Characteristics of a car battery - what should you pay attention to? Car battery Battery maximum discharge current.

Let's take a look behind the scenes of the company and ask a few questions to the engineer of the company supplying Russian market some of the best AGM and GEL batteries.

– Hello, Mikhail, please tell us about the manufacturing technology and features of Delta batteries

Hello, Sergey! Most series of DELTA batteries are manufactured using AGM technology (Absorber Glass Mat - editor's note). This technology allows you to get rid of the use of electrolyte in a liquid state. AGM technology batteries use a separator (lead plate separator - editor's note) made of fiberglass material with an absorption coefficient of 10-11 to 1 by weight, and impregnated with electrolyte.

The electrodes are arranged alternately, interspersed with an absorber-separator, and tightly compressed into an element battery. Pressing prevents the plates from falling off. All this gives the AGM battery resistance to vibration, allows you to significantly increase the service life of the batteries and, if desired, operate the battery not only in a vertical position (upside down is not recommended - editor's note). Now there is no need to add water to the electrolyte to achieve the required concentration; AGM batteries are maintenance-free. The released gases - hydrogen, oxygen - recombine inside the housing and do not leave the battery.

– What about gel batteries?

In the series (GX, GSC series - editor's note), a composite gel is used as an electrolyte, which ensures the battery's resistance to deep discharges and high temperature stability.

– What is the maximum charging current that can be used for batteries of the DTM, HR, HRL, GX series without harming the battery life?

For lead-acid batteries made using AGM technology ( DTM, HR, HRL), the current limit when charging with constant voltage is 30% of the rated capacity with a ten-hour discharge, i.e. 0.3 C10 [A]. For lead-acid batteries using GEL technology, given value is 0.2 C10 [A]. For example, for a Delta HRL 12-100 battery, the nominal capacity with a ten-hour discharge is 100 Ah, and the maximum charging current should not exceed 0.3 × 100 Ah = 30 A. For Delta batteries of all series, these parameters are given in the documentation.

– How do the HR and HRL series fundamentally differ from each other from a consumer point of view?

The main fundamental difference, from the consumer’s point of view, between battery series is the battery life. For HR series batteries, the design service life is 5 years in buffer mode, and for HRL series batteries, this parameter is at the level of 10-12 years.

For the 3 older models of the HR series, the service life is also 10 years. The main differences are that technologically, HRL uses additional agents (special chemical components added to the active mass of the electrodes - editor's note) to increase resistance to adverse factors and reduce the rate of corrosion and degradation of elements when exposed to these factors. Those. Under ideal conditions, the three senior HR models will last as long or nearly as long as the HRL. But when stress factors appear: non-compliance with operating temperature conditions, exceeding the permissible charge current, deep discharge, storage in a discharged state, etc. , the difference will become obvious and will be reflected in the rate of aging and, as a result, in the life of the battery.

Plus, the HRL series has increased energy efficiency at short discharges.

– Is there any advantage to the HR series over the DTM for discharges longer than 2 hours?

The DTM series is universal and is used in both low-current systems and uninterruptible power supply systems. The HR series belongs to the DELTA UPS Series line, designed specifically for use in uninterruptible power supplies. The following aspect is fundamental: moving from series to series “up the steps” from junior to senior (DTM-> DTM-L>HR->HR-W->HRL->HRL-W), a number of changes occur in the technological component, i.e. .e. additional additives, agents and other expensive modifiers are used that can increase not only discharge characteristics in certain ranges, but also affect resistance to corrosion in particular and degradation of elements in general.

– Please tell us more about degradation processes.

Fine! Such processes include:

• Corrosion of the positive electrode grid is a reaction with the formation of lead sulfate due to direct contact of the positive active mass with the grid material. With the right combination of alloy composition, acid concentration and operating temperature, the rate of destruction can be significantly reduced. When the positive electrode grid is corroded, the transient electrical resistance at the interface of the grid with the active mass increases, reducing the battery capacity.
• Degradation of the active mass of the positive electrode is caused by electrical and chemical processes when the battery operates in cyclic mode. Leads to loosening of the active mass, loss of contact of particles with the main mass and their exclusion from participation in the main charge/discharge reaction.
• Sulfation is the process of formation of lead sulfate at the cathode and anode. For a number of reasons, such as: deep discharge, chronic undercharging - low charge voltage, storage without recharging, high temperatures not subject to recovery when charging.
• Drying is the loss of water from the electrolytic solution. Loss of water in sealed systems occurs when excess pressure is released due to the accelerated formation of hydrogen and oxygen if the battery operating rules are not followed.
• TO possible consequences aging of the battery also includes shedding of the active mass of the plates and short circuit.

