How to equalize the voltage in battery banks. Preventative maintenance and charging of traction batteries. Corrosion and shedding of the active substance
8.1. Constant charging mode.
All AB in electrical networks and substations must be operated in constant recharging mode.
A fully charged battery must be connected to the buses in parallel with a constantly running charging unit. The charging unit supplies the load direct current and at the same time recharges the battery, compensating for its self-discharge. End AEs must also operate in constant recharge mode.
When a powerful jolt load is turned on, as well as when the charging unit loses power from the alternating current side, the battery takes over the entire load of the DC network.
In emergency modes, the battery must also ensure operation necessary equipment ES or PS for at least 1 hour with the required voltage level of the design mode.
For an SK type battery, the charging voltage should be 2.20 ± 0.05 V per AE.
For batteries type SN, the recharging voltage should be 2.18 ± 0.04 V per AE at an ambient temperature not higher than 35 °C. If the temperature is higher, the voltage should be 2.14 ± 0.04 V.
For batteries from different companies that use the main types of batteries (Vb VARTA, OPzS, GroE, etc.), the charging voltage should be 2.23 ± 0.005 V per AE at an ambient temperature of 20 ° C. For other types of branded AEs (FIAMM, OGi, etc.), the recharging voltage must meet the requirements of the technical documentation for the specific type of AE of the manufacturer or supplier ((2.27 ± 0.03) V; 2.27 V ± 1% ; 2.23 V ± 1%, etc.).
The voltage spread across individual AEs within the battery in the recharging mode should not exceed plus 0.1 V/minus 0.05 V from the recharging voltage.
The spread of electrolyte temperatures should be no more than 3°C compared to the average temperature of the battery electrolyte. The average temperature of the battery should not exceed the temperature of the ambient air (medium) by 3 °C.
The charging installation must ensure stabilization of the voltage on the battery with deviations that do not exceed the requirements established by the manufacturer, and for branded batteries - no more than ± 1% of the rated voltage (or the requirements established by supplier companies).
The specific current and voltage values required cannot be set ahead of time. It is necessary to establish and maintain an average value of the charging voltage and monitor the battery. A decrease in electrolyte density in most batteries indicates insufficient recharging current. In this case, as a rule, the required recharging voltage is 2.25 V for SK type batteries and not lower than 2.20 V for CH type batteries.
8.2 Charge mode.
Subject to compliance with operating requirements, and also depending on the condition of the battery, local conditions, the availability of appropriate types of chargers (units), and the availability of time, it is permissible to use any known charging methods and their modifications:
- at constant current;
- with a smoothly descending current strength;
- at constant voltage, etc.
The charging method is established by the company's instructions.
In this case, there should be no conditions under which, for specific types of AE, unacceptable voltages and charge currents, excess of the electrolyte temperature and processes of intense gas formation may occur.
During charging, the necessary parameters to monitor the condition of the batteries should be measured and recorded at appropriate intervals.
Charging at a constant current must be performed in one or two degrees.
With a two-stage charge, the first stage current should not exceed 0.25C10 for SK type batteries, 0.2C10 for CH type batteries, and 0.7C10 for branded batteries, depending on the type (until a voltage of 2.40 V is reached at the AE).
When the voltage increases (reaches) up to 2.30-2.35 V/cell. for conventional and 2.40 V on AE for branded ones, the charge is transferred to the second stage, the charge current should be no more than: for batteries of type SK - 0.12C10, for batteries of type SN - 0.05C10 and for branded batteries - 0, 35С10.
With a single-stage charge, the current should not exceed a value equal to 0.12C10 for batteries of types SK and CH and 0.15C10 for branded batteries. Charging SN type batteries with a current of 0.12C10 is allowed only after emergency discharges.
The charge is carried out to a constant voltage and electrolyte density for 1 hour for SK type batteries and for 2 hours for SN type batteries.
Branded batteries are charged to a constant voltage of 2.6-2.8 V/cell. and electrolyte density 1.24 ± 0.010 g/cm3 (reduced to a temperature of 20 °C) for 2 hours.
When charging branded batteries using a gradually decreasing current method until a voltage of 2.4 V/cell is reached. charging current is not limited. At a voltage of 2.40 V/cell. the charge current should not exceed 0.15C10, and at a voltage of 2.65 V/cell. - 0.035С10.
Charging at a constant voltage must be carried out in one or two degrees.
