Consider the labeling of LiPo batteries using the example of a battery that has the following inscriptions:
- 3000 - capacity in mAh (mAh);
- 11.1V- nominal voltage;
- 3S- the number and order of connection of cans (individual batteries from which the battery is assembled) - this means that the battery is connected in series from 3 batteries, that is, the battery capacity will be 3000mAh, and the voltage will be 3.7x3 = 11.1V;
- 20C- discharge current (on a 3000 mAh battery means that the maximum continuous discharge current is 20 * 3000 = 60,000 mA = 60A).
Voltage
On batteries, instead of voltage, the number of cans is written.
The voltage of one can is 3.7 V. Accordingly, 3 cans are equal to 11.1 V.
The number of cans is indicated by the letter S.
Discharge current
Denoted by a letter C and the number of capacitance factors.
For example, if the battery says 20C, and its capacity is 3000 mAh (3 Ah),then the recoil current is 3 Ah * 20 C = 60 A
Peak discharge current
The current that the battery can deliver for a short period of time (which is also indicated in the characteristics). This is usually 10-30 seconds.
It is indicated in the same way as the discharge current, by the second number.
20C-30C means that the discharge current is 20C, and the peak current is 30C.Capacity
It is indicated in mAh (milliampere-hour). 1000 mA / h = 1 A / h.
Battery charging.
LiPo batteries are charged with a current of 1C (unless otherwise indicated on the battery itself, recently they have appeared with the ability to charge with a current of 2 and 5C). The nominal charging current of the battery is 1000 mAh - Ampere. For a 2200 battery, there will be 2.2 amperes, and so on.
The computerized charger balances the battery (equalizes the voltage on each battery bank) during charging. Although it is possible to charge 2S batteries without connecting the balancing cable, we highly recommend always connect the balancing connector! Charge 3S and large assemblies only with the balance wire connected! If you do not connect and one of the cans picks up more than 4.4 volts, then an unforgettable fireworks display awaits you!
The battery charges up to 4.2 volts per cell (typically a few millivolts less).
Storage mode.
On a computerized charger, you can put the LiPo into storage mode, while the battery will be charged / discharged up to 3.85V per cell. Fully charged batteries will die when stored for more than 2 months (maybe less). They say that they are completely discharged too, but for a longer period.
Exploitation.
It is not recommended to discharge the LiPo battery lower than 3 volts per cell - it may die. Engine governors have a function to shut off the engine when this condition occurs. We use s or. We also recommend using. It is connected to the balancing connector and when it beeps, it's time to land.
When the motor consumes more current than the battery can give, LiPo tends to swell and die. So this must be monitored strictly!
Now there are nano-tech batteries with a current output of 25-50C.
Preparation for work.
Getting the LiPo ready for use is easy - just charge it and that's it! :)
This type of battery does not have a memory effect (no need to re-discharge before recharging), no need to cycle - do charge-discharge cycles before use.
If you are charging in the field, then you should look for batteries with accelerated charging, they write Fast charge 2C or 5C. In theory, they can be charged with a current of 33 Amperes!
The charger has a maximum of 5A, but this will also reduce charging from 50 minutes to 20! (battery 1000 mAh)
A car battery is a very important element, despite the simplicity of its design, it conceals 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 it 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 complicated, because the pistons squeeze the fuel (at 9 - 13 atmospheres), which enters the chambers. Winter start-up is even more difficult, because the oil thickens and the starter needs to overcome not only compression, but also the lack of normal cylinder lubrication.
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. Of course, the charged model will have about 12.7V, but the current strength and capacity will differ.
A few words about the structure and properties
The batteries were created precisely in order to recharge and start the car, that is, they are very practical from the point of view of operation. An ordinary battery was discharged very quickly, and it was expensive to change it, then batteries were invented.
By trial and error, batteries evolved - so a few years after the invention, a very specific model emerged, it was about 100 years ago, which has not changed until now.
Usually these are six compartments with plates of lead (minus) and its oxide (plus), which are filled with a special electrolyte of sulfuric acid. It is this combination that makes the battery work, if you exclude one component, then the work will be disrupted. One scattered battery, generates an average of 2.1V, this is extremely small for starting the engine, in an average battery, they are connected in series, usually 6 cells of 2.1V = 12.6 - 12.7V. This voltage is sufficient to energize the starter winding.
A few words about capacity
However, the 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. Measured in Amperes per hour, or simply Ah. If you deduce a small definition, then this is the ability of the battery to give a certain current strength for an entire hour. Car options start at 40 Ah and go up to 150 Ah. However, the most common on ordinary foreign cars - 55 - 60 Ah. That is - the battery can give 60 Amperes for an hour, and then it will be discharged. To be honest, this is a large value, if you multiply 12.7 (voltage) and 60 Ah (capacity), you get 762 watts per hour! You can heat up the electric kettle a couple of three times.
We also figured out the capacity, now directly about the starting current.
So what is the starting current?
As I wrote above, the starting current is the maximum current that the battery can give in a very short period of time. In simple words, to start the engine of an average car, you need about 255 - 270 Amperes, a lot! In fact, these are the "starting values", from the word "start" in relation to the power unit.
If the capacity of the battery is approximately 60 Ah, then this exceeds its rating by about 4 - 5 times. True, such a voltage should be given only 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! For no reason, we take an average battery, and it will perfectly cope with its duties. After all, it's warm outside and the oil is liquid. But in the northern regions this indicator is one of the most important, there temperatures are often in an extremely negative zone and it is difficult to start the power unit, the oil looks more like jelly than a fluid liquid. The launch will be extremely difficult.
If to start the engine at "+ 1 + 5" degrees, it will be enough (at once) 200 - 220 Amperes, then to start already at - 10 - 15 degrees, you need to spend 30% more energy, which is 260 - 270 Amperes. Now think about how much energy is spent 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, the countries of Europe, the USA, Russia or China, then all these batteries will have a different starting current. So, for example, if you compare 55 Ah China and Europe, the difference can be 30 - 40%! But why is it so?
It's all about technology:
- The use of purified lead, even in simple acid batteries, will lead to quick charging and subsequent discharge, and the starting values will increase accordingly.
- More plates in the same size case.
- More electrolyte.
- Plus plates are more porous, which will allow more charge to accumulate.