– The HRL-W series battery has watts in its name, why not AC? How to correctly calculate the capacity of such batteries?

The name of the battery models of the HRL-W series (batteries with increased energy efficiency) indicates the discharge power [W/Cell] at a 10-minute discharge to increase efficiency when calculating the battery life of the consumer in uninterruptible power supply systems. Having this indicator in the name, you can carry out an estimation calculation without referring to bit tables and quickly select a model. At the same time, it is very convenient that the capacities of DELTA batteries of this series are indicated in the battery labeling, in contrast to a number of manufacturers who use this technique without indicating the capacity.

It is technologically possible to achieve an increase in energy efficiency [W/Cell] with short discharges, while simultaneously reducing the amount of lead, reducing cost, but at the same time reducing the battery life and its capacity with a ten-hour discharge. Unscrupulous manufacturers of AGM batteries may use this technique.

The capacity of such batteries should be specified in the data sheet for the battery.

– What extremely low residual voltage on AGM and GEL batteries should be set in the inverter settings for correct and long-term operation of the battery in the event of rare discharges.

Recommended value ultimate voltage the end of the discharge (residual voltage) depends on the discharge current: The lower the current, the greater the value of the consumer shutdown voltage. For example, with a discharge of 0.2C or less, it is not advisable to regularly discharge the battery below 1.8VEl. And during discharges with high currents of 1C-nom or more, it is permissible to decrease to a consumer cut-off voltage value of 1.6-1.65 V/cell.

Discharge characteristics

For example, when discharging a battery with a current of more than 100 A, it is not recommended to discharge it to more than a level of 9.6 V, and with discharge currents less than 20 A, the recommended level of residual voltage is 10.8 V

– Some manufacturers claim that their AGM batteries can operate at temperatures down to -60 degrees. How would you comment on this?

At an ambient temperature of -60C°, lead-acid batteries cannot be fully operational without heating. This is due to a decrease in the efficiency of chemical processes. It must be remembered: the greater the discharge current when operating at subzero temperatures, the more significant the loss of capacity. Those. The loss of capacity during discharge with a current of 1C and 0.1C can differ by 5-6 times. It is much more difficult to charge the battery at this temperature. For example, even at -30C°, high-capacity OPzV batteries consume virtually no charging current.

Because charging at low temperatures without preheating the battery is extremely difficult, and sometimes impossible, and there is a risk of electrolyte freezing. For example, in a charged state, the density of the electrolyte is 1.26 – 1.3 g/cm³, at this density the freezing temperature is -60°C, and with a completely discharged battery, the concentration will be 1.18 – 1.22 g/cm3 and the freezing temperature is from minus 22 to minus 40°C.

When freezing, the electrolyte increases in volume (the density in the solid state is lower) and, as a result, damage to the plates and even the housing occurs. Batteries with thinner electrodes, the number of which will be greater than those of AGM stationary batteries (for example, starter batteries), will feel better at negative temperatures. This is due to the larger total surface area of ​​the electrodes, i.e. a large volume of active mass that enters into the reaction. But thin plates cannot provide corrosion resistance, because... Because their thickness is smaller, they degrade faster. And as a result, you have to choose: better discharge characteristics or longer service life.

Brief summary in simple words:

• Firstly, during discharge, the concentration of the electrolyte decreases, which increases its freezing temperature, which can lead to damage to the battery case (the possibility of discharge without freezing the electrolyte by 10-15%).
• Secondly, if the battery is not strongly discharged, to a state where the electrolyte has not yet frozen, then it is no longer possible to charge it, due to the multiple slowdown in the course of chemical reactions. This means that at an operating temperature of minus 60°C the battery becomes disposable.

– When working with UPS or inverters, is it necessary to perform training cycles? If so, how often and to what depth should batteries be discharged?

The control and training cycle (CTC) is an operation that allows, first of all, to determine the residual capacity of the batteries. CTC is required to obtain a more accurate understanding of the condition of the batteries and timely replacement. CTC is carried out by fully charging the battery, followed by discharging it with a fixed current equal to 10% of the rated capacity. The discharge time is recorded. The residual voltage after a ten-hour discharge is indicated in the documentation and is usually 1.8 V/El. The remaining battery capacity is determined by the discharge time.

