voltage will drop quite quickly to 14.8. A difference of a few volts will not affect the operation of the screwdriver.

In addition, more lithium cells will give greater capacity. This means more operating time for the screwdriver.

Next, you need to choose the right lithium cells themselves. The form factor without options is 18650. The main thing you need to look at is the discharge current and capacity. According to statistics, during normal operation of a screwdriver, the current consumption is in the range of 5-10 amperes. If you press the start button sharply, the current may jump to 25 amperes for a few seconds. That is, you need to choose lithium ones with a maximum discharge current of 20-30 amperes. Then, with a short-term increase in current to these values, the battery will not be damaged.

The nominal voltage of lithium cells is 3.6-3.7 volts, and the capacity in most cases is 2000-3000 mAh. If the battery case allows, you can take not 4, but 8 cells. Connect them two by two into 4 parallel assemblies, and then connect them in series. As a result, you can increase the battery capacity. But not every case will be able to pack 8 cans of 18650.

And the last preparatory stage is the choice of controller. According to its characteristics, it must correspond to the rated voltage and discharge current. That is, if you decide to assemble a 14.4 volt battery, then choose a controller with this voltage. The operating discharge current is usually selected to be two times less than the maximum permissible current.

Above, we established that the maximum permissible short-term discharge current for lithium cells is 25-30 amperes. This means that the charge-discharge controller should be designed for 12-15 amperes. Then the protection will operate when the current increases to 25-30 amperes. Don't forget also about the dimensions of the protection board. It, along with the elements, will need to be placed in the battery case of the screwdriver.

The problem facing everyone who has any kind of electric tool at home that runs on batteries is increasing their service life. Basically, all household models of screwdrivers are equipped with metal hydride (NiMH) or nickel-cadmium (NiCd) batteries. And this is primarily due to their lower price compared to lithium-ion (Li-ion) counterparts.

Despite the high cost, the latter are preferable in many respects. It is enough to indicate only two - the almost complete absence of self-discharge and a longer shelf life. You don’t have to use a screwdriver in everyday life, but only occasionally, so it makes sense to convert the screwdriver battery from NiCd (or NiMH) to a lithium-ion battery yourself, without spending money on an industrial sample. This article is about how to do this.

All voltage values ​​indicated below are only for one of the screwdriver models, as an example of calculations.

Algorithm for converting a battery to a lithium-ion battery

Selection of batteries

It’s worth remembering here high school– when batteries are connected in series, their voltage ratings are summed up. For example, if a screwdriver needs 14.4 V for normal operation, then instead of one (standard) battery it is enough to purchase 4 pieces of 3.3 V each. This is quite enough, since the lithium-ion elements do not “sag” too much when the tool is turned on.

What to consider:

• Once the decision has been made to remake the screwdriver battery, then to achieve the expected effect you should buy mini-batteries from a well-known manufacturer. For example, LiFePO4 batteries from Sistem A123. Their capacity (in mAh) is 2,300, which is quite enough for the normal operation of the electric tool. If you focus on cheap elements “made in China”, then remodeling loses its meaning - these products will not last long.
• Purchasing mini lithium-ion batteries through an online store will allow you to save a lot. They will cost about 900 rubles, while in point of sale for them you will have to pay at least 1,700 - 2,000. The same applies to the charger. This approach will solve the problem at minimal cost, otherwise it’s easier to buy a ready-made Li-ion battery for a screwdriver for 6,800 - 7,150 rubles and not waste time on rework. About, .
• When purchasing batteries, you should pay attention to the presence of copper strips on their terminals. This will greatly facilitate the process of assembling the battery from individual elements (soldering stage).

Selection of tools and materials

The soldering process is distinguished by its specifics. The soldering iron tip heats up to a high temperature, and prolonged thermal exposure is detrimental to the battery. Therefore, it is necessary to keep the heating time to a minimum. This can be achieved if, instead of the traditional flux - pine rosin or alcohol-containing compounds based on it - you use soldering acid. You can purchase it at any point where radio installation tools and parts are sold, or at a car store (spare parts department). The cost of a 20 g soldering bottle is about 35 rubles.

Based on the above, and so that its power is enough to quickly melt the solder. The author used the most common one in everyday life - 65 W/220. It is more difficult to work with a tool of higher power - 100 W - since overheating is difficult to avoid. This requires experience and accuracy. The same applies to a 40 W soldering iron. You will have to increase the heating time, so you can “overdo it”. Although this is a recommendation based personal experience and the author has no right to impose his opinion.