The charge in one stage is carried out at a constant voltage of 2.15-2.35 V on AEs of conventional types SK and SN. In this case, the initial charge current may exceed the value of 0.25C10, but then it automatically decreases to the level of 0.05C10.
Branded batteries are charged at a constant voltage of 2.25-2.30 V/cell, with the initial charge current being (0.1-0.3)C10.
Charging in two stages of conventional types is carried out in the first stage with a current that does not exceed 0.25C10, up to a voltage of 2.15-2.35 V on the AE, and then at a constant voltage - from 2.15 to 2.35 V/cell.
Branded batteries at the first stage are charged with a current of (0.1-0.15)C10 until a voltage of 2.35 V/cell is reached, and at the second stage a constant charge voltage of 2.23 V ± 1% is maintained, while the charging current automatically gradually decreases. The charge ends when the voltage and density of the electrolyte on the AE reach constant values for 2 hours.
Charging batteries with an elemental switch must be carried out in accordance with the instructions of the enterprise.
During charging, the voltage at the end of the charge can reach 2.60-2.70 V/cell; the charge is accompanied by strong “boiling” of the battery electrolyte, which will cause increased wear of the electrodes and a reduction in service life, especially for branded batteries.
For all charges, the batteries must have at least 115% of the capacity removed from the previous discharge.
During charging, it is necessary to measure the voltage, temperature and density of the battery electrolyte in accordance with Table 8.
Before turning on, 10 minutes after turning on and after the end of charging, before turning off the charging unit, it is necessary to measure and record the parameters of each battery, and during charging - of the control batteries. The charge current, cumulative capacity and charge date are also recorded.
The electrolyte temperature during charging of SK type batteries should not exceed 40°C. At a temperature of 40°C, the charging current must be reduced to a value that will ensure the specified temperature.
The electrolyte temperature during charging of CH type batteries should not exceed 35°C. At temperatures above 35°C, the charge is carried out with a current that does not exceed 0.05C10, and at temperatures above 45°C - with a current of 0.025C10.
In branded batteries such as Vb VARTA, OPzS, GroE, etc. In accordance with the requirements of the specifications and technical documentation, during charging the electrolyte temperature is not allowed to rise above 55 °C.
When charging CH type batteries (as well as branded batteries that use special filters and valve-controlled linings) with a constant or gradually decreasing current, it is necessary to remove the ventilation filter plugs.
8.3. Equalizing charge.
The same charging current, even at the optimal battery charging voltage, due to the difference in self-discharge of individual batteries, may be insufficient to maintain all batteries in a fully charged state.
To bring all SK type batteries to a fully charged state and to prevent sulfation of the electrodes, it is necessary to carry out an equalizing charge with a voltage of 2.30-2.35 V/cell. until the electrolyte density in all batteries reaches a constant value of 1.20-1.21 g/cm3 at a temperature of 20 °C.
The frequency of battery equalization charges and their duration depend on the condition of the battery. An equalizing charge must be carried out at least once a year for at least 6 hours.
For those batteries where, due to the operating conditions of the electrical installation, the charging voltage can only be maintained at a level of 2.15 V per battery, an equalizing charge must be carried out quarterly.
For branded batteries, the need, frequency and conditions for equalizing charges are determined (agreed upon) in accordance with the technical documentation of the supplier companies for specific types of batteries.
When the electrolyte level drops to 20 mm above the protective shield of SN type batteries, add water and carry out an equalizing charge to completely mix the electrolyte and bring all batteries to a fully charged state.
The equalizing charge is carried out at a voltage of 2.25-2.40 V/cell. until the electrolyte density in all batteries reaches a constant value of 1.240 ± 0.005 g/cm3 at a temperature of 20°C and its level is 35-40 mm above the safety shield.
The duration of the equalizing charge is approximately:
- at a voltage of 2.25 V - 30 days;
- at a voltage of 2.40 V - 5 days.
If, when monitoring the voltage on the AE, its deviation exceeds the average value by ± 0.05 V, it is necessary to additionally monitor the density of the electrolyte in this AE (and correct it if necessary).
If the battery has single batteries with reduced voltage and reduced electrolyte density (lagging batteries), then an additional equalizing charge is carried out for them from a separate rectifier device.
8.4. Battery discharge.
Batteries that operate in constant recharge mode are practically not discharged under normal conditions. They are discharged only in the event of a malfunction or disconnection of the recharging device, in emergency conditions or during control discharges.