Before operating lead-acid batteries, it is recommended to perform an equalizing charge. An equalizing charge is used when there is a voltage variation across batteries (cells or monoblocks) - more than +/-1%. Scatter can occur both between batteries in the same circuit and between elements of the same battery under conditions of deep discharge or chronic undercharging. An undercharged battery connected in series with other batteries will discharge faster, will not release the declared energy and will be subject to degradation processes associated with too deep a discharge. Accordingly, when charging the battery circuit, the “overdischarged” battery will not restore its charge to 100% and over time will begin to adversely affect the condition of the batteries of the entire circuit, which will also be subjected to too deep a discharge. To avoid this situation, it is necessary to carry out an equalizing charge of the battery circuit before putting the system into operation.

The equalizing charge is carried out with an increased constant voltage (Not higher than 14.4 V) for no more than 48 hours until the charge current remains unchanged for 2 hours. If the maximum battery temperature of 50 °C is exceeded, the charge should be suspended for a couple of hours to cool the battery.

Mikhail Frolov, Delta battery engineer, answered our questions

Currently, lead-acid batteries are the most common. There are a huge number of manufacturers of such batteries on the market. Each manufacturer strives to improve the parameters of its products and puts a lot of effort into this. But, if the recommended parameters and operating conditions are not observed, even the most unpretentious and reliable models of lead-acid batteries can be damaged. Correct operation can significantly extend the life of even inexpensive batteries (such as the Delta DT series). Although AGM batteries are maintenance-free, they are still worth paying attention to.

– Thanks for the detailed answers, Mikhail!

Please! If you have any questions, please contact us!

A car battery is a very important element, despite the simplicity of its design, it is fraught with several incomprehensible abbreviations, such as capacity, and of course starting current. I have already written about some, I will write about some more, but today we will talk about the “starting indicators” of the battery - why this is so important and what they should be. Not everyone knows about this parameter and often when choosing a new battery, they initially make a big mistake! And it leads to the fact that the battery quickly fails and cannot start your car in winter...

To begin with, the definition

Battery starting current (sometimes called starter current) - this is the maximum value of the current required to start the engine, namely to power the starter so that it can turn the flywheel with the pistons attached to it. This process is complex, because the pistons compress the fuel (9–13 atmospheres), which enters the chambers. Winter starting is even more difficult, because the oil thickens and the starter needs to overcome not only compression, but also the lack of normal lubrication of the cylinders.

What is the main purpose of a car battery? Of course, the accumulation and subsequent start of the engine, it seems like the structure of many models is the same, but the characteristics are not the same. No, of course, the charged model will have approximately 12.7V, but the current strength and capacity will differ.

A few words about the structure and properties

Batteries were created specifically to recharge and start the car, that is, they are very practical from the point of view of operation. A regular battery discharged very quickly, and it was expensive to change it; that’s when batteries were invented.

Through trial and error, batteries evolved - so a few years after the invention, a very specific model emerged, this was about 100 years ago, which has not changed until now.

Usually these are six compartments with plates made of lead (negative) and its oxide (positive), which are filled with a special electrolyte made of sulfuric acid. It is this combination that makes the battery work; if one component is excluded, the operation will be disrupted. One scattered battery generates an average of 2.1V, this is extremely little to start the engine; in an average battery, they are combined by connecting them in series, usually 6 banks of 2.1V = 12.6 - 12.7V. This voltage is enough to excite the starter winding.

A few words about capacity

However, voltage is only one of the components; it is unified, that is, it is the same for all batteries, regardless of capacity.

But the capacity can differ significantly. It is measured in Amperes per hour, or simply Ah. If we derive a small definition, then this is the ability of a battery to deliver a certain amount of current for an entire hour. Automotive options start at 40 Ah and go up to 150 Ah. However, the most common ones on ordinary foreign cars are 55 – 60 Ah. That is, the battery can deliver 60 Amps for an hour, and then it will be completely discharged. To be honest, this is a big value, if you multiply 12.7 (voltage) and 60 Ah (capacity), you get 762 Watts per hour! You can warm up the electric kettle a couple of times.

We also sorted out the capacitance, now let’s talk directly about the starting current.

So what is this inrush current?

As I already wrote above, the starting current is the maximum current that the battery can deliver in a very short period of time. In simple words To start the engine of an average car you need approximately 255 - 270 Amps, a lot! In essence, these are “starting values”, from the word “start” in relation to the power unit.

If the battery capacity is approximately 60 Ah, then this exceeds its nominal value by approximately 4 - 5 times. True, such tension should only be given for about 30 seconds, no more.

Often in the southern regions of our country, where the air temperature always remains in the positive zone, this parameter is not even considered! Because no matter what, we take an average battery, and it will cope with its duties perfectly. After all, it’s warm outside and the oil is liquid. But in the northern regions this indicator is one of the most important, where temperatures are often in the extremely negative zone and start power unit complicated, the oil looks more like jelly than a flowing liquid. The launch will be extremely difficult.