Lithium-ion battery installation

Preparing the “assembly”

Before you start soldering, you should decide on the layout of the battery compartment. That is, arrange all the elements so that they fit comfortably into it. After this, the purchased batteries are secured with adhesive tape (PVC, tape).

Processing of mini-battery contacts

They gradually oxidize. This means they need to be cleaned up a bit. Just lightly, using fine-grained (sanding) sandpaper.

• It begins with degreasing the “contact” part of the battery and briefly heating the applied solder. It is better to tin with easily melting ones, for example, POS-40. The soldering iron should come into contact with the metal of the battery for no more than 1.2 - 2 seconds. Pay special attention when soldering the positive terminal.
• It is advisable to use copper wires as connecting wires, with a cross-section of at least 2.5 square meters. They must be insulated with thermo-cambric.
• All mini-batteries are connected by jumpers according to the diagram. As such, wire or “tires” made of strips of thin metal are used.
• The final step is to connect the wires to the terminals of the battery compartment. If laying the assembly into it is difficult, the stiffening ribs should be removed. They are made of plastic, so using side cutters to get rid of them is easy.

Additionally

It's up to you, the reader, to decide whether to do it or not. But the peculiarity of Li-ion batteries is that they are sensitive to overcharging. Therefore, it is advisable to control the voltage rating not only on the entire assembly, but also on each element separately. This means that in addition to 2 wires “+” and “–”, you need to output 5 more. To limit yourself to just one connector (for both charging and balancing), you can use this one.

Contact wiring diagram

• “+” – 5 and 9.
• “–” – 1 and 6.
• Balancing contacts (ascending) – 2, 7, 3, 8 and 4.

Connectors for connecting to the charger are selected depending on its model. Both connecting cables are soldered according to the diagram.

Despite the fact that the use of lithium-ion batteries provides many advantages - the absence of battery “memory”, extremely low self-discharge, the ability to work as a screwdriver in subzero temperatures, a long shelf life (up to 8 years) - they are more sensitive to compliance with charging technology. If you do not control the voltage rating, then Li-ion batteries are quickly destroyed. Consequently, you will have to purchase a special, more expensive charger. The one that was originally equipped with the screwdriver is not suitable for lithium-ion batteries.

There are recommendations on the Internet for recycling Li- ion batteries, which were previously installed in other technical devices. For example, to ensure autonomous operation of a laptop or telephone (cell phone). There are many options. The author suggests asking a simple question - Is such savings rational if used products do not ensure the normal functioning of the screwdriver, taking into account the specific use of this electric tool? Perhaps it will perform its task for some time, but how effectively and for how long is a completely logical question. Therefore, such advice from various “homemade” people is hardly worthy of attention.

To monitor the condition of the battery cells, you can purchase a voltage indicator. The radio shop will tell you which board is best to use. It is inexpensive - around 180 rubles.

Before reworking the battery, you should look at the screwdriver's data sheet. What is the rated voltage indicated? Depending on this, the required number of elements is selected.

The author draws attention to the fact that without sufficient knowledge of radio engineering, it is not advisable to independently manufacture electronic boards. The slightest mistake, for example, in selecting parts for a balancing circuit will lead to the elements starting to “fly out” one after another, and they will have to be replaced regularly with new mini-batteries.

If you are not sure that the work will be completed efficiently, you should not waste time on remodeling and purchase a lithium-ion battery for the screwdriver in the store. Despite its price, it will ultimately be cheaper than constant resuscitation homemade battery. Or it’s easier to do it - buy the appropriate model of charger. Then you won't have to mount the boards.

In contact with

The cordless tool is more mobile and easier to use compared to its networked counterparts. But we must not forget about the significant drawback of cordless tools; as you yourself understand, the fragility of batteries. Buying new batteries separately is comparable in price to purchasing a new tool. After four years of service, my first screwdriver, or rather the batteries, began to lose capacity. To begin with, I assembled one from two batteries by selecting working “banks,” but this modernization did not last long. I converted my screwdriver to a corded one - it turned out to be very inconvenient. I had to buy the same, but new 12 volt “Interskol DA-12ER”. The batteries in the new screwdriver lasted even less. As a result, two working screwdrivers and more than one working battery. There is a lot written on the Internet about how to solve this problem. It is proposed to remake the ones that have served their purpose Ni-Cd batteries on Li-ion batteries of size 18650. At first glance, there is nothing complicated about this. You remove the old Ni-Cd batteries from the case and install new Li-ion ones. But it turned out that not everything is so simple. The following describes what you should pay attention to when upgrading your cordless tool.