- Sealed structures, do not allow electrolyte to evaporate, which will allow the battery to always keep the desired level without exposing the plates.
Of course, you can add both the build quality and the decency of the manufacturer, all this gives better results than those of competitors. True, such batteries are more expensive.
But at the moment, there are also new technologies - they are the record holders for the return of the starting current, their return current can reach up to 1000 Amperes in 30 seconds, about 3-4 times more than that of conventional acid versions. Although these technologies also have their drawbacks and, first of all, it is the price.
It is also worth noting that when the engine is started, the battery voltage drops to about 9 Volts, but the current increases many times - this is a normal process. After starting the engine, the voltage will return to its normal values of 12.7 Volts, and the spent charge will replenish the car's generator. If the voltage at start-up drops to 6 Volts (and takes 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 whether the starter motor has shown. Industrial tests are difficult, often batteries are placed in negative temperatures, cooled for several hours, then they try to start the engine.
Usually the tests take place at - 18 degrees Celsius and the start lasts 30 seconds, if the battery has coped, then it can be put into production. If not, the design, filling is changed, and tests are carried out on a new one.
They are measured several times, that is, there are a number of intervals with maximum values, in such intervals they measure the maximum currents that this particular instance is capable of issuing, they are recorded and later applied to the "boards" of the battery. It should be noted that not all batteries are tested so toughly in a batch. However, there is a "defect", checks are carried out with a load fork.
In fairness, it is worth noting that earlier, during the Soviet era, batteries were not filled with electrolyte at all in production (there was the 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 we charge it within 12 - 24 hours.
What is the starting current of an average battery and what if you buy a high 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, it can reach up to 20 atmospheres.
SO, average indicators:
For gasoline options, this is 255 Amperes
For diesel versions - not less than 300 Amperes
These figures, as stated in the butt, were measured at minus 18 degrees Celsius, which may not be enough when starting in more severe frosts.
But now, with the development of technology, often in stores we can see starting current readings of 400, 500 and even 600 Amperes! What will happen if you take these numbers? Will I burn my starter?
The answer is simple - of course not. Do not burn! Take it and forget what a cold start is, with such characteristics you will not care about any frost.
As for the starter - with a higher current, it will rotate faster and stronger, which will allow it to make more revolutions, and in turn, this contributes to a quick and high-quality engine start.
Of course, you need to read the characteristics of your car, but I think a starting value of 450 - 500 AMP will be enough for all regions of Russia. Again, I'll make a reservation, I'm now considering ordinary non-truck cars with large and voluminous engines, often 600 will not be enough for them.
World classification
As I already touched on a little, there are now several main classifications of starting current values in the world. Which have their own methods of determination and labeling. To begin with, how are they marked:
- German manufacturers stand out here - they affix the "DIN" mark
- In America they apply - "SAE"
- In the countries of the European Union (not Germany) they apply - "EN"
- In Russia, they often write - "starting or starting current"
A car starter battery is a chemical current source that uses reversible electrochemical processes. The simplest lead-acid battery consists of a positive electrode, the active substance of which is lead dioxide (dark brown), and a negative electrode, the active substance of which is spongy lead (gray). If both electrodes are placed in a vessel with an electrolyte (a solution of sulfuric acid in distilled water), then a potential difference will arise between the electrodes.
When connected to the load (consumer) electrodes, an electric current will flow in the circuit, and the battery will be discharged. During the discharge, sulfuric acid is consumed from the electrolyte and, at the same time, water is released into the electrolyte. Therefore, as the lead battery is discharged, the concentration of sulfuric acid decreases, due to which the density of the electrolyte decreases. During charging, reverse chemical reactions occur - sulfuric acid is released into the electrolyte and water is consumed. In this case, the density of the electrolyte increases with the charge. Since the density of the electrolyte changes during discharges and charges, its value can be used to judge the degree of charge of the battery, which is used in practice.
The main electrical characteristics of a battery are electromotive force, voltage and capacity.
The electromotive force (emf) of a battery is the potential difference between its electrodes when the external circuit is open. The value of the emf a working battery depends on the density of the electrolyte (the degree of its charge) and varies from 1.92 to 2.15 volts.
Battery voltage is the potential difference between its terminals, measured under load. For the nominal voltage of a lead-acid battery, a value equal to 2 volts is taken. The voltage value during battery discharge depends on the value of the discharge current, the duration of the discharge and the temperature of the electrolyte; it is always less than the emf. It is unacceptable to discharge the battery below a certain limit, called the final discharge voltage, as this can lead to polarity reversal and destruction of the active mass of the electrodes. The value of the voltage during charging depends mainly on the state of charge of the battery, the temperature of the electrolyte and is always higher than the value of the emf.
The capacity of a battery is the amount of electricity given off by a fully charged battery when it is discharged to its permissible final discharge voltage. Battery capacity is measured in ampere-hours and is defined as the product of the discharge current (in amperes) by the discharge duration (in hours). The battery capacity depends on the amount of active mass (the number and size of electrodes), the value of the discharge current, the density and temperature of the electrolyte, the battery life and is its most important performance characteristic. At high discharge currents, at low electrolyte temperatures, as well as at the end of the service life, the capacity given by the battery decreases. The nominal capacity of the battery is the capacity that the battery must give when discharging with a current of a 20-hour or 10-hour discharge, i.e. at the value of the discharge current, numerically equal to respectively 0.05 and 0.1 of the value of the nominal capacity.
The starter car battery consists of 6 identical batteries connected in series. With this connection, the nominal battery voltage is equal to the sum of the nominal voltages of the individual batteries, and is 12 volts, and the nominal battery capacity remains the same as the capacity of one battery.
Bringing the battery to working condition
| Required density electrolyte, g / cm³ |
Quantity water, l |
Quantity solution sulfuric acid, density 1.40 g / cm³, l |
|---|---|---|
| 1,20 | 0,547 | 0,476 |
| 1,21 | 0,519 | 0,500 |
| 1,22 | 0,491 | 0,524 |
| 1,23 | 0,465 | 0,549 |
| 1,24 | 0,438 | 0,572 |
| 1,25 | 0,410 | 0,601 |
| 1,26 | 0,382 | 0,624 |
| 1,27 | 0,357 | 0,652 |
| 1,28 | 0,329 | 0,679 |
| 1,29 | 0,302 | 0,705 |
| 1,31 | 0,246 | 0,760 |
Automotive storage batteries produced in a dry-charged state must be filled with electrolyte to bring them into working condition, and after impregnation of the electrodes, measure the density of the electrolyte and recharge the battery. At air temperatures down to -15 ° C, electrolyte with a density of 1.24 g / cm³ is poured into the batteries. At temperatures from -15 ° to -30 ° C, the density is increased to 1.26, and below -30 ° - to 1.28 g / cm³.