If to start the engine at “+ 1 + 5” degrees, 200 - 220 Amperes will be enough (at one time), then to start it already at - 10 - 15 degrees, you need to spend 30% more energy, and this is 260 - 270 Amps. Now think about how much energy is wasted at -20 - 30 degrees Celsius.

Thus, the lower the temperature in winter, the more important this parameter is, this is a kind of axiom.

What does the starting current depend on?

If you look at different manufacturers, for example European countries, the USA, Russia or China, then all these batteries will have a different inrush current. So, for example, if you compare 55 Ah China and Europe, the difference can be 30 - 40%! But why is that?

It's all about technology:

• The use of purified lead, even in simple acid batteries, will lead to rapid charging and subsequent discharging, and accordingly the starting values ​​will increase.
• A larger number of plates in a body of the same dimensions.
• More electrolyte.
• The plus plates are more porous, which will allow more charge to accumulate.
• Hermetic designs do not allow the electrolyte to evaporate, which will allow the battery to always maintain the desired level without exposing the plates.

Of course, you can add build quality and integrity of the manufacturer, all this gives better results than competitors. It’s true that such batteries are more expensive.

But at the moment, there are also new technologies - the record holders for the return of starting current are, their return current can reach up to 1000 Amperes in 30 seconds, about 3 - 4 times more than that of conventional acid options. Although these technologies also have their disadvantages, and first of all this is the price.

It is also worth noting that when starting the engine, the battery voltage drops to approximately 9 Volts, but the current increases many times - this is a normal process. After starting the engine, the voltage will return to its normal level of 12.7 Volts, and the spent charge will be replenished by the car’s generator. If the voltage readings during startup drop to 6 Volts (and take a very long time to recover), then this can be critical; the starter simply does not have enough energy to start. Most likely the battery is failing.

How are measurements taken?

After the battery is produced, it must be tested to determine the starter voltage. Testing in production facilities is complex; batteries are often placed in negative temperatures, cool them for several hours, then try to start the engine.

Usually the tests take place at -18 degrees Celsius and the start-up lasts 30 seconds; if the battery copes, then it can be put into production. If not, change the design, filling, and carry out tests on a new one.

They measure several times, that is, there are a number of intervals with maximum values, at such intervals the maximum currents that this particular instance is capable of producing are measured, they are recorded and later applied to the “sides” of the battery. It should be noted that not all batteries in the batch are tested so strictly. However, “defects” are present, checks are taking place load fork.

In fairness, it is worth noting that earlier in Soviet times, batteries were not filled with electrolyte at all in production (there was a concept of a dry charge), you yourself had to fill and charge them! That is, we buy an electrolyte of the required density, and then charge it for 12 – 24 hours.

What is the starting current of an average battery and what should I do if I buy a larger value?

At the moment there is a division of starting values ​​into gasoline and diesel units. After all, a diesel engine initially needs a higher indicator, because its compression ratio is much higher, can reach up to 20 atmospheres.

SO, the averages:

For gasoline options this is 255 Amperes

For diesel options - at least 300 Amperes

These figures, as they say, were measured at minus 18 degrees Celsius, which may not be enough when starting in severe frosts.

But now, with the development of technology, we can often see starter current indicators in stores of 400, 500 and even 600 Amperes! What happens if you take these numbers? Am I burning my starter?

The answer is simple - of course not. Don't burn it! Take it and forget what a cold start is, with such characteristics you won’t care about any frost.

As for the starter - with a higher current, it will rotate faster and stronger, which will allow it to more revolutions, and in turn this contributes to quick and high-quality engine starting.

Of course, you need to read the characteristics of your car, but I think a starting value of 450 - 500 AMPERES will be enough for all regions of Russia. Again, I’ll make a reservation, I’m now considering ordinary cars, not trucks, with large and high-volume engines; often even 600 will not be enough for them.

Classification in the world

As I have already touched on a little, in the world there are now several main classifications of inrush current values. Which have their own identification and labeling methods. To begin with, how are they marked:

• German manufacturers stand out here - they apply the “DIN” marking
• In America they apply “SAE”
• In European Union countries (not Germany) they apply “EN”
• In Russia they often write “starting or starting current”

From operating experience

NiMH cells are widely advertised as high-energy, cold-resistant and memoryless. Having bought a Canon PowerShot A 610 digital camera, I naturally equipped it with a capacious memory for 500 pictures highest quality, and to increase the duration of filming I bought 4 NiMH cells with a capacity of 2500 mAh from Duracell.

Let's compare the characteristics of industrially produced elements:

Table 1.