Individual batteries or groups of batteries are subject to discharge during repairs or troubleshooting.
For a battery on a substation, the estimated duration of emergency discharge is set to at least 1 hour. To ensure the specified duration, the discharge current should not exceed the values of 18.50 x No. A and 25 x No. A, respectively.
For branded batteries, the calculated discharge current is determined according to the technical documentation for a specific type of battery.
When discharging batteries with currents less than the 10-hour discharge mode, it is not allowed to determine the end of the discharge only by voltage. The end of the discharge is determined by the following conditions:
- reduction in electrolyte density to 1.15 g/cm3 (by 0.03-0.06 g/cm3 compared to the electrolyte density at the beginning of the discharge);
- voltage reduction to 1.80 V;
- removing the container after 10 hours.
8.5. Control digit.
Control discharges of one of the most lagging AEs or checking the performance of the AE with a jog current must be performed according to a duly approved program.
Control discharges must be performed to determine the actual capacity of the battery and carried out in a 10-hour or 3-hour discharge mode.
The discharge current value should be the same each time, but not higher than the maximum permissible for a particular type of battery.
For batteries (AE), which are used in the industry, the final voltage of control discharges is 1.80 V/cell. during discharges with 10-, 5-, three-hour discharge current and 1.75 V/el. — during discharges with one-hour and 0.5-hour discharge current.
Branded batteries allow deeper discharges at final voltages, however, in order to unify the requirements for the period of mastering and gaining operational experience, the final voltage of the 10-hour control discharge is set to 1.80 V/cell.
At the PS, control discharges are carried out if necessary. In cases where the number of batteries is insufficient to ensure the voltage on the busbars at the end of the discharge within the specified limits, it is allowed to discharge a portion of the main batteries.
Control discharges of branded batteries type Vb VARTA, OPzS, etc. are carried out in accordance with the requirements of technical documentation (TS) of supplier companies, but at least once every five years. If a trend towards a decrease in the actual capacity of the battery below the nominal is detected, control discharges can be performed every six months.
Before the control discharge, it is necessary to equalize the batteries.
The measurement results of the control discharge must be compared with the measurement results of the previous discharges. For a more correct assessment of the condition of the battery, it is necessary that all control discharges of a given battery be carried out in the same mode and entered into the battery log.
Before starting the discharge, it is necessary to record the discharge date, voltage, electrolyte density of each battery and the temperature in two or three control batteries.
During discharge on control and lagging batteries, voltage, temperature and electrolyte density should be measured in accordance with Table 9.
Table No. 9
During the last hour of discharge, the battery voltage must be measured every 15 minutes.
The test discharge must be carried out to a voltage of 1.8 V on at least one battery. For some types of branded batteries, the company’s instructions may state that the control discharge should be stopped after the final discharge voltage n x 1.8 V is reached at the terminals of the battery poles or after the corresponding time has elapsed (10 hours).
At the end of the discharge, it is necessary to take electrolyte samples from control batteries for chemical analysis and checking the content of impurities in accordance with GOST 667-73, GOST 6709-72, PUE or in accordance with the requirements of supplier companies.
After the first year of operation of batteries of type SK, SN, electrolyte analysis must be performed from all batteries.
At the end of the discharge, the voltage, temperature and density of the electrolyte, as well as the voltage between the battery poles and between the battery poles and the ground, should be measured and recorded for all AEs.
If the average temperature of the electrolyte during discharge differs from 20 °C, then the resulting actual capacity must be reduced to the capacity at a temperature of 20 °C according to the formula:
C20 = SF/1+ α(t-20), where
C20 - capacity reduced to a temperature of 20°C, A x hour;
SF - capacity actually released during discharge, A x hour;
α - temperature coefficient, in accordance with table 10;
t is the average temperature of the electrolyte during discharge, °C.
Table No. 10.
8.6. Topping up batteries.
The electrodes in the AE must always be completely recessed into the electrolyte.
The electrolyte level in SK type batteries must be maintained 10-15 mm above the top edge of the electrodes. If the electrolyte level decreases, you need to top up the batteries with distilled water, tested to be free of chlorine and iron. It is allowed to use steam condensate in accordance with GOST 6709-72. Water can be supplied to the bottom of the tank through a tube or to its upper part. In the latter case, it is recommended to recharge the battery with “boiling” to equalize the density of the electrolyte.
