Powerful li ion balancer. DIY balancer for li-ion batteries

Peculiarities:

-Balance

-

-Current control

-

Description of pins:

Peculiarities:

-Balance: HCX-D119 control board for 3S/4S Li-Ion batteries has a built-in balancer function. At the same time, during the charging process of the battery, the voltage on each of the cells is equalized to a value of 4.2V.
In order to use the voltage equalization function, you need to keep the battery at a voltage of 12.6/16.8 V for at least 60 - 120 minutes after the end of the active phase of charging the battery. For the balancer to operate, it is important that the voltage is no higher than 12.6 / 16.8V: if these voltages are exceeded, the controller will enter a protection state and the batteries will not be balanced

-Voltage control on each cell: When the voltage on any of the cells exceeds the threshold values, the entire battery is automatically turned off.

-Current control: When the load current exceeds the threshold values, the entire battery is automatically switched off.

- Can work with 3S batteries(3 series batteries) HCX-D119 controller is 100% compatible with Li-Ion batteries 3S (11.1V). To switch the controller to 3S mode, you need to jumper the contacts R8, and move the resistor R7 to R11 (R7, however, remains open) and connect the “B1” pad to the “B-” pad

Description of pins:

Assessing the characteristics of a particular charger is difficult without understanding how an exemplary charger should actually operate. charge li-ion battery 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.

Most common sizes li-ion batteries are shown in the table below (they all 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 a constant charging current of a 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 voltage idle move circuits will never be able to 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 correct charger operation is its complete disconnection from the battery after charging is complete. 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 ensured DC reduced value 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 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 for 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 trimming 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 one 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 PCB option with smd led and micro USB connector:

LTC4054 (STC4054)

Very simple circuit, 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 the 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).

A transistor will do just fine any p-n-p, 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 hardest thing here is to find the source reference voltage TL431. 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 maximum value 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).

Most main drawback Such charging requires constant monitoring of 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 valid values for this 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 he cannot do automatically is make decisions about fully charged 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 point 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 passivation layer that covers the lithium anode. This layer prevents a chemical reaction between the anode and the 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.

Science does not stand still, as a result of which lithium-polymer batteries have become firmly established in our daily lives. The 18650 elements alone are worth it - only the lazy don’t know about them. And in a hobby radio controlled models There has been a qualitative leap to a new level! Compactness, high current output and low weight provide wide scope for improving existing battery-based power systems.

Science has gone even further, but for now we will focus on the Li Ion version (lithium-ion).
So, the store purchased a charger and balancing device from the Turnigy brand for charging 2S and 3S assemblies lithium polymer batteries(a type of lithium ion, hereinafter referred to as LiPo).






My Cessna 150 radio-controlled foam plane (a model made of foam ceiling tiles) is equipped with a 2S battery - the number in front of the S indicates the number of LiPo cells connected in series. Charging was the same as before, but carrying a charger in the field could be easier and cheaper.

Why so much trouble?
When charging lithium polymer batteries, several rules must be followed: the current must be maintained at 0.5C...1C, and the battery voltage should not exceed 4.1...4.2 V.
If the assembly contains several elements connected in series, then small deviations in one of them will eventually lead to premature damage to the batteries if the circuit is not balanced. This effect is not observed in NiCd batteries or NiMh.
As a rule, all elements in an assembly have close, but not the same, capacity. If two elements with different containers are connected in series, then the element with a smaller capacity charges faster than the one with a larger one. Since the charging process continues until the cell with the largest capacity is charged, the battery with the smaller capacity will be overcharged. During discharge, on the contrary, elements with lower capacity are discharged faster. This leads to the fact that after many charge-discharge cycles, the difference in capacities increases, and due to frequent recharging, the elements with the most low capacity quickly become unusable.
This problem can easily be eliminated if you control the potential of the elements and ensure that all elements in the block have exactly the same voltage.
Therefore, it is highly advisable to use not just a charger, but one with a balancing function.

Equipment: charger + power cable with crocodile clips for connecting to a 12-15 Volt power supply or 12 Volt battery.
The charger consumes no more than 900 mA when charging.
Two indicators green and red - green power control, red lights up when the charging-balancing process is in progress. At the end of the process or when the balancing connector is removed, the red LED goes out.
Charging occurs up to a voltage of 4.2 V per cell. Voltages were measured at work using a standard voltmeter. The voltage at the end of the charge on the 1st and 2nd elements was equal to 4.20 Volts, on the 3rd element there was a slight overcharge of 4.24 Volts.