From the table we see NiMH elements have a high energy capacity, which makes them preferable when choosing.

To charge them, a DESAY Full-Power Harger smart charger was purchased, which provides charging of NiMH cells with their training. The elements were charged efficiently, but... However, on the sixth charge, it died for a long time. Electronics burned out.

After replacement charger and several charge-discharge cycles, the batteries began to run out in the second or third ten shots.

It turned out that despite the assurances, NiMH cells also have memory.

And most modern portable devices that use them have built-in protection that turns off the power when a certain minimum voltage. This prevents the battery from being completely discharged. This is where the memory of elements begins to play its role. Cells that are not fully discharged receive an incomplete charge and their capacity decreases with each recharge.

High-quality chargers allow you to charge without losing capacity. But I couldn’t find something like this on sale for elements with a capacity of 2500mAh. All that remains is to periodically train them.

NiMH cell training

Everything written below does not apply to battery cells with strong self-discharge . They can only be thrown away; experience shows that they cannot be trained.

Training NiMH cells consists of several (1-3) discharge-charge cycles.

Discharge is performed until the voltage on the battery cell drops to 1V. It is advisable to discharge the elements individually. The reason is that the ability to accept charge may vary. And it intensifies when charging without training. Therefore, the voltage protection of your device (player, camera, ...) is triggered prematurely and the undischarged element is subsequently charged. The result of this is an increasing loss of capacity.

Discharge must be performed in a special device (Fig. 3), which allows it to be performed individually for each element. If there is no voltage control, then the discharge was carried out until the brightness of the light bulb noticeably decreased.

And if you time the light bulb burning time, you can determine the battery capacity, it is calculated by the formula:

Capacity = Discharge current x Discharge time = I x t (A * hour)

A battery with a capacity of 2500 mAh is capable of delivering a current of 0.75 A to the load for 3.3 hours, if the time obtained as a result of discharging is less, and accordingly the residual capacity is less. And when the required capacity decreases, you need to continue training the battery.

Now, to discharge battery cells, I use a device made according to the circuit shown in Fig. 3.

It is made from an old charger and looks like this:

Only now there are 4 light bulbs, as in Fig. 3. We need to say something about light bulbs separately. If the light bulb has a discharge current equal to the rated current for a given battery or slightly less, it can be used as a load and an indicator, otherwise the light bulb is only an indicator. Then the resistor must be of such a value that the total resistance of El 1-4 and the resistor R 1-4 parallel to it is about 1.6 Ohms. Replacing a light bulb with an LED is unacceptable.

An example of a light bulb that can be used as a load is a 2.4 V krypton flashlight light bulb.

A special case.

Attention! Manufacturers do not guarantee normal work batteries at charging currents exceeding the accelerated charging current I charge must be less than the battery capacity. So for batteries with a capacity of 2500mAh it should be below 2.5A.

It happens that NiMH cells after discharge have a voltage of less than 1.1 V. In this case, it is necessary to apply the technique described in the above article in the PC WORLD magazine. An element or a series group of elements is connected to a power source through a 21 W car light bulb.

Once again I draw your attention! Such elements must be checked for self-discharge! In most cases, it is the elements with reduced voltage that have increased self-discharge. These items are easier to throw away.

It is preferable to charge individually for each element.

For two elements with a voltage of 1.2 V, the charging voltage should not exceed 5-6V. During forced charging, the light bulb also serves as an indicator. When the brightness of the light bulb decreases, you can check the voltage on the NiMH element. It will be greater than 1.1 V. Typically, this initial, forced charging takes from 1 to 10 minutes.

If the NiMH element does not increase the voltage during forced charging for several minutes and gets hot, this is a reason to remove it from charging and discard it.

I recommend using chargers only with the ability to train (regenerate) the cells when recharging. If there are none, then after 5-6 operating cycles in the equipment, without waiting for a complete loss of capacity, train them and reject elements with strong self-discharge.

And they won't let you down.

One of the forums commented on this article "it's written stupidly, but there's nothing else". So this is not “stupid”, but simple and accessible for anyone who needs help to do in the kitchen. That is, as simple as possible. Advanced people can install a controller, connect a computer, ......, but that’s another story story.

So that it doesn't seem stupid

There are "smart" chargers for NiMH cells.

This charger works with each battery separately.

He can:

1. work individually with each battery in different modes,
2. charge batteries in fast and slow mode,
3. individual LCD display for each battery compartment,
4. charge each battery independently,
5. charge from one to four batteries different capacities and standard size (AA or AAA),
6. protect the battery from overheating,
7. protect each battery from overcharging,
8. determination of the end of charging by voltage drop,
9. identify faulty batteries,
10. pre-discharge the battery to residual voltage,
11. restore old batteries (charge-discharge training),
12. check battery capacity,
13. display on the LCD display: - charge current, voltage, reflect the current capacity.