Batteries with an electrolyte density below 1.20 g/cm3 can be topped up with an electrolyte with a density of 1.18 g/cm3 only if the reasons for the decrease in density are identified.
The electrolyte level in SN type batteries should be between 20 and 40 mm above the safety shield. If topping up occurs when the level drops to the minimum limit, it is necessary to carry out an equalizing charge.
Under normal operating conditions, some batteries (Monolit type, SMG, etc.), especially those with valve regulation (VRLA type, etc.), do not need to be topped up with electrolyte throughout their entire service life. For some types of batteries (VARTA, etc.), refill intervals can be more than three years.
It must be borne in mind that most often, at a lower electrolyte level, the density of the electrolyte increases, so distilled water of the appropriate quality should be added (GOST 6709-72). It is necessary to add water no later than when the electrolyte level drops to the lower permissible level. In branded batteries, the electrolyte is added to a level that is 5-10 mm below the applied maximum permissible level “max”.
To achieve homogeneity of the electrolyte, it is necessary to perform an equalizing charge.
Wonderful chargers, desulfators, equalizers, and do you know that what many attribute to them out of ignorance are called in a simple word,charging algorithm. I’ve been talking about this for a long time, and yet I hear more and more wonderful devices and wonderful stories about such devices. It’s strange why, after just a month of observation, I, an ordinary engineer, express and talk about these algorithms, and it turns out they can coincide with other types of devices. That is, the algorithm of the equalizer and, for example, the charging algorithm, or the charging algorithm of an inverter with a charge equalization effect, can coincide with each other.
Attention: here I do not mean and do not say that they are identical, since in most cases it can be completed or written on the body of the MP microprogram by everyone independently from scratch. The shapes of the pulses and the timing of the pulses, and the pulse of voltage and current changes may differ and have a different time range. But often, in 50% of cases they can be similar. If not by time, then by signal shapes, if not by signal shape, but close to it.
So that each manufacturer relies on its own observations and data.
So this method itself works for the memory, the equalizer, and the inverter memory. A very useful microprogram that allows the battery to last at least 50% longer, but there is a 10% chance to increase their life.
In general, if the battery fails, many people still tell and believe in fairy tales. They buy devices like the ones described above and wait for a miracle. But, unfortunately, this device does not resurrect anything and does not restore anything. Its task is to carry out battery prevention in real time. It is precisely because of this prevention that the batteries begin to behave more stable, they do not go away, for example, when connected in series, one is overcharged and the other is not fully charged.
As they say, it is better to do prevention in time than to try to eliminate the consequences later.
Yes, I heard enough fairy tales about these miracle devices, I collected my statistics for 4 years, and finally everything came together. Of course, disassembling the device will definitely dot the I’s and the presence of a choke or watt resistances will indicate that there is buildup. But this does not mean that one battery should be discharged while charging the other, this guys is complete nonsense :)
Because the task of these devices is to equalize the voltage of the battery banks, of which there are 6 for a 12-volt battery, 10 for an alkaline battery, and accordingly twice as much for a 24-volt battery, and so on.
Honestly, at first I thought that this device was discharging a charged battery, but after looking at the results in the second year, I gave up on it. The principle is similar to a desulfator, but the algorithms are different. In general, in the future I’ll dig it up and do a full test. Nobody gave me the device and it was purchased with personal funds and this is my opinion. More information, more and more accurate data. But the fact is that they no longer coincide with the opinion of the majority - that’s for sure.
March 2016
As is known, the operation of a lead-acid battery is based on the occurrence of a potential difference between two electrodes immersed in the electrolyte. The active substance of the negative cathode is pure lead, and the active substance of the positive anode is lead dioxide. In backup and autonomous power supply systems, batteries manufactured according to different technologies: serviced bulk, sealed gel or AGM. Regardless of the technology, the chemical processes occurring in lead acid batteries, are similar:
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During operation, the so-called aging of the battery inevitably occurs, that is, a gradual loss of capacity - up to the permissible operating limit, usually taken to reduce the capacity to 60% of the original. Under ideal conditions, the actual battery life in buffer mode can be close to the nominal life. |
The aging process of a battery can be significantly accelerated due to the following destructive processes:
- Sulfation of plates;
- Corrosion of plates and shedding of active mass;
- Evaporation of the electrolyte or the so-called “drying out” of the battery;
- Electrolyte stratification (typical only for liquid batteries).