An electrolyte of the required density can be prepared directly from acid and water. However, it is more convenient to use an acid solution with a density of 1.40 g / cm³. The amount of water and solution required to prepare 1 liter of electrolyte is shown in Table 1. Sulfuric acid is taken into account not in liters, but in kilograms. To convert liters to kilograms, you must use the coefficient 1.83.
The density of the electrolyte is measured with a hydrometer. It consists of a cylinder with a rubber bulb and an intake tube and a densimeter (float). When determining the density of the electrolyte, it is necessary to squeeze the rubber bulb of the hydrometer with your hand, insert the end of the intake tube into the electrolyte and gradually release the bulb. After the densimeter floats up, determine the density of the electrolyte in the battery on its scale. When making measurements, make sure that the densimeter floats freely in the electrolyte (does not “stick” to the cylinder walls).
The density of the electrolyte depends on the temperature. The initial temperature of the electrolyte is 25 ° C. For every 15 ° C change in temperature, the density changes by about 0.01 g / cm³. Therefore, when measuring the density of an electrolyte, its temperature should be taken into account and, if necessary, a correction should be made to the hydrometer readings, using Table 2.
The electrolyte should be poured into the battery with a thin stream using a porcelain, polyethylene or ebonite mug and a glass, polyethylene or ebonite funnel.
| Temperature electrolyte, C ° |
Amendment to indications, g / cm 3 |
|---|---|
| -55 to -41 | -0,05 |
| -40 to -26 | -0,04 |
| -25 to -11 | -0,03 |
| -10 to 4 | -0,02 |
| 5 to 19 | -0,01 |
| 20 to 30 | 0,00 |
| 31 to 45 | +0,01 |
| FROM 46 to 60 | +0,02 |
The electrolyte temperature should not be lower than 15 ° С and not higher than 25 ° С. After filling the electrolyte and impregnating the electrodes no earlier than 20 minutes and no later than 2 hours, the electrolyte density is monitored. If the density of the electrolyte decreases by no more than 0.03 g / cm³ against the density of the filled electrolyte, the battery can be operated. If the density of the electrolyte decreases by more than 0.03 g / cm³, the battery must be recharged. The duration of the first trickle charge depends on the shelf life of the battery in dry state from the moment of manufacture until it is ready for use. The end of the recharge is determined by the constancy of the battery voltage and the density of the electrolyte for 2 hours.
Battery charge
Rechargeable batteries are charged when they are brought into working condition, during a control-training cycle, as well as periodically during operation and at discharges below the permissible limits. In preparation for charging, the density and electrolyte level in all batteries in the battery is measured. In batteries where the level is insufficient, it is brought to normal by topping up with distilled water (but not electrolyte!).
Lead-acid batteries must be charged from a direct current source. In this case, a charger designed to charge one 12-volt battery should provide the ability to increase the charging voltage to 16.0-16.5 V, since otherwise it will not be possible to fully charge a modern maintenance-free battery (up to 100% of its actual capacity). The positive wire (terminal) of the charger is connected to the positive terminal of the battery, the negative to the negative. In the practice of operation, as a rule, one of two methods of charging a battery is used: charge at a constant current or charge at a constant voltage. Both of these methods are equivalent in terms of their impact on battery longevity.
Charging at a constant current is produced by a current equal to 0.1 of the nominal capacity in a 20-hour discharge mode. For example, for a battery with a capacity of 60 Ah, the charging current should be 6 A. To maintain a constant current during the entire charging process, a regulating device is needed. The disadvantage of this method is the need for constant monitoring and regulation of the charging current, as well as abundant gas evolution at the end of the charge. To reduce gas evolution and increase the state of charge of the battery, it is advisable to stepwise decrease the current strength as the charging voltage increases. When the voltage reaches 14.4 V, the charging current is halved (3 Amperes for a 60 Ah battery) and at this current the charge is continued until gas evolution begins. When charging batteries that do not have holes for adding water, it is advisable to decrease the current by half when increasing the charging voltage to 15 V (1.5 A for batteries with a capacity of 60 Ah). A battery is considered fully charged when the charging current and voltage remain unchanged for 1–2 hours. For modern maintenance-free batteries, this state occurs at a voltage of 16.3-16.4 V, depending on the composition of the lattice alloys and the purity of the electrolyte (at its normal level).
The electrolyte temperature rises during battery charging, therefore it is necessary to control its value, especially towards the end of the charge. Its value should not exceed 45 ° C. If the temperature turns out to be higher, the charging current should be halved or the charge should be interrupted for the time required for the electrolyte to cool down to 30 ... 35 ° С.
If the density of the electrolyte differs from the norm by the end of the charge, it is necessary to correct it by adding distilled water in cases where the density is higher than the norm, or adding a solution of sulfuric acid with a density of 1.40 g / cm³ when it is below the norm. The density adjustment can be done only at the end of the charge, when the density of the electrolyte no longer increases, and due to "boiling" fast and complete mixing is ensured. The amount of electrolyte withdrawn and added water or acid solution for each battery can be determined using the data in Table 3. After the adjustment, continue charging for 30-40 minutes, then measure the density again, and if it differs from the norm, carry it out again.