The most important thing, I EMPHASIZE, this type of device allows you to work individually with each battery.

According to user reviews, such a charger allows you to restore the majority of neglected batteries, and serviceable ones can be used for the entire guaranteed service life.

Unfortunately, I have not used such a charger, since it is simply impossible to buy it in the provinces, but you can find a lot of reviews in the forums.

The main thing is not to charge at high currents, despite the stated mode with currents of 0.7 - 1A, this is still a small-sized device and can dissipate power of 2-5 W.

Conclusion

Any restoration of NiMh batteries is strictly individual (with each individual element) work. With constant monitoring and rejection of elements that do not accept charging.

And it is best to restore them with the help of intelligent chargers that allow you to individually perform rejection and a charge-discharge cycle with each element. And since there are no such devices that automatically work with batteries of any capacity, they are designed for elements of a strictly defined capacity or must have controlled charging and discharging currents!

The rechargeable battery is the most important component of backup and autonomous power supply systems for individual electrical appliances or entire industrial and domestic facilities. Today, lead-acid batteries (AGM VRLA and GEL VRLA), OPZS, OPZV, as well as nickel-cadmium (Ni-Cd) and lithium-ion types (Li-ion, LiFePO4, Li-pol) are widely used.

The emergence of chemical power sources began back in 1800, when the famous Italian scientist Alessandro Volta placed plates of copper and zinc in acid and obtained a continuous voltage (Volta column). Modern lead-acid batteries, as the name suggests, consist of lead and acid, where the positively charged element is lead and the negatively charged element is lead oxide. The most common rechargeable battery consists of six 2V cells and has a total voltage of 12V.

Battery Specifications

The quality of batteries can be determined by several important properties:

Capacity, Ampere/hour;

Voltage, Volt;

Permissible discharge depth, %;

Service life, years;

Operating temperature range, °C;

Self-discharge, %;

Dimensions, mm;

• Charge current, A;

Advice! i> Be sure to take into account that all battery characteristics given by the manufacturer are indicated for a temperature of 20 - 25 ° C; with a decrease or increase in the ambient temperature where the battery will be used, the performance indicators change, as a rule, they decrease.

Battery capacity

This parameter reflects the amount of energy that the battery can store, measured in Ampere hours. Currently in Ukraine you can buy batteries with capacities from 0.6 to 4000 Ah. For example, a battery with a capacity of 200Ah is capable of powering a load with a current of 2A for 100 hours, or a current of 8A for 25 hours, etc. Be sure to take into account that with an increase in current consumption, the capacity of the battery will decrease, which is why manufacturers indicate the capacity with an additional parameter - C.

An additional, but very important characteristic is marked with the Latin letter “C” with a numerical parameter, usually from 1 to 48 hours and indicates the capacity of the battery when discharged in a certain period of time (C1, C5, C10, C20, etc.) . The C10 value is considered to be the standard value and the vast majority of manufacturers indicate the capacity at a 10-hour discharge. For example, a capacity of 100Ah at C10 means that the battery will provide this capacity with a 10-hour discharge, the same battery at C5 will have a lower capacity - 80Ah at C5, and if the discharge occurs over 20 hours, the capacity will increase and amount to about 115Ah at C20. Thus, when choosing the battery capacity, it is necessary to take into account the time during which the discharge will be carried out, this is of great importance.

Figure No. 1.

Advice! Please note that some manufacturers and distributors may indicate the capacitance value at C20. This is done to artificially inflate the indicator while keeping the cost of the battery unchanged.

During operation, the capacity will gradually decrease; this is a natural process of “aging” of the battery, which occurs due to a decrease in the density of the lead plates and partial loss of primary lead from the positive and negative plates. High intensity of use and deep discharges will lead to rapid wear of the positive and negative plates of the battery and its failure. To prevent this from happening, it is necessary to provide a reserve supply of capacity. To increase the capacity of the battery cabinet, several batteries with parallel connection are used.

Battery voltage

Voltage level is a key characteristic based on which a battery is selected. Today, cells and batteries with the following voltage values ​​are common: 1.2, 2.4, 6, 12V. Battery bank with more high voltage(24, 48, 96V, etc.) is assembled using several 12V batteries with a serial connection type.

By measuring the voltage level, you can assess the state of charge and the degree of wear of maintenance-free types of batteries (AGM and GEL VRLA). The voltage measurement is carried out over several hours when the battery is completely idle and disconnected from the charger. The normal level for AGM batteries is considered to be from 13 to 13.2V.