Sulfation of plates
 | When the battery is discharged, the loose active mass turns into solid microcrystals of lead sulfate. If the battery is not charged for a long time, the microcrystals become larger, the deposit thickens and blocks the access of the electrolyte to the plates, which makes charging the battery impossible. Factors that increase the risk of sulfation:
Sulfation of the plates can be partially eliminated by special battery charging modes. |
Corrosion and shedding of the active substance
 | During corrosion, pure lead of the plate grid, interacting with water, is oxidized into lead oxide. Lead oxide conducts electric current worse to the active substance of the plate lubricant, increases internal resistance and reduces the battery's resistance to high discharge currents. On the positive plates, corrosion weakens the adhesion of the grid to the active substance. In addition, the active substance of the positive plate itself gradually loses strength. With each cycle of spreading, the layer of the plate changes state from a bulk mass of microcrystals of lead oxide to a hard crystalline structure of lead sulfate. Alternating compression and expansion reduces the physical strength of the spread layer, which, combined with a weakening of adhesion, leads to sliding and shedding of the active substance to the bottom of the battery. Corrosion and accumulation of detached active substance can lead to deformation of the battery plates and, in the worst case scenario, to short circuit. |
Factors that increase the risk of corrosion and shedding of the active mass:
- charge too high voltage;
- charging with insufficient current - that is, staying under high voltage for a long time during the filling phase;
- staying in the absorption phase for too long (“overcharge”);
- charging the battery with too much current;
- accelerated battery discharge with too much current.
Shedding (sliding) of the active mass of the electrolyte is an irreversible phenomenon. The most dangerous consequence of sliding of the active mass is the shorting of the plates.
Electrolyte evaporation
 | When the positive plate of the battery is discharged, oxygen is formed from the water. Under normal float charge conditions, oxygen recombines with hydrogen on the negative plate of the battery, restoring the original amount of water in the electrolyte. But oxygen diffusion in the separator is difficult, so the recombination process cannot be 100% effective. Reducing the proportion of water changes the charging characteristics of the battery and, at a certain threshold, makes charging completely impossible. Factors that increase the risk of “battery drying out”:
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Electrolyte evaporation is an irreversible phenomenon for gel andAGM batteries. The main reason for drying out, especially forAGM – “overcharging” of batteries.
Thermal runaway and thermal breakdown of batteries
Battery aging, due to the processes listed above, occurs at an accelerated pace, but still quite slowly and often unnoticeably.
The recombination of gases in a sealed battery is a chemical process that produces heat. When recombination occurs at the correct voltage and charge current values, heating does not create problems. However, when the battery is overcharged, the internal temperature rises faster than the battery can be cooled externally. An increase in temperature reduces the charging voltage, which in the absorption stage leads to a simultaneous increase in current. This in turn increases the temperature again.
A self-sustaining cycle of increasing current and heat generation starts, leading, in the worst case scenario, to deformation of the gratings and internal short circuit with irreversible destruction of the battery.
Factors that increase the risk of thermal runaway:
- intermittent or "pulsating" charge due to unstable external source energy or poor quality charger;
- staying in the absorption phase for too long – “overcharge”;
- poor heat dissipation or elevated ambient temperature.
Specifics of destructive processes in the battery chain
 | It is easy to see that when charging a separate battery, all risk factors can be eliminated by ensuring the correct operating conditions and charging algorithm. However, power backup systems rarely use less than two batteries. With a parallel-serial connection, the charger “sees” the values of charging current and voltage only at the terminal terminals, so the voltages on individual batteries may differ significantly from the recommended values. A battery that has a higher level of self-discharge (higher leakage current) can cause overcharging of cells connected to it in series and incomplete charging of cells connected to it in parallel. Overcharging and undercharging increase the risk of almost all destructive processes. Therefore, to reduce the danger, all batteries in the chain must have the same state of charge and capacitance values as close as possible. For new installations, it is recommended to use batteries not only of the same brand, but also of the same factory batch. However, practice shows that even in one batch There are not even two batteries with exactly the same characteristics capacity, state of charge and internal leakage currents. Moreover, the requirement of identical characteristics is unattainable when it is necessary to replace a damaged battery in an already used battery. |
A slight variation in the degree of charge of new batteries is most often smoothed out during the running-in process over several discharge and charge cycles. But if there is a significant scatter or difference in capacity characteristics imbalancebetween individual batteries of the array only increases over time.