Dismemberment:


The circuit is partly classic: a step-up converter, then 3 comparators giving a signal to the controller (worn out markings in the Chinese style). But the power part of the circuit caused confusion. The reason for getting into the guts was my carelessness. I accidentally cut off the balancing wires on the 3S battery (from a screwdriver) and when soldering, I mixed up the outputs of elements 1 and 3, as a result, when connected to the charger (charger), smoke came out of the latter. A visual inspection revealed a faulty transistor N010X for which I did not find a description, but I found a reference to an analogue - it turned out to be a P channel field-effect transistor




The remaining parts were found to be in good condition upon inspection. There were no stocks of P channel field grass at home; the prices at the local store were crazy. This is where the ancient Zuksel dialup modem came in handy, which contained the part I needed (with more best characteristics). Since my eyesight and the size of the part did not allow me to install everything in place, I had to be perverted and install the part in the free space on the back side.
What I didn’t like about the power part was that in 2S mode the charger works like most similar ones, but with the 3rd element it’s not so simple. The part burned out for a reason; it performed the function of supplying voltage to the battery being charged as a whole. Functionally, all three elements are charged at once; as elements 1 and 2 are charged, the transistors open and the elements are shunted through resistors, thereby allowing the current to bypass the charged elements. Field-effect transistor cuts off the voltage as a whole, it also controls the charge of the 3rd element. And if the 3rd element is charged before the 1st and 2nd, then power goes through the diode to charge the remaining elements. In general scheme muddy, I come to the conclusion that it is an elementary saving of parts.

The culprit of the adventures that befell me:


A Bosch screwdriver converted to lithium batteries from a laptop to replace NiCd batteries that died from crystallization. At the moment, the charger has become a standard charger for the converted screwdriver. A full charge cycle (4Ah) occurs in about 6 hours, but I have never discharged the battery to zero, so there is no need for a long charge.

Conclusion
Budget charger. In a particular case it came in handy. The screwdriver is happy.
The charging current of 800mA limits the minimum capacity of the charged elements. Carefully look at the description of your battery, where the maximum charge current is indicated. Violation of operating instructions can lead to damage and fire of batteries.

I'm planning to buy +21 Add to favorites I liked the review +22 +46

For charging LiPo batteries large capacity, inexpensive charging balancers are not entirely suitable due to the limited charging current, as a result of which the charge of high-capacity batteries (2...5 A) is extended over a very long time. The proposed charger is designed for charging 2S....3S LiPo batteries of high capacity with their balancing and individual shutdown of the banks, on which the voltage has reached 4.2 Volts.

This circuit is designed for charging 2S and 3S batteries, but if necessary
To charge 4S or 5S batteries, just increase the number of cells. All cells are the same.

Let's look at the principle of operation of the memory using the example of one cell. The basis is precision
Zener diode TL431 with adjustable switching threshold. The switching threshold is set resistively
voltage divider at the terminal of the zener diode control electrode.
Until the zener diode turns on, all the charging current flows through the battery. Zener diode via
resistor 1 Kom is connected in parallel to the battery, and the voltage on the positive bus, as well as on the resistive divider (and on the control electrode of the zener diode) gradually increases as the battery is charged. When the battery voltage reaches 4.2 Volts
The zener diode opens and the voltage drop across the 1 Kohm resistor opens the power
transistor KT816. The charging current now passes through it. The warning light comes on
Light-emitting diode. A chain of 4 series-connected powerful diodes and an FE transistor junction
are a powerful zener diode with a stabilization voltage of about 4.2 Volts, which
prevents the battery from discharging through the open junction of the transistor.
Resistor *22 Kom should be selected in such a way that when it reaches the corresponding
battery bank with a voltage of +4.2 Volts, the zener diode opened and the signal light came on
Light-emitting diode.

Transformer TN36 or similar.
Transistors KT816 (collector current 3 A).
Diodes - powerful KD226 diodes with a current of at least 2 A.
Powerful wire variable resistor 10…..20 Ohm to adjust the charge current.
Ammeter 1….3 A, to control the charge current.

Each transistor has a small radiator 20 x 40 mm made of 1 mm aluminum.

The output voltage supplied from the rectifier to the balancer must exceed
voltage of the battery being charged. Used in rectifier diode bridge for current 3 A
and a capacitor of 2200 microfarads x 36 Volts.

For one can, the voltage from the rectifier should be about 6 Volts.
For two cans, the voltage from the rectifier should be about 11 Volts.
For three cans, the voltage from the rectifier should be about 15 Volts.
For four cans, the voltage from the rectifier should be about 20 Volts.

If necessary, you can switch the transformer windings.
The cut-off voltage of a charged can is 4.2 volts.

The charging current for batteries is set by a powerful wirewound variable resistor 10...20 Ohms within 1...2 A, and for small capacity batteries within 0.5 A.
I've been using this charger for two years. I charge 1.8……….3.0 A batteries.

Schematic diagram charging - LiPo balancer.

File.lay

Installation

Negative of the printed circuit board for three charging cells (3S LiPo). View from the paths.

Option for the design of the charger. Front view. The diodes are lit - the charge is complete.

Back view. The axis of the variable wirewound resistor for setting the current is visible.

General view of the interior.

General view of the interior

View of the printed circuit board.

Visible are a variable resistor, a diode bridge, and a filter capacitor.