For the remodel you will need:

I'll start with 18650 lithium-ion batteries. Purchased on AliExpress.
The nominal voltage of the elements is 18650 - 3.7 V. According to the seller, the capacity is 2600 mAh, marking ICR18650 26F, dimensions 18 by 65 mm.

The advantages of Li-ion batteries over Ni-Cd are smaller dimensions and weight, with a higher capacity, as well as the absence of the so-called “memory effect”. But lithium ion batteries there are serious disadvantages, namely:

1. Negative temperatures sharply reduce capacity, which cannot be said about nickel-cadmium batteries. Hence the conclusion - if the tool is often used at subzero temperatures, then replacing it with Li-ion will not solve the problem.2. Discharge below 2.9 - 2.5V and overcharge above 4.2V can be critical, and complete failure is possible. Therefore, a BMS board is needed to control charge and discharge; if it is not installed, the new batteries will quickly fail. The Internet mainly describes how to remake a 14-volt screwdriver - it is ideal for modernization. With four 18650 cells connected in series and a nominal voltage of 3.7V. we get 14.8V. - just what you need, even with a full charge plus another 2V, this is not terrible for the electric motor. What about a 12V instrument? There are two options: install 3 or 4 18650 elements, if three then seem to be not enough, especially with partial discharge, and if four - a bit too much. I chose four and in my opinion I made the right choice.

And now about the BMS board, it is also from AliExpress.

The weight of the redesigned battery is 376 grams, therefore, the tool has become 182 grams lighter. In conclusion, I want to say that this alteration is worth it. The screwdriver has become more powerful and the charge lasts much longer than with the original battery. Do it over, you won’t regret it!

In contact with

Rate this homemade product:

59 Added 10 comments To write a comment you must log in to the site via social media. networks (or register): Regular registration

Information

Visitors in the Guests group cannot leave comments on this post.

usamodelkina.ru

Converting a screwdriver battery to Li-Ion

Well, it’s sad to read all these multi-screen discussions (review 1, review 2, review 3, review 4, review 5... etc.), in which it is proposed to buy some kind of charging controllers at a price of just under 2 thousand rubles (for high currents ). It is enough to look at the size of these boards and the size of the powerful field workers on the boards to intuitively understand that something is wrong here.

In one of the discussions, a person was even going to buy an Imax B6. The idea is good, but not because of the battery for the screwdriver. Naturally, everything can be done much simpler and cheaper and without compromising the quality of charging. Next, I skip all the paragraphs about why converting a screwdriver to lithium at all, about the choice of high-current batteries. Actually, I already outlined the text of what I want to say in the discussion on Muska in the next review on this topic. stump August 03, 2016, 10:01 pm A universal recipe for converting screwdrivers, vacuum cleaners and everything else, with any voltage from 12 to... We buy an extension cord with N 220 V sockets, we buy N 0.5 V network adapters (plugs)... 1.0A with USB output, you can buy the very best Chinese ones for 50 rubles (now about 70 rubles). We buy N usb connectors on Ali and there N TP4056 scarf (15 rubles). We get N galvanically isolated “charges” for one Li-ION with an output of 0.5....1.0 A. Next, without any unnecessary equalization boards and extra powerful transistors, we solder a series Li-ION battery and connect all its points (extreme and intermediate) to the connector DB-9 (enough for 4 or 5 consecutive banks, there is a subtlety here, it is better to avoid joint sections of charging wires). Solder the cable: Outputs TP4056 -> DB-9. All!!! Current limitation is determined by the type of battery. Each acc. Always charges fully to 4.2V. You can't get any cheaper. The end of charging - all LEDs on the TP4056 are green (option - blue). You don’t have to buy a network “multiplier”, but simply put the TP4056 adapter strips (N-pairs) into some big old adapter case and put the same DB-9 in the same case.

A screwdriver cannot be recharged in any way, due to the nature of its use (a vacuum cleaner, apparently, can). He just stops pulling. Therefore, no indicators or overdischarge protection are required. Even if you turn on the screwdriver with completely discharged batteries, the voltage on the battery under load will drop to (below) 2 volts. It's OK. When the load is removed (precisely short-term), the voltage on the bank will be restored to 2.5...3.0 volts. It’s impossible not to feel this moment.