Allowable discharge depth

Different types and subtypes of batteries have recommended discharge depth parameters. Below is table No. 1, which shows the most common characteristics of batteries with permissible and recommended depth of discharge.

Table No. 1. Values ​​of permissible and recommended battery discharge values.

The level of discharge is a key factor in the service life of the battery, along with the intensity of use. Even the most expensive and high-quality lead-acid battery can be destroyed in 7-10 days if a full 100% discharge to a voltage of 9V is performed several times in a row.

The most resistant to deep discharges are lithium-ion and nickel-cadmium, as well as specialized lead acid batteries, which have been optimized by the developers for deep discharges. Typically, such series contain the word “Deep” in the title, which means “Deep”.

Battery life

Modern lead-acid batteries are optimized for a variety of operating conditions. Some have a shorter service life, but provide a higher discharge characteristic, others have a longer service life, but are suitable for rare discharges and operation in buffer mode, etc. Therefore, if the manufacturer indicates a service life of 10 years, this information corresponds to the ideal operating mode, when not the cyclic life and, more importantly, the depth of discharge are exceeded. Let's give an example: if the manufacturer indicated that the battery life is 10 years and the number of charge/discharge cycles allowed is 600 with a depth of 50%. The battery can serve the specified period under ideal operating conditions and no more than five cycles per month. This mode fully corresponds to the buffer type.

The service life depends entirely on the number of charge and discharge cycles completed, and also depends on the environment where the battery is installed. As noted above, the more the battery is discharged and the longer it is in a discharged state, the less it will last. The higher ambient temperature, the more active the chemical reaction takes place and the more susceptible the lead plates are to destruction.

Table No. 2 shows approximate values ​​for the service life and cyclic resource of batteries depending on their types. The data corresponds to an optimal operating temperature of 20 – 25°C.

Table No. 2. Resource depending on the type of battery.

Figure No. 2.

Operating temperature range

With the exception of the lithium-ion type, which uses the mineral lithium, the operating principle of batteries is based on chemical elements and the interaction between them. Therefore, almost all the main characteristics of batteries depend on the ambient temperature. As a rule, as the temperature increases, the service life decreases, and if the temperature is above ~35 ° C, the service life of lead-acid AGM batteries will be halved.

The ambient temperature level also affects the available battery capacity. As the temperature drops, the capacity drops. At –20°C, the battery capacity will decrease by 30–40% of the nominal value.

Figure No. 3.

Figure No. 4.

Battery self-discharge

Self-discharge is a characteristic phenomenon for batteries of all types. This indicator reflects the degree of spontaneous loss of capacity during idle time after a full charge. The self-discharge characteristic is indicated as a percentage over a certain period of time, most often per month.

As an example, consider a 100Ah AGM VRLA battery that has been fully charged and not used for a month. The average self-discharge value for AGM VRLA type is about 1.5%, respectively, after a month the capacity will be about 98.5 Ah.

Self-discharge rates are influenced by ambient temperature. As the temperature rises, the indicator will increase. The cause of self-discharge is the release of oxygen molecules on the electrode of a positive charge, and an increase in temperature is a catalyst for this process.

Figure No. 5.

Charge current

The current used to charge the battery directly depends on the capacity of the battery being charged. Lead-acid batteries are charged with a current of 10–30% of the rated capacity; depending on the system, less powerful chargers can be used.

Attention! You cannot charge batteries with high current, this leads to irreversible chemical reactions significantly reduces performance characteristics batteries.

Figure No. 6.

Dimensions and weight of batteries

Depending on the capacity of the batteries, the dimensions and weight vary, with rare exceptions there may be changes in size for the same capacity. There are generally accepted sizes of small batteries up to 250Ah, which are used as built-in power supplies for uninterruptible power supply systems, children's toys, golf carts, scrubber dryers, etc. Depending on the manufacturer, the connecting dimensions may differ from tenths to several millimeters.

Advice! Pay attention to the height of the battery without terminals and with terminals; some manufacturers indicate two heights.

Battery discharge is the most important mode of battery operation, in which consumers are provided with current. The process of battery discharge is described by an electrochemical reaction:

Lead sulfate and water are formed, so as the battery discharges, the density of the electrolyte decreases.

The nature of the discharge depends on many characteristics describing the condition of the battery and external factors. The entire variety of battery discharge modes is described by a relatively small set of discharge characteristics.