| 1,24 | 1,25 | |||||
| Electrolyte suction | Topping up solution 1.40 g / cm 3 | Topping up water | Electrolyte suction | Topping up solution 1.40 g / cm 3 | Topping up water | |
| 1,24 | - | - | - | 60 | 62 | - |
| 1,25 | 44 | - | 45 | - | - | - |
| 1,26 | 85 | - | 88 | 39 | - | 40 |
| 1,27 | 122 | - | 126 | 78 | - | 80 |
| 1,28 | 156 | - | 162 | 117 | - | 120 |
| 1,29 | 190 | - | 200 | 158 | - | 162 |
| 1,30 | - | - | - | - | - | - |
| The density of the electrolyte in the battery, g / cm 3 | Required density, g / cm 3 | |||||
| 1,26 | 1,27 | |||||
| Electrolyte suction | Topping up solution 1.40 g / cm 3 | Topping up water | Electrolyte suction | Topping up solution 1.40 g / cm 3 | Topping up water | |
| 1,24 | 120 | 125 | - | 173 | 175 | - |
| 1,25 | 65 | 70 | - | 118 | 120 | - |
| 1,26 | - | - | - | 65 | 66 | - |
| 1,27 | 40 | - | 43 | - | - | - |
| 1,28 | 80 | - | 86 | 40 | - | 43 |
| 1,29 | 123 | - | 127 | 75 | - | 78 |
| 1,30 | - | - | - | 109 | - | 113 |
| To use the table, its data must be multiplied by the volume of one battery of the battery, expressed in liters. | |||||||||
| The density of the electrolyte in the battery, g / cm 3 | Required density, g / cm 3 | ||||||||
| 1,29 | 1,31 | ||||||||
| Electrolyte suction | Topping up solution 1.40 g / cm 3 | Topping up water | Electrolyte suction | Topping up solution 1.40 g / cm 3 | Topping up water | ||||
| 1,24 | 252 | 256 | - | - | - | - | |||
| 1,25 | 215 | 220 | - | - | - | - | |||
| 1,26 | 177 | 180 | - | 290 | 294 | - | |||
| 1,27 | 122 | 126 | - | 246 | 250 | - | |||
| 1,28 | 63 | 65 | - | 198 | 202 | - | |||
| 1,29 | - | - | - | 143 | 146 | - | |||
| 1,30 | 36 | - | 38 | 79 | 81 | - | |||
The operational electrolyte level is set after the end of the density correction and not earlier than 30 minutes after the batteries are turned off from the charge. If the electrolyte level is below the norm, electrolyte of the same density must be added to the battery.
When charging at a constant voltage, the state of charge of the battery at the end of the charge directly depends on the value of the charging voltage provided by the charger. So, for example, for 24 hours of continuous charge at a voltage of 14.4 V, a fully discharged 12-volt battery will charge by 75-85%, at a voltage of 15 V - by 85-90%, and at a voltage of 16 V - by 95-97% ... It is possible to fully charge a discharged battery within 20-24 hours at a charger voltage of 16.3-16.4 V. At the first moment of switching on the current, its value can reach 40-50 A or more, depending on the internal resistance (capacity) and depth battery discharge. Therefore, the charger is equipped with circuitry that limits the maximum charging current. As the charge progresses, the voltage at the terminals of the battery gradually approaches the voltage of the charger, and the value of the charging current, accordingly, decreases and approaches zero at the end of the charge. This allows charging without human intervention in a fully automatic mode. Erroneously, the criterion for the end of the charge in such devices is the achievement of the voltage at the terminals of the battery when it is charged, equal to 14.4 ± 0.1 V. In this case, as a rule, a green signal lights up, which serves as an indicator of reaching the specified final voltage, that is, the end of the charge. However, for a satisfactory (90-95%) charge of modern maintenance-free batteries using similar chargers with a maximum charging voltage of 14.4-14.5 V, it will take about a day.
The accelerated combined charging method is used when it is necessary to fully charge the batteries in a short time. The accelerated combined charge is produced in two stages. At the first stage, the batteries are charged at a constant charging voltage, at the second stage - at a constant charging current. The transition to charging batteries at a constant value of the charging current is carried out when it decreases at the first stage of charging to a value of 1/10 of the capacity.
Control-training cycle
The control and training cycle is carried out to control the technical condition of the batteries, check the capacity they give, and correct lagging batteries. Lagging are those batteries, the parameters of which are lower than the rest.
In the control-training cycle, the following are carried out:
- preliminary full charge;
- control (training) discharge with 10-hour current;
- final full charge.
A preliminary full charge at KTC is carried out by a charging current equal to 1/10 of the battery capacity. Before the start of the control discharge, the electrolyte temperature should be 18 ... 27 ° C. The value of the discharge current for storage batteries must correspond to the value indicated in table 4.
The constancy of the discharge current must be carefully observed throughout the entire discharge. The discharge is carried out to a final voltage of 10.2 V. When the voltage drops to 11.1 V, measurements are made every 15 minutes, and when the voltage drops to 10.5 V, measurements are made continuously until the end of charging.
The calculation of the capacity given by the storage battery, as a percentage of the nominal, is carried out by. The actual capacity given during the check discharge can be either less or more than the nominal one. The final full charge of car batteries is carried out with a normal charging current in compliance with all the rules with the adjustment of the electrolyte density at the end of the charge.
Battery capacity concept
Battery capacity is one of its most important technical characteristics. This term is understood as the amount of time that the source of autonomous energy is able to supply to the electrical consumers connected to it. In other words, this is the maximum amount of electricity accumulated by the battery during a full charge cycle. The unit of measure for capacity is Ah (ampere-hour), for small batteries it is mAh (milliampere-hour).
An example of calculating the required capacity
As you know, the calculation of the consumed power is made in W, and the battery capacity for the UPS is in Ah. To calculate the required battery capacity for powering a particular technique, it is necessary to make some recalculation. For a better understanding, consider a specific example. Let's say you have a critical load of 500 watts that needs to be backed up for 3 hours. Since the amount of accumulated energy depends not only on the capacity of the battery, but also on its voltage, for the calculation we divide the total power of the redundant equipment by their operating voltage (often confused with the open circuit voltage of a fully charged battery). For a standard 12V battery, the required battery capacity is:
Q = (P t) / V k
where Q is the required battery capacity, Ah;
V is the voltage of each storage battery, V;
t is the backup time, h;
k is the utilization factor of the battery capacity (the amount of electrical energy allowed for use by consumers).
The need to introduce a coefficient is due to the possibility of incomplete battery charging. In addition to this, a strong (deep) discharge following a small number of charge and discharge cycles leads to premature wear and damage of the battery. For example, if a new battery is discharged by 30% of its total capacity, and then immediately recharged, it can withstand about 1000 such cycles. If the discharge value decreases to 70%, then the number of these cycles will decrease by about 200.
In total, we find that to power a given load for a specified period of time, it will take:
Q = 500 3/12 0.7 = 178.6 Ah.