And then, just in photographs, I’ll show you how it’s done. I have 4 screwdrivers. Two at the dacha (18V), at home (18V) and at work (12V). If you do it with protection boards/charge controllers, it will be a complete financial ruin, especially considering that 18V screwdrivers require boards for 5 series-connected batteries (they are less common and more expensive). Comments, I think, are practically not required here. Shown is an option for 4 lithium batteries for a 12V screwdriver.

This is my screwdriver. The battery has a DB9F connector.

This is a charger with 4 galvanically isolated channels. At the output, all four channels are “combined” into the DB9M connector.

Naturally, all this can be put into a single box, the output of which will only be a DB9M connector, but having 4 galvanically isolated separate charging channels is very convenient. For example, I converted the power supply of the tester from the Krona to two lithium batteries connected in series from disposable electronic cigarettes. I charge with the same charger, two channels. This design can be repeated by any home craftsman who is far from electronics. A small note/clarification. We connect the batteries in the screwdriver battery housing in series. Four pieces for 12, 14, 16V screwdrivers and 5 pieces for 18V batteries. An 18-volt screwdriver works completely fine even from four Li-Ion batteries, but only on freshly charged batteries. You will have to recharge it much more often. The + and - of the first battery are connected to the DB9.1 and DB9.2 connectors using separate wires that are soldered directly to the battery poles. On DB9.3 it is connected with a separate wire + of the second battery, etc.... According to the electrical diagram, pins 2 and 3 of the DB9 are the same point. However, this is not entirely true from the point of view of the charge board on the TP4056. Shared sections of conductors should be avoided in the charging circuit, because with different currents from two charging boards at a particular time, an error of tens/hundreds of millivolts may appear. It is advisable to install the wires in the charging circuit with a larger diameter (well, in the main discharge circuit, too, naturally). For a screwdriver with an 18V battery, this connection will require 10 contacts. I use the metal housing of the DB9 connector as the 10th contact. Another picture. Option for 18 Volt battery, 5 channels.

How to buy small cheap (40...70 rubles) network adapters on Ali so that they actually produce one ampere is a separate topic. I bought adapters in lots of 5 and 10 pieces. I can’t give a link, because the pages on which the adapters shown in the photographs were purchased, unfortunately, no longer exist. I remember that on the seller’s page there was a picture with load resistors and a USB doctor, on which it was written 0.98 A. I didn’t deceive you, such a current was actually present at the output, although it was accompanied by ripples with a swing of one and a half volts. I had to solder tantalum capacitors inside. One capacitance of 220 μF, 6.3...10V at the output of such adapters is quite enough for the adapter to approach the characteristics of proprietary charging from Apple (pulsations of 50...150 mV are obtained). Instead of a cat.

You can make such a good USB doctor from a voltmeter-ammeter purchased on Aliexpress (100 V, 10 A). It is slightly better than most first-generation “doctors” in terms of voltage drop across the current-measuring shunt. I didn’t measure it exactly, but the figure is about 70 millivolts/1A. This voltage drop is comparable to a "doctor" with OLED display. For the rest (and for the “standard” white “doctor” with a cord), the drop across the shunt is more than 100 mV. Accurate numbers, in fact, are not as easy to obtain as we would like, because each extra USB contact in the circuit “eats” about 30 mV/1.0 A of the flowing current. At high charging currents, old versions of “doctors” included in the circuit can themselves reduce the charging current of a smartphone/tablet, even with short and high-quality USB cords.

Source: stumpof.blogspot.ru

Update from 10/07/2017

When I wrote this note a year ago and duplicated it on the website mysku.ru, they “scold” me there for the “collective farm” implementation of my version of the charger. I'm not too keen on the criticism because I still don't see much point in going through a lot of extra work to make an assistive device that's rarely used. On the other hand, this year I bought a few more memory boards for the TP4056 and found in my “bins” a suitable housing for the network adapter. Well, I made an option, the way it was planned from the very beginning. Maybe someone will like it better this way. It is clear that this is the simplest option for converting a screwdriver to lithium, and this charger is smaller in size than the standard one. Everything is shown in the pictures, and a bit of explanation.

The cheapest white USB network adapters from Ali were used, or rather their internals. The USB connector is sealed off, and a 1500uF*6.3V Low ESR electrolyte is added to the output of each charge (can be found on old motherboards, if the boards are newer, then you can also find tantalum electrolytes 100...200 uF there, this option is even better). Improvement is needed so that you can use the very best Chinese network adapters, regardless of the initial value of their ripples. The fact that these adapters do not always draw a load current of 1A does not affect the performance of the design. Even if the output is only 0.5A, it will work. And there is no need to replace the resistor on the TP4056 1.2 kOhm charger board (charging current 1A) with 2.4 kOhm (charging current 0.5A). It will take a little longer to charge and that’s all. The charger case is some kind of standard transformer network adapter purchased a very, very long time ago at the Chip@Dip store.