Especially for skeptics and adherents of microcontrollers, I want to say the following.
I in no way deny the advantages of microcontrollers over 80s technologies!
But the circuit design and technologies of the 80s are accessible even to beginning radio amateurs, which cannot be said about microprocessors. In this article, I just want to show my colleagues that using simple Soviet radio elements, you can assemble something in a couple of days without much effort and material costs.
or any other device needed for business!
I would also like to especially note that when our engineers did not yet have calculators, but calculated on slide rules, all their grandiose projects worked! Enough to remember
The Venera spacecraft of the 70s, which landed on the surface of Venus and transmitted color photographs to Earth. And Soviet lunar rovers and the world's best aircraft of the 50s! And of course, the flight of Yuri Gagarin! In those years, all calculations were made on slide rules! Of course, I have a calculator and more than one. But I also know how to use a slide rule.

I welcome everyone who stopped by. The review will focus, as you probably already guessed, on two simple headsets designed to monitor Li-Ion battery assemblies, called BMS. The review will include testing, as well as several options for converting a screwdriver for lithium based on these boards or similar ones. For anyone interested, you are welcome under cat.
Update 1, Added a test of the operating current of the boards and a short video on the red board
Update 2, Since the topic has aroused little interest, I will try to supplement the review with several more ways to remake Shurik to make a kind of simple FAQ

General form:


Brief performance characteristics of the boards:


Note:

I want to warn you right away - only the blue board has a balancer, the red one does not have a balancer, i.e. This is purely an overcharge/overdischarge/short circuit/high load current protection board. And also, contrary to some beliefs, none of them have a charge controller (CC/CV), so for their operation a special board with a fixed voltage and current limitation is required.

Board dimensions:

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




Here is a comparison with AA and 18650 batteries:


Appearance:

Let's start with:


Upon closer inspection, you can see the protection controller – S8254AA and balancing components for the 3S assembly:


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:


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 charger, although without a balancing tail:


- two-register ampere-voltmeter for current monitoring (lower readings of the device):


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


- charging 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 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 (no 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 (no load->before shutdown->end):


Here everything is generally fine, but there is no balancer.

Update 1: Load test:
The following stand will help us with the output current:
- the same holder/holder for three 18650 batteries
- 4-register voltmeter (control of total voltage)
- 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 section

A few words about the stand: the batteries are connected by a “jack”, 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 most optimal 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 stabilized output 12.6V and current limitation (1-2A) -> protection board ->
The bottom line: 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
In summary: expensive, fast/slow, high quality, reliable. Balancing is normal, battery capacity is maximum

So, we’ll 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 can balancing current
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 altering 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 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 power supply), for example, or:


- Step-down DC/DC converter with current limiting and the ability to charge lithium, for example or:


- Second option. Ready-made power supplies for Shuriks with current limiting and 12.6V output. They are not cheap, as an example from my review of the MNT screwdriver -:


- Third option. :


2) Protection board with or without balancer. It is advisable to take the current with a reserve:


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 charge the screwdriver battery. 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 short reviews about some of them - and. 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 2000mah (25A max.)
- LG INR18650HD2C 2100mah (20A max.)
- LG INR18650HE2 2500mah (20A max.)
- LG INR18650HE4 2500mah (20A max.)
- LG INR18650HG2 3000mah (20A max.)
- SONY US18650VTC3 1600mah (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:


Well, a few words about the connection. We use high-quality copper stranded wires with a decent cross-section. These are high-quality acoustic or ordinary SHVVP/PVS with a cross-section of 0.5 or 0.75 mm2 from a hardware store (we rip the insulation and get high-quality wires of different colors). The length of the connecting conductors should be kept to a minimum. Batteries preferably from the same batch. Before connecting them, it is advisable to charge them to the same voltage so that there is no imbalance for as long as possible. Soldering batteries is not difficult. The main thing is to have a powerful soldering iron (60-80W) and an active flux (soldering acid, for example). Solders with a bang. The main thing is to then wipe the soldering area with alcohol or acetone. The batteries themselves are placed in the battery compartment from old NiCd cans. It is better to arrange it in a triangle, minus to plus, or as popularly called “jack”, by analogy with this (one battery will be located in reverse), or there is a good explanation a little higher (in the testing section):


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. The charge/charged LED indicators 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 :

Now let's estimate the prices:
1) BP – 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 per item)

Total, on average, $15-20 for a remodel (with discounts/coupons), or $25 without them.

Update 2, a few more ways to remake Shurik:

The next option (suggested from the comments, thanks I_R_O And cartmann):
Use inexpensive 2S-3S type chargers (this is the manufacturer of the same iMax B6) or all kinds of copies of B3/B3 AC/imax RC B3 () or ()
The original SkyRC e3 has a charging current per cell of 1.2A versus 0.8A for copies, should be accurate and reliable, but twice as expensive as copies. You can buy it very inexpensively at the same place. 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. SkyRC's assortment actually includes charging and balancing devices, for example, but the balancing current is only 200mA and costs around $15-20, but it can charge life-changing devices (LiFeP04) and charge currents up to 3A. Anyone interested can check out 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 suggested 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 the link to. 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, while a 4S 18650 14.4V 3000mah lithium battery has a stored energy of 14.4*3=43.2Wh
+ no memory effect, i.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 are:
- low frost resistance of batteries (they are afraid of negative temperatures)
- balancing of the cans during charging and the presence of overdischarge protection is required
As you can see, the advantages of lithium are obvious, so it often makes sense to rework the power supply...
+173 +366