This is the minimum required battery capacity for the case under consideration. Ideally, it is better to take a power source with a small margin (about 20%) in order not to completely discharge it every time - this will help maintain the performance of the battery for as long as possible.
Q = 178.6 * 1.2 = 214.3 Ah.
This means that to solve the problem, it is necessary to purchase batteries with a total capacity of at least 215 Ah. When using a UPS in tandem with a generator, it is recommended to reduce the capacity correction factor to 0.4, since in such a bundle, batteries are most often used to maintain continuous power supply until the power plant is turned on and the entire load is transferred to it. In this case, if the value of the coefficient 0.4 is to include the loss of battery capacity during its aging, due to the peculiarity of the pulse converter and others, then on average the discharge of the battery can reach 50% of its nominal capacity.
In the case when several batteries are used to back up the load, the amount of energy accumulated in them does not depend at all on the type of their connection - parallel, serial, or mixed. Given this feature, it is necessary to substitute the voltage of one battery in the formula for determining the total capacity of the batteries, but at the same time it is allowed to use only batteries with the same technical characteristics.
Battery indicators, with which the concept of capacity is inextricably linked
- Dependence of battery capacity on its discharge current.
This dependence is based on the following fact: when the protected load is connected to the battery without using a converter, then the amount of current consumed by the battery is unchanged. In this case, the operating time of the connected electrical consumers will be determined as the ratio of the taken capacity to the consumed current. In a more familiar form, this formula is written as follows:
where Q is the battery capacity, Ah (mAh);
T - battery discharge time, h.
If we are dealing with large values of the consumed current, then the real power indicators are often lower than the nominal ones indicated in the passport.
- Dependence of battery capacity on energy
Today, among users, the opinion is quite widespread that the capacity of a storage battery is a value that fully characterizes its electrical energy, accumulated in the battery 100% charged. This statement is not entirely correct. Here it is also necessary to make a reservation that the ability to store energy in a battery directly depends on its voltage and the higher it is, more energy can be stored by the battery. In fact, electrical energy is defined as the product of the charging current, battery voltage and the time that this current flows:
where W is the energy accumulated by the battery, J;
U - battery voltage, V;
I is the constant discharge current of the battery, A;
T - battery discharge time, h.
Based on the fact that the product of the current and the charging time gives us the capacity of the battery (as discussed above), it turns out that the electrical energy of the battery is found by multiplying the nominal voltage of the battery and its capacity:
where W is the energy accumulated by the battery, Wh;
Q - battery capacity, Ah;
U - battery voltage, V.
When several batteries of the same capacity are connected in series, the total indicator of this bundle is equal to the sum of the capacities of all the batteries included in its composition. In this case, the energy of the resulting accumulator unit is determined as the product of the electric power of one battery by their number.
- The concept of the energy capacity of the battery
An equally useful indicator of storage batteries for the consumer is their energy capacity, measured in units such as W / cell. This concept characterizes the capacity of the battery for a certain short period of time, which is most often no more than 15 minutes, in constant power mode. This indicator is most widespread in the United States, but recently it is gaining popularity among consumers in many other countries. For an approximate calculation of the capacity of a storage battery, measured in Ah by the value of its energy capacity in W / cell for a period of 15 minutes, use the formula:
W is the energy capacity of the battery, W / cell.
- Battery backup capacity
For car batteries, another characteristic is distinguished - a reserve capacity, which indicates the ability of the battery to power the electrical equipment of a moving car when the vehicle's standard generator is not working. This parameter is also better known in the USA and is called "reserve capacity". It is measured in minutes of battery discharge with a current of 25 A.
where Q is the battery capacity, Ah;
T - battery backup capacity, min.
Battery capacity and charge (charge)
Another fairly popular misconception is the identification of the concepts of battery capacity for and its charge (charge). Let's dot all the "and". Capacity is understood as the maximum potential of the battery, that is, the amount of energy that it can store in a fully charged state. The charge, in turn, represents this energy required to power the load in autonomous mode. Hence the conclusion that the amount of charge of the same battery can be different depending on the charging time of the battery, and the value of its capacity in the discharged and charged states is the same. Here you can draw an analogy with a glass into which water is poured. The volume of the device will represent a container - this is a value that does not depend on whether the glass is full or empty, and the most poured water is a charge.
What other factors do the battery capacity depend on?
Discharge current
Those battery capacity indicators that can be found in their technical documentation and on the product case are indicated by the manufacturer based on the results of test measurements made according to the above formula (Q = I T) with a standard discharge duration (10, 20, 100 hours, etc.). etc.). Accordingly, the capacity is also designated - Q10, Q20 and Q100, as well as the discharge current - I10, I20 I100. In this case, the amount of current flowing through the load at a discharge time of 20 hours is determined by the formula:
Following this logic, we can assume that with a discharge lasting a quarter of an hour (15 minutes), the current will be equal to Q20 x 4. However, this is not the case, as practice shows, in the case of a 15-minute discharge, the capacity of a standard lead battery will be no more than half of its nominal capacity ... Accordingly, the value of the parameter I0.25 will be slightly less than Q20 x 2. Hence, we can conclude that characteristics such as time and discharge current are not proportional to each other.
End discharge voltage
Each time the battery is discharged, the voltage on it gradually drops, and upon reaching the so-called final discharge voltage, it is imperative to disconnect the battery. Moreover, the lower this characteristic is, the correspondingly higher will be the actual capacity of the battery. As a rule, manufacturers indicate on their own batteries the minimum value of the final discharge voltage, which in turn depends on what current the discharge is made with. There are situations when the voltage of the energy source drops below this value (they forgot to disconnect the battery in time or this could not be done, since it was impossible to de-energize the load for a long period). Then there is a phenomenon called deep discharge of the battery. If the battery is frequently discharged deeply, it can quickly fail.
Battery wear
It is generally believed that a new battery has a nominal capacity (the one indicated by the manufacturer). However, the real value of this indicator may differ slightly - be less than the declared value due to long-term storage in the warehouse, or after several full charge and discharge cycles and a short operation in the buffer mode, it will slightly increase. Further operation of the battery, as well as its storage, invariably lead to physical deterioration of the energy source, its aging and gradual failure.