Great attention is paid to isolating channels from each other. This is about the photos below. You can’t just get by with a glue gun and stuff a bunch of wires and circuit boards into the case because the mains voltage is high and it all gets quite hot. And we don’t need a short circuit, considering that it’s somehow not customary to monitor the charging process.

A small explanation about the fact that in the main article we were talking about five Li-Ion batteries for screwdrivers with a power supply of 18 V, and in the addition a version for 4 channels is presented. Experience in operating converted batteries has shown that lithium batteries are still more powerful than the original nickel-cadmium batteries. Yes, and there are 5 of them in series (30 ampere), and not 15 pieces. Everything that previously “fell” and “dissipated” at the source now heats the electric motor. As a result, even without a special load, but when turned on for a long time (example: I was drilling a “slippery” stainless steel 5 millimeters thick with a 4...5 mm drill), the motor begins to smell of burnt insulation. Therefore, to avoid this, I removed all the “fifth” batteries from three 18-volt screwdrivers. Result:

It’s not very visible, but two red LEDs and two blue ones are lit here (they are white because the plexiglass is yellow). Once all the red lights go out, you can start working with Shurik. “Equalization” occurs “automatically” at 4.2 volts.

I forgot to write, but this is important. If anyone is interested, please note that the adapter body from Chip@Dip initially has ventilation slots, and I myself drilled additional holes on the bottom and sides. In a closed case, this entire structure can “give up” due to overheating.

mysku.ru

3S-4S BMS boards or one of the options for converting a screwdriver for lithium

Board dimensions:

The dimensions of the boards are very small, only 56mm*21mm for the blue one and 50mm*22mm for the red one:

Appearance:

Let's start with the blue protection board:

Unfortunately, according to the seller, the operating current is only 8A, but judging by the datasheets, one AO4407A mosfet is designed for 12A (peak 60A), and we have two of them:

I will also note that the balancing current is very small (about 40ma) and balancing is activated as soon as all cells/banks switch to CV mode (second charge phase). Connection:

The red board is simpler, because it does not have a balancer:
It is also based on the protection controller – S8254AA, but is designed for a higher operating current of 15A (again, according to the manufacturer):

Looking at the datasheets for the power mosfets used, the operating current is stated to be 70A, and the peak current is 200A, even one mosfette is enough, but we have two of them:

The connection is similar:

So, as we can see, both boards have a protection controller with the necessary isolation, power mosfets and shunts to control the passing current, but the blue one also has a built-in balancer. I haven't looked into the circuit too much, but it looks like the power mosfets are paralleled, so the operating currents can be multiplied by two. Important note - maximum operating currents are limited by the current shunts! These scarves do not know about the charging algorithm (CC/CV). To confirm that these are precisely protection boards, one can judge by the datasheet for the S8254AA controller, in which there is not a word about the charging module:

The controller itself is designed for a 4S connection, so with some modification (judging by the datasheet) - soldering the connector and resistor, perhaps the red scarf will work:

It’s not so easy to upgrade the blue scarf to 4S; you’ll have to solder on the balancer elements.

Board testing:

So, let's move on to the most important thing, namely how suitable they are for real use. The following devices will help us for testing:

A prefabricated module (three three/four register voltmeters and a holder for three 18650 batteries), which appeared in my review of the iCharger 208B charger, however, without a balancing tail:

Step-down DC/DC converter with current limiting and lithium charging capability:

Charger and balancing device iCharger 208B for discharging the entire assembly The stand is simple - the converter board supplies a fixed constant voltage of 12.6V and limits the charging current. Using voltmeters, we look at what voltage the boards operate at and how the banks are balanced. First, let's look at the main feature of the blue board, namely balancing. There are 3 cans in the photo, charged at 4.15V/4.18V/4.08V. As we can see, there is an imbalance. We apply voltage, the charging current gradually drops (lower gauge):

Since the scarf does not have any indicators, the completion of balancing can only be assessed by eye. The ammeter was already showing zeros more than an hour before the end. For those interested, here is a short video about how the balancer works in this board:

As a result, the banks are balanced at 4.210V/4.212V/4.206V, which is quite good:

When applying a voltage slightly higher than 12.6V, as I understand it, the balancer is inactive and as soon as the voltage on one of the cans reaches 4.25V, the S8254AA protection controller turns off the charge:

The situation is the same with the red board, the S8254AA protection controller also turns off the charge at the level of 4.25V: Now let’s go through the load cutoff. I will discharge, as I mentioned above, with an iCharger 208B charger and balancing device in 3S mode with a current of 0.5A (for more accurate measurements). Since I don’t really want to wait for the entire battery to drain, I took one dead battery (green Samson INR18650-25R in the photo). The blue board turns off the load as soon as the voltage on one of the cans reaches 2.7V. In the photo (without load -> before shutdown -> end): As you can see, the board turns off the load at exactly 2.7V (the seller stated 2.8V). It seems to me that this is a little high, especially considering the fact that in the same screwdrivers the loads are huge, therefore, the voltage drop is large. Still, it is advisable to have a cutoff of 2.4-2.5V in such devices. The red board, on the contrary, turns off the load as soon as the voltage on one of the cans reaches 2.5V. In the photo (without load -> before shutdown -> end): Here everything is generally fine, but there is no balancer.

Update 1: Load test:

The following stand will help us in terms of recoil current: - the same holder/holder for three 18650 batteries - 4-register voltmeter (total voltage control) - car lamps incandescent as a load (unfortunately, I only have 4 incandescent lamps of 65W each, I don’t have any more) - HoldPeak HP-890CN multimeter for measuring currents (max 20A) - high-quality copper stranded speaker wires large cross-section A few words about the stand: the batteries are connected by a “shaft”, i.e. as if one after another, to reduce the length of the connecting wires, and therefore the voltage drop across them under load will be minimal:

Connecting cans on a holder (“jack”):

The probes for the multimeter were high-quality wires with crocodile clips from the iCharger 208B charger and balancing device, because HoldPeak’s do not inspire confidence, and unnecessary connections will introduce additional distortions. First, let's test the red protection board, as it is the most interesting in terms of current load. Solder the power and can wires:

It turns out something like this (the load connections turned out to be of minimal length):

I already mentioned in the section on remaking Shurik that such holders are not really designed for such currents, but they will do for tests. So, a stand based on a red scarf (according to measurements, no more than 15A):

Let me briefly explain: the board holds 15A, but I don’t have a suitable load to fit into this current, since the fourth lamp adds about 4.5-5A more, and this is already beyond the limits of the board. At 12.6A, the power mosfets are warm, but not hot, just right for long-term operation. At currents of more than 15A, the board goes into protection. I measured with resistors, they added a couple of amperes, but the stand was already disassembled. A huge plus of the red board is that there is no protection blocking. Those. When the protection is triggered, it does not need to be activated by applying voltage to the output contacts. Here's a short video:

Let me explain a little. Since cold incandescent lamps have low resistance, and are also connected in parallel, the board thinks that a short circuit has occurred and the protection is triggered. But due to the fact that the board does not have a lock, you can warm up the coils a little, making a “softer” start. The blue scarf holds more current, but at currents of more than 10A, the power mosfets get very hot. At 15A the scarf will last no more than a minute, because after 10-15 seconds the finger no longer holds the temperature. Fortunately, they cool down quickly, so they are quite suitable for short-term loads. Everything would be fine, but when the protection is triggered, the board is blocked and to unlock it, you need to apply voltage to the output contacts. This option is clearly not for a screwdriver. In total, the current is 16A, but the mosfets get very hot:

Conclusion: my personal opinion is that a regular protection board without a balancer (red) is perfect for a power tool. It has high operating currents, an optimal cut-off voltage of 2.5V, and is easily upgraded to a 4S configuration (14.4V/16.8V). I think this is the best choice for converting a budget Shurik for lithium. Now for the blue scarf. One of the advantages is the presence of balancing, but the operating currents are still small, 12A (24A) is somewhat not enough for a Shurik with a torque of 15-25Nm, especially when the cartridge almost stops when tightening the screw. And the cutoff voltage is only 2.7V, which means that under heavy load, part of the battery capacity will remain unclaimed, since at high currents the voltage drop on the banks is significant, and they are designed for 2.5V. And the biggest disadvantage is that the board is blocked when the protection is triggered, so use in a screwdriver is undesirable. It is better to use a blue scarf in some homemade projects, but again, this is my personal opinion.