Battery discharge characteristics

The main discharge characteristics are the following values ​​that change during the discharge time at a constant normal discharge current:

• - resting emf - emf that changes linearly during the discharge process from 2.11 V to 1.95 V;
• - electrolyte density - varies from 1.28 to 1.11 g/cm3;
• - battery voltage: initial is 2.11 V, final discharge voltage is 1.7 V;
• - discharge current;
• - discharge capacity of the battery.

The first three characteristics do not require further explanation. Let's focus on the last two.

Discharge capacity is the amount of electricity released by the battery when discharged.

However, the battery capacity depends on the discharge conditions. Therefore, the very concept of capacity is associated with discharge conditions. This concept of capacity is a comparative characteristic.

The discharge capacity of a battery is the amount of electricity supplied by the battery when discharged by normal current.

The normal discharge current is the 10-hour discharge current.

Along with this, the value of the discharge current of the 20-hour discharge mode is used. Most manufacturers indicate the battery capacity in a 20-hour discharge mode.

On the graphs of voltage versus time during discharge with a constant current, a decreasing almost straight line is observed, and at the end of the discharge the voltage decreases linearly and quickly. The battery should not be discharged below 1.7 V.

The degree of battery discharge can be characterized by relative residual capacity.

Relative residual capacity is defined as the amount of electricity that a battery is capable of delivering at normal discharge current, starting at a given point in time, divided by the capacity of the same serviceable and fully charged battery.

Qrest. rel. fairly fully characterizes the energy state of the battery at the moment of operation.

For example, if the battery is not worn out, it has largest capacity and fully charged, then Qrest. = Qmax.

and therefore the battery has a residual relative capacity of 100%.

However, for example, if the battery is heavily sulfated, it charges up to 2.7 V with intense gas evolution (fully charged) and is able to discharge at normal discharge current.

Of course, the relative discharge capacity of a battery depends on many factors that determine the condition of the battery at the current time of operation. This is basically:

• - battery charge level;
• - electrolyte density;
• - electrolyte temperature;
• - charge mode.

A strict and correct correspondence between these charging and discharging characteristics is necessary. Therefore Qrest. rel. - an important diagnostic characteristic. Knowing it, you can avoid supercritical, emergency operating modes of the battery.

For example, if Qrest. rel. = 75%, and the electrolyte temperature is 25 C, then the starter operating mode of the battery is already supercritical, i.e. The density of the electrolyte must be strictly determined at a given temperature and state of charge of the battery. The battery must be fully charged without overcharging or undercharging.

Select the discharge mode in accordance with the condition of the battery (this condition is often violated, especially in the cold season, when using the starter for a long time in an attempt to start a particularly faulty engine). If you neglect this, you can defrost the battery or some of its (most discharged) batteries.

Thus, knowing the main discharge characteristics of the battery, their interdependence and impact on the residual capacity of the battery, you can protect the battery from premature wear and failure.

Let us recall once again the main negative discharge factors that sharply reduce battery life:

• - deep discharge;
• - constant undercharging mode;
• - non-compliance with the standard electrolyte density;
• - sulfation of the plates;
• - excessive (supercritical) discharge currents.

The discharge capacity of the battery is influenced by the density of the electrolyte. However, the concentration of sulfuric acid in starter batteries is not determined by considerations of obtaining maximum capacity, but is associated with other factors: service life, self-discharge current, performance at low temperatures.

Therefore, you should adhere to the basic rules: the battery must be fully charged (preferably with reverse current), and the electrolyte concentration must correspond to the established norm.

The discharge capacity of a battery strongly depends on the discharge current and electrolyte temperature. In most cases, manufacturers indicate the battery capacity for a 20-hour discharge mode at T = 25 C. That is, discharge current, for example, of a battery with a capacity of Q=60A. h is equal to

Iр = 60/20 = 3A

However, the same battery has a discharge capacity at a current of 200A (starter discharge mode) of no more than 20 Ah. That is, In this mode, the battery discharges lower acceptable values during

Tr = 20/200 = 0.1 hour = 6 minutes

As the temperature drops, the discharge capacity of the battery also decreases greatly. This largely depends on the design of the battery, however, most batteries, for example, at - 10 C have a capacity 2 times less than at +25 C. This explains the difficulty in cranking the crankshaft with the starter in winter conditions (in addition to the increased mechanical load due to thickening lubricants).

Discharge characteristics make it possible to determine the condition of the battery and prevent its operation beyond the permissible characteristics.

The modes of deep (lower than practical at U=1.7V) discharge and systematic undercharging are especially unacceptable. In this case, the starter discharge currents quickly destroy the plates. The degree of discharge of the battery can be determined by the density of the electrolyte.

When checking a battery with a load fork, you can determine the degree of discharge of each battery depending on the voltage.