Temperature
Such an important factor as the ambient temperature in the place where the battery is used has a very strong effect on the capacity of the latter. In the case of an increase in temperature from 20 ° C to 40 ° C, the battery capacity indicator increases by 5%, and when it decreases to 0 ° C, it decreases on average by 15%. A further decrease in the air temperature leads to a drop in the specified parameter by another 25% relative to the nominal value.
How do I check the battery capacity?
Very often, the owner of a used battery is faced with the task of determining its residual capacity. The classic and must be given tribute to the most reliable and effective way to check the actual capacity of the battery is a test discharge. This term means the following procedure. The battery is first fully charged, after which it is discharged with a constant current, while the time for which it is completely discharged is measured. After that, the battery capacity is calculated according to the already known formula:
For greater accuracy of the calculation, it is better to select the value of the constant discharge current in such a way that the discharge time is about 10 or 20 hours (this depends on the discharge time at which the nominal capacity of the battery was calculated by the manufacturer). Then the data obtained is compared with the passport data, and if the residual capacity is 70-80% less than the nominal, the battery must be replaced, since this is a clear sign of strong battery wear and its further wear will proceed at an accelerated rate.
The main disadvantages of this method are the complexity and laboriousness of implementation, as well as the need to remove batteries from service for a sufficiently long period of time. Today, most devices that use rechargeable batteries for their work have a self-diagnostic function - a quick (in just a couple of seconds) check of the status and operability of energy sources, but the accuracy of such measurements is not always high.
The operating period of a battery usually does not exceed four years, so sooner or later the question of choosing a new battery for the car arises before car owners. But how do you know which type of battery to choose? What characteristics should be guided by? And where can you find their description? We will tell you about this today.
Battery and its types
There are several main types of rechargeable batteries, which differ in the material from which the electrodes are made and the composition of the electrolyte. Many of you know that there are various nickel-cadmium, nickel-metal hydride, lithium-ion, lead-acid batteries. From this list, only one is used as starter - lead. This is due to the fact that this type of rechargeable batteries is endowed with the largest possible reserve of electrical capacity, in comparison with others, and is capable of instantly delivering a large current.
But with all this, you have to put up with the fact that their filling is very harmful, because it is lead and acid. To ensure maximum safety of operation of lead-acid batteries, their bodies are made of special plastic that is resistant to acid. Today, the material from which the electrodes are made is lead, not in pure form, of course, but with various additives, on which the further division of batteries into several types depends:
- Traditional, which are also called antimony;
Low antimony;
Calcium;
Hybrid;
Gel or AGM;
Alkaline;
Traditional or antimony
Rechargeable batteries of this type as part of lead electrodes also contain 5%
antimony. They are also called simply classic or traditional. But today the relevance of these names no longer makes direct sense, because the content of antimony has decreased significantly. Antimony is added to the alloy in the composition of the electrodes to increase their strength. But this additive also speeds up the electrolysis process, starting as early as 12 volts. A large number of gases are released and there is a feeling of boiling water. Due to the evaporation of water in large volumes, the electrolyte changes its concentration to a stronger one, due to which the top of the electrodes is exposed. In order to restore the water balance of the electrolyte, distilled water is added to it.
Batteries with a high content of antimony additives are very easy to maintain. This is due to the fact that monthly it is necessary to check the concentration of the electrolyte and, if necessary, fill in distilled water. In new car models, such batteries are no longer installed, because progress is rapidly advancing. These batteries are still installed on immovable installations, where simplicity is important and there are no problems with servicing power supplies. Car batteries are now made without the addition of antimony, or their amount is minimized to the maximum.
Low antimony
To avoid strong evaporation of water from the electrolyte, battery plates, as mentioned above, began to be made with minimal antimony additives, the amount of which does not reach 5%. As a result, the frequent need to check the electrolyte concentration level has sunk into oblivion. Self-discharge also decreased during long-term storage of the battery.
This type of battery is one that has little or no maintenance. This is justified by the fact that the insides of the battery do not need control and maintenance. Although in essence such a term as "unattended" refers to an unrealized theory or, most likely, to cunning marketing operations, they have not yet reached the level at which the water from the electrolyte does not boil away at all. It evaporates a little anyway, albeit in much smaller volumes than those of those batteries that are called serviced.
Calcium
Manufacturers are still struggling with how to make a completely maintenance-free battery so that the water in it does not evaporate at all. For this, the antimony in the lattices of the electrode plates was replaced by another, more suitable material. This turned out to be calcium. Calcium-type batteries are often marked with the letters "Ca / Ca". This designation tells car owners that the plates of both poles contain calcium.
In addition, silver is sometimes added to the composition of the electrodes in very small quantities. This reduces the resistance inside the battery, which has a good effect on its performance and energy consumption. Calcium in the composition of lead plates perfectly coped with the task of reducing gas evolution and loss of water, which puts this type an order of magnitude higher than low antimony batteries. The loss of water during the operation of the battery is so negligible that the need to check the electrolyte concentration and its level in the banks simply became unnecessary.
Thus, calcium-type storage batteries can rightfully be called maintenance-free. In addition to less water loss, calcium batteries also have a 70% lower self-discharge level compared to previous opponents. This allows these batteries to maintain their performance for a longer period. Such batteries are installed in factories for the production of foreign cars of the middle price segment, where the manufacturer boldly guarantees the stability and quality of electrical equipment.
But when buying a battery of this type, be aware that more careful care is required than a low antimony one. But with proper maintenance, you will have a reliable and stable high quality power supply.
Hybrid
The battery data type is marked as "Ca +". Hybrid storage batteries have electrode plates that are created using various technologies: the positive electrodes are low in antimony, and the negative ones are already calcium. This technology has made it possible to combine both types of negative sides in one battery. Hybrid batteries consume water 50% slower than low-antimony batteries, but still faster than calcium batteries. But on the other hand, hybrids are much more resistant to overcharging. According to their characteristics, they rightfully occupy a niche between the two previous representatives.
Gel or AGM
Banks of gel batteries are filled with electrolyte not in a liquid state that we understand, but in a gel-like, fixed state, which is where the name of this type comes from. Due to this state of the electrolyte, these batteries are not afraid of slopes, because the gel is not as liquid as the liquid. Although this is again a professional "tempting" marketing ploy, and it is better not to overturn gel-filled batteries. Although manufacturers write that such batteries can be operated in any convenient position.