Possible application schemes or how to convert Shurik’s power supply to lithium:

So, how can you change the power supply of your favorite Shurik from NiCd to Li-Ion/Li-Pol? This topic is already quite hackneyed and solutions, in principle, have been found, but I will briefly repeat myself. To begin with, I’ll just say one thing - in budget shuriks there is only a protection board against overcharge/overdischarge/short circuit/high load current (analogous to the red board under review). There is no balancing there. Moreover, even some branded power tools do not have balancing. The same applies to all tools that proudly say “Charge in 30 minutes.” Yes, they charge in half an hour, but the shutdown occurs as soon as the voltage on one of the banks reaches the nominal value or the protection board is triggered. It is not difficult to guess that the banks will not be fully charged, but the difference is only 5-10%, so it is not so important. The main thing to remember is that a balanced charge lasts for at least several hours. So the question arises, do you need it?

So, the most common option looks like this:

Network charger with a stabilized 12.6V output and current limitation (1-2A) -> protection board -> 3 batteries connected in series The result: cheap, fast, acceptable, reliable. Balancing depends on the state of the cans (capacity and internal resistance). This is a completely working option, but after a while the imbalance will make itself felt in the operating time.

More correct option:

Network charger with stabilized output 12.6V, current limitation (1-2A) -> protection board with balancing -> 3 batteries connected in series The result: expensive, fast/slow, high quality, reliable. Balancing is normal, battery capacity is maximum. So, we will try to do something similar to the second option, here’s how you can do it: 1) Li-Ion/Li-Pol batteries, protection boards and a specialized charging and balancing device (iCharger, iMax). Additionally, you will have to remove the balancing connector. There are only two disadvantages - model chargers are not cheap, and they are not very convenient to service. Pros - high charging current, high balancing current of the cans 2) Li-Ion/Li-Pol batteries, protection board with balancing, DC converter with current limiting, power supply 3) Li-Ion/Li-Pol batteries, protection board without balancing (red) , DC converter with current limiting, power supply. The only downside is that over time the cans will become unbalanced. To minimize imbalance, before remaking the shurik, it is necessary to adjust the voltage to the same level and it is advisable to take cans from the same batch. The first option will only work for those who have a model memory, but it seems to me that if they needed it, then they have already remade their shurik a long time ago. The second and third options are practically the same and have the right to life. You just need to choose what is more important – speed or capacity. I believe that the last option is the best option, but only once every few months you need to balance the banks.

So, enough chatter, let's get to the remodeling. Since I don’t have experience with NiCd batteries, I’m talking about the conversion only in words. We will need:

1) Power supply:

First option. Power supply (PSU) at least 14V or more. The output current is desirable to be at least 1A (ideally about 2-3A). We will use a power supply from laptops/netbooks, from chargers (output more than 14V), units for powering LED strips, video recording equipment (DIY PSU), for example this or this one:

If the option without a balancer is used, then it is necessary to solder the balancing connector. This is necessary to control the voltage on the banks, i.e. to assess imbalance. And as you understand, you will need to periodically recharge the battery one by one with a simple TP4056 charging module if imbalance begins. Those. Once every few months, we take the TP4056 scarf and charge one by one all the banks that, at the end of the charge, have a voltage below 4.18V. This module correctly cuts off the charge on fixed voltage 4.2V. This procedure will take an hour and a half, but the banks will be more or less balanced. It’s written a little chaotically, but for those in the tank: After a couple of months, we put the screwdriver’s battery on charge. At the end of the charge, we take out the balancing tail and measure the voltage on the banks. If you get something like this - 4.20V/4.18V/4.19V, then balancing is basically not needed. But if the picture is as follows - 4.20V/4.06V/4.14V, then we take the TP4056 module and charge two banks in turn to 4.2V. I don’t see any other option other than specialized chargers-balancers. 3) High current batteries:

I have previously written a couple of small reviews about some of them - tyts and tyts. Here are the main models of high-current 18650 Li-Ion batteries: - Sanyo UR18650W2 1500mah (20A max.) - Sanyo UR18650RX 2000mah (20A max.) - Sanyo UR18650NSX 2500mah (20A max.) - Samsung INR18650-15L 1500mah (18A max.) - Samsung INR18650-20R 2000mah (22A max.) - Samsung INR18650-25R 2500mah (20A max.) - Samsung INR18650-30Q 3000mah (15A max.) - LG INR18650HB6 1500mah (30A max.) - LG INR18650HD2 2 000mah (25A max.) - LG INR18650HD2C 2100mah (20A max.) - LG INR18650HE2 2500mah (20A max.) - LG INR18650HE4 2500mah (20A max.) - LG INR18650HG2 3000mah (20A max.) - SONY US18650VTC3 16 00mah (30A max.) - SONY US18650VTC4 2100mah (30A max.) - SONY US18650VTC5 2600mah (30A max.) I recommend the time-tested cheap Samsung INR18650-25R 2500mah (20A max.), Samsung INR18650-30Q 3000mah (15A max.) or LG INR18650HG2 3000mah (20A max.). I haven’t had much experience with other jars, but my personal choice is Samsung INR18650-30Q 3000mah. The Skis had a small technological defect and fakes with low current output began to appear. I can post an article on how to distinguish a fake from an original, but a little later, you need to look for it.