The excellent vibration resistance does not end with the positive aspects of AGM batteries. They are also slow to self-discharge, so they endure long-term storage without fear of a critical decrease in charge. They should be stored in a fully charged state.
The strength of the current supplied by the battery, depending on the charge, remains unchanged even before complete discharge. They are also not afraid of overdischarge, they completely restore their previous capacity even after recharging. But with the charge of gel-type batteries, the situation is not as smooth as with the discharge. Such batteries cannot be overcharged. They must be charged with a very low current. For this, even chargers are produced, specially adapted for charging gel batteries.
The market is rich in universal chargers though, which are scheduled to charge any type of battery. It is impossible to answer unequivocally how much this is all true, because manufacturers are different and it is better to pay attention to those who have already established themselves in the market and have firmly established themselves.
The negative side of gel batteries is their "fear" of extremely low temperatures. The lower the ambient temperature, the lower the conductivity of the gel electrolyte becomes. If operating conditions are favorable, these batteries can last for ten years.
Alkaline
Did you know that electrolyte in batteries can have not only acidic but also alkaline constituents? And there are many varieties of such batteries, but we will take for consideration only those that are used in cars.
But car alkaline batteries are of only two types: nickel-cadmium and nickel iron. Batteries of the first type have positive electrodes coated with nickel hydroxide NiO (OH), and negative electrodes coated with iron doped with cadmium. In the second type of battery, the positive electrodes are coated identically to those found in a nickel-cadmium battery, that is, nickel hydroxide. But in the negative electrode there are already differences, here it is made of pure, no impurities, iron. The alkaline electrolyte in both types of batteries is a potassium hydroxide solution.
This and the last type of rechargeable batteries in our list is considered the most promising today. The electrolyte of this type of battery contains lithium ions. It will not be possible to say unequivocally about what material the electrode plates are made of, because the manufacturing technology is moving forward all the time. However, we know that initially they were produced from metallic lithium, but due to their explosiveness, such electrodes were no longer used. They were replaced by graphite plates. For positively charged electrodes, lithium oxide was used with the addition of cobalt or manganese. But at the present time they are being replaced by lithium-ferro-phosphate, because the new material is much less toxic, more accessible and environmentally friendly. Such plates can be safely disposed of.
Work is constantly underway to improve the existing types of batteries, and it is continuous. R&D centers work tirelessly to find more power-hungry, compact power supplies. For regions with extreme winters, the invention of batteries resistant to severe frosts would be useful, then the problem with engine failure would be solved. The movement towards environmental friendliness is also important. After all, today they have not yet learned how to produce completely environmentally friendly storage batteries.
So far, we cannot do without the addition of toxic elements, such as, for example, lead, alkali, sulfuric acid. But with traditional batteries, the future is likely closed. Gel batteries are an intermediate evolutionary stage. The battery of the future is seen without filling with liquid, of arbitrary shape, as well as with many other parameters that will save car owners from worries about whether the electrolyte has spilled out, and whether the battery will fail. The driver should enjoy the ride.
Specifications: weight, amperage, capacity, voltage
The most important indicators of the quality of rechargeable batteries are: voltage, weight, capacity, dimensions, nominal discharge depth, service life, efficiency, operating temperature range, permissible charge and discharge current. Also consider the fact that the characteristics indicated by the manufacturer are valid for temperatures of 20-25 degrees Celsius. With deviations from these numbers, they change and often not for the better.
The voltage and capacity values are often used in the name of the battery model. So, for example, the RA12200DG battery. The battery voltage is 12 Volts, its capacity is 200 A / h, gel electrolyte, deep-discharge. This battery delivers 2.4 kW of energy, based on the formula 12 x 200 = 2400 W * h when discharged with a current for ten hours at 10% of the total capacity. With deviations in the direction of a higher current and a quick discharge, the capacity of such a battery decreases. At lower currents, on the contrary, it often increases. You need to look at the discharge characteristics of those or other batteries that interest you. Sometimes manufacturers in the name indicate too ideal battery capacity, which is possible only in utopian conditions. Such amateurs, for example, Haze, whose capacity in reality is an order of magnitude lower than the declared one, namely by 10-20 points, and this is significant, you must agree.
Battery capacity
The amount of energy that a rechargeable battery can store in itself is called its capacity. It is measured in ampere-hours A / h. For example, a single battery with a capacity of 100 ampere hours can supply 1 ampere for 100 hours, or 5 amperes for 20 hours, and so on. Although the capacity of the battery decreases if the discharge current increases. On the market, you can buy batteries with a capacity of 1 to 2000 A / h.
Life time
In order to extend the life of a lead-acid battery, it is best to use only a small portion of its capacity before recharging. Each process that is accompanied by the discharge and recharge of the battery is called a charging cycle, and it is not necessary to completely discharge the battery. Let's say you discharged the battery by a quarter, and then you charged it again, then it had one charging cycle. But the number of cycles will directly depend on the depth of discharge.
If the battery can be discharged more than half of its nominal capacity without significant deterioration in its parameters, then such a unit is called "deep-discharge". The battery can be damaged if it is charged more than necessary. The maximum voltage supplied to a 12 volt acid battery should not exceed 15 watts. A significant part of photovoltaic batteries have a soft load characteristic, therefore, with an increase in voltage, the charging current decreases significantly. Let's say you always need to use a specific charge controller for solar panels. It is also necessary to use it for wind power plants and micro-hydroelectric power plants.
Voltage
Battery voltage is often the main parameter, which can be monitored to determine how much the battery is charged and in what state it is. This is especially true for batteries in a sealed shell, in which it is physically impossible to measure the electrolyte concentration without damaging them. In order to determine how much, its voltage is measured at the terminals for 4-5 hours in the absence of charging and discharging currents.
The voltage measured during charging or when the battery is discharged will not tell anything about how charged the battery is. The dependence of how much the battery is charged on the voltage on it in idle mode is different for different types of batteries. For batteries that are sealed, for example, there are slightly more gel types than for those types that have a liquid electrolyte in them. For example, an AGM battery is considered fully charged if its voltage is 13 watts, while for acid batteries it is 12.5 watts.
State of charge
How much the battery is charged depends on many factors. And only special devices with memory and a microprocessor are able to accurately determine the battery charge. They monitor the charge and discharge of the battery over several charging cycles. Using this method will give you the most accurate readings about the battery charge, but it will also take a considerable amount of money. But do not skimp on the use of this method, because you can avoid unnecessary expenses with further maintenance and replacement of the battery. By using special devices that control the operation of the batteries according to their state of charge, you will significantly increase the operating period of your lead-acid battery.
To determine how much your car's battery is charged, the following two methods are also successfully used, which are simplified.
Battery voltage
This method is not very accurate, but its use requires only a digital voltmeter, with a sensitivity of up to a hundredth of a volt. Before starting measurements, it will be necessary to disconnect the battery from all consumers of electricity that discharge it and from the devices that charge it. Wait at least two hours and start measuring on the battery terminals. A 100% charged gel battery will have a voltage of 13 watt against 12.5 watts for liquid electrolyte batteries. As the battery begins to age, its voltage decreases. The voltage can be measured both on the entire battery and on each bank. To find a faulty one, for example, in a 12-volt battery, you need to divide the total voltage by the number of cells, in this case 6.
Electrolyte density
The next method for checking the charge of a battery is by the density of the electrolyte. As it has already become clear, it is suitable only for liquid-filled batteries, for gel, for example, it cannot be used a priori. Also, as in the first method, you need to wait at least two hours before starting measurements. Measurements are made with a hydrometer. Important! Before starting the procedure, be sure to protect yourself by wearing gloves and plastic safety glasses. Keep baking soda and water handy in case electrolyte gets on your skin.
Battery life
Determining the operational period by time intervals is not entirely correct. Battery life is measured in charge cycles and depends directly on the operating conditions. The greater the depth of discharge of the battery and the longer it is in a discharged state, the more significantly the number of its working cycles is reduced.
As we already understood, the concept of the number of charging cycles is absolutely relative, because it depends directly on many factors. In addition, the number of life cycles of one battery will not be the same for another, this concept is not universal. After all, everything again depends on the operating factors and production technology, which differs from one manufacturer to another. Remember that battery life is based on charge cycles, and times are approximate if the battery is used continuously under typical conditions.
Another important point is that the useful battery capacity decreases during the operation of the battery. All characteristics in terms of the number of cycles are determined not until the complete death of the battery, but until it loses 40; from its nominal capacity. For example, if the manufacturer indicated the number of 600 cycles with a charge equal to half of its capacity, this means that after 600 identical cycles under ideal conditions, the useful capacity of the battery will be 60% of the factory one. And already with this value of capacity, manufacturers recommend replacing the battery. Lead acid batteries have a lifespan ranging from 300 to 3000 cycles, depending on the type and depth of discharge of the battery.
In order to ensure a long service life, the discharge of the battery in a typical cycle should not exceed 30% , and deep discharge - 80% capacity. If a lead acid battery is discharged, it needs to be recharged faster. If such a battery has been in a completely discharged or undercharged state for more than 12 hours, then the consequences that happened to it can be irreversible and its service life will sharply decrease.
How can you tell if a battery is already nearing its limit? Everything is very simple. The internal resistance of the battery rises sharply, which leads to a voltage surge during charging, as a result of which the charging period itself is reduced and the battery is discharged more quickly. If you start charging a dying battery with a current that is close to the limit, then it will get very hot, much stronger than before.
Maximum charge and discharge currents
Charge and discharge currents of any battery are measured depending on its capacity. As a rule, the maximum charging current for a storage battery should not exceed more than 0.3C. Exceeding the charge current will lead to a decrease in the operating life of the battery. We recommend setting the charging current to no more than 0.2C.
Self-discharge
Self-discharge, as a phenomenon, is characteristic of all types of storage batteries to a lesser or greater extent and consists in the loss of their capacitive characteristics after they have been fully charged in the absence of an external energy consumer. In order to make it convenient to quantify the self-discharge of the battery, it will be convenient to use the value of the lost capacity for a certain period of time, which is expressed as a percentage of the value obtained immediately after a full charge. For the time period, as a rule, an interval is taken that is equal to one day or one month.
For example, if you take a serviceable NiCD battery, then their admissible self-discharge is 10% per day after charging. For NiMH batteries - a little more, but for Li-ION it is completely small and is estimated in a month. In lead-acid batteries, the self-discharge is already calculated in years, for it is much reduced and amounts to 40% per year at a temperature of 20 degrees Celsius and 15% at a temperature of 5 degrees. If the storage temperature is much higher, then self-discharge is also faster.
For example, at a temperature of 40 degrees, the battery will lose its 40% capacity in 5 months. Note that the battery is highly self-discharging only in the first day after charging, and then it dies down significantly. If the battery is subjected to deep discharge and subsequent charging, then this aggravates its self-discharge. The self-discharge process gains strength at elevated temperatures. So, for example, if the ambient temperature rises sharply by 10 degrees, in relation to the usual, then the self-discharge will double.
The capacity can also be wasted in the event of damage to the separator, when the crystals stick together, forming a large lump that breaks through it. The separator in the battery is a thin plate that separates the positive and negative electrodes. This happens when the battery is improperly maintained or not maintained at all. This can also happen if you use low-quality charging devices or those that do not meet the required parameters. If the battery is worn out, then its electrode plates stick to each other due to their swelling. This leads to an accelerated self-discharge. At this stage, the damaged separator can no longer be repaired by charging / discharging.
Marking - find out the charge capacity, current and other parameters
exists so that you, as a buyer, could receive the detailed necessary information about all the necessary technical characteristics of the battery you are interested in. It includes: battery type, trademark and production date, weight and compliance with GOST. The number of combined batteries in a single battery is also indicated, as a rule there should be 3 or 6. The letters "St" tell you that you are observing an old battery in front of you. Depending on the material of manufacture of the monoblock case, the corresponding letter is indicated:
NS- ebonite;
NS- asphalt plastic;
T- thermoplastic.
The material from which the separators are made is also important. If there is a capital letter in the marking "R" then this is mipora, letter "M" points to miplast, and "WITH" is fiberglass.
The voltage, as such, is not indicated in the labeling of the battery, it is simply not necessary, because it is a standard value that can be measured with a conventional load plug. Pay also your attention to the presence of the letter "Z", if any. If present, this indicates a flooded battery that is fully charged. If this letter is absent, then the battery is dry-charged.