How to put all this together:

Thus, the wires connecting the batteries will be short, therefore, the drop in precious voltage in them under load will be minimal. I do not recommend using holders for 3-4 batteries; they are not intended for such currents. Side-by-side and balancing conductors are not so important and can be of smaller cross-section. Ideally, it is better to stuff the batteries and the protection board into the battery compartment, and the step-down DC converter separately into the docking station. LED indicators charge/charged can be replaced with your own and displayed on the docking station body. If you wish, you can add a minivoltmeter to the battery module, but this is extra money, because the total voltage on the battery will only indirectly indicate the residual capacity. But if you want, why not. Here it is:
Now let's estimate the prices: 1) PSU - from 5 to 7 dollars 2) DC/DC converter - from 2 to 4 dollars 3) Protection boards - from 5 to 6 dollars 4) Batteries - from 9 to 12 dollars (3-4 $ thing) Total, on average, $15-20 for a rework (with discounts/coupons), or $25 without them.

Update 2, a few more ways to remake Shurik:

The following option (suggested from the comments, thanks to I_R_O and cartmannn):

Use inexpensive 2S-3S chargers like SkyRC e3 (this is the manufacturer of the same iMax B6) or all kinds of copies of B3/B3 AC/imax RC B3 (tys) or (tys) The original SkyRC e3 has a charging current for each bank of 1.2A versus 0 ,8And for copies, it must be accurate and reliable, but twice as expensive as copies. You can buy it very inexpensively on the same Banggood. As I understand from the description, it has 3 independent charging modules, something akin to 3 TP4056 modules. Those. SkyRC e3 and its copies do not have balancing as such, but simply charge the banks to one voltage value (4.2V) at the same time, since they do not have power connectors. The SkyRC assortment actually includes charging and balancing devices, for example, SkyRC e4, but the balancing current is only 200mA and costs around 15-20 dollars, but it can charge life cards (LiFeP04) and charge currents up to 3A. Those who are interested can familiarize themselves with the SkyRC model range. Total for this option You need any of the above 2S-3S chargers, a red or similar (without balancing) protection board and high-current batteries:

As for me, it’s a very good and economical option, I’d probably stick with it.

Another option proposed by comrade Volosaty:

Use the so-called “Czech balancer”:

It’s better to ask him where it’s sold, it’s the first time I’ve heard about it :-). I can’t tell you anything about currents, but judging by the description, it needs a power source, so the option is not so budget-friendly, but seems interesting in terms of charging current. Here is a link to the article. In total, for this option you need: a power supply, a red or similar (without balancing) protection board, a “Czech balancer” and high-current batteries.

Advantages:

I have already mentioned the advantages of lithium power supplies (Li-Ion/Li-Pol) over nickel ones (NiCd). In our case, a head-to-head comparison – a typical Shurik battery made of NiCd batteries versus lithium: + high energy density. A typical 12S 14.4V 1300mah nickel battery has a stored energy of 14.4*1.3=18.72Wh, and a 4S 18650 14.4V 3000mah lithium battery has 14.4*3=43.2Wh + no memory effect, i.e. e. you can charge them at any time, without waiting for complete discharge + smaller dimensions and weight with the same parameters as NiCd + fast charging time (not afraid of high charge currents) and clear indication + low self-discharge The only disadvantages of Li-Ion can be noted: - low frost resistance batteries (they are afraid of negative temperatures) - balancing of the cans when charging and the presence of overdischarge protection is required. As we can see, the advantages of lithium are obvious, so it often makes sense to rework the power supply...

Conclusion: the scarves under review are not bad and should be suitable for any task. If I had a shurik on NiCd cans, I would choose a red scarf for conversion, :-)…

The product was provided for writing a review by the store. The review was published in accordance with clause 18 of the Site Rules.