Systematic recharging of batteries with a lower capacity and possible reversal of the polarity of undercharged batteries during deep discharges lead to the accumulation of damage and failure of individual batteries. Due to the thermal runaway effect, even one failed battery can destroy the entire battery array.
Active battery equalization
You can smooth out differences in battery parameters using a special device called a battery charge balancer or imbalance leveler.
IMPORTANT! The use of charge balancers reduces the risk of destructive processes, but cannot fix an already seriously damaged battery.
Physically, the battery charge equalization device is a compact electronic module connected to each pair of series-connected elements:
- for 24V battery required one charge balancer to the chain (scheme 1).
- for a 48V battery required three charge balancers to the chain (Scheme 2).
The SBB is powered from the battery itself or from a charge source. SBB's own power consumption is low and comparable to self-discharge losses.
Level efficiency SBB2-12-A fundamentally higher than that of other charge balancers, the operation of which is based either on shunting excess charging power (so-called passive balancers, creating direct energy losses), or on selective recharging of elements (equalization occurs only during charging). Maximum equalization current SBB2-12-A– 5A, which exceeds the capabilities of all alternative devices on the market.
The effect of using a charge balancer:
1) Improved overall reliability and increasing battery life.
2) Increased energy output battery, because When batteries are deeply discharged, the capacity of all batteries in a series circuit is more fully used.
SBB balancers work continuously, keeping the batteries in a balanced state even when the charger is turned off.
Connection diagram
Connection diagram for a level (balancer) to a 24V and 48V battery.
Below are the charge level connection diagrams SBB2-12-A to lead-acid rechargeable batteries 12V in batteries rated 24V and 48V.
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Scheme 1. 24V battery from two 12V batteries | Scheme2. 48V battery from four 12V batteries |
Connecting a level (balancer) to a battery of several parallel circuits.
It is allowed to operate one charge equalization balancer SBB on 2-3 parallel chains of batteries - if the imbalance is small and the maximum equalization current is not exceeded. Separate balancing of each chain gives top scores due to the selectivity of the corrective action.
When using one level for several chains, it is necessary to use a diagram for connecting batteries with DC buses and connecting midpoints (Scheme 3).
When using a separate level in each chain, you can use the usual battery connection diagram (Scheme 4).
- Carry out an external inspection of the battery. The top surface of the battery and terminal connections must be clean and dry, free from dirt and corrosion.
- If there is liquid on the top surface/of the flooded batteries, this may indicate that there is too much liquid in the battery. If there is liquid on the surface of a GEL or AGM battery, the battery is overcharged and its performance and life will be reduced.
- Check battery cables and connections. Replace damaged cables. Tighten loose connections.
Cleaning
- Make sure all protective caps are securely attached to the battery.
- Clean the top surface of the battery, terminals and connections using a rag or brush and a solution of baking soda and water. Do not allow cleaning solution to get inside the battery.
- Rinse with water and dry with a clean cloth.
- Apply a thin layer of petroleum jelly or terminal protectant, available from your local battery supplier.
- Keep the area around batteries clean and dry.
Adding water (ONLY batteries with liquid electrolyte)
It is forbidden to add water to gel or AGM batteries, since they do not lose it during operation. Water needs to be added periodically to flooded batteries. The frequency of topping up depends on the nature of battery use and operating temperature. New batteries should be checked every few weeks to determine the frequency of topping up water for a specific application. Batteries typically require more frequent toppings as they age.
- Fully charge the battery before adding water. Add water to discharged or partially charged batteries only if the plates are visible. In this case, add just enough water to cover the plates, then charge the battery and continue the water refill process described below.
- Remove the protective caps and turn them over to prevent dirt from getting on the inside surface. Check the electrolyte level.
- If the electrolyte level is significantly higher than the plates, then it is not necessary to add water.
- If the electrolyte level barely covers the plates, add distilled or deionized water to a level 3 mm below the ventilation well.
- After adding water, install the protective caps back on the battery.
- Tap water can be used if the level of contamination is within acceptable limits.
Charge and equalization charge
Charge
Proper charging is extremely important to get the most out of your battery. Both undercharging and overcharging a battery can significantly shorten its service life. For proper charging, see the instructions included with the equipment. Most chargers are automatic and pre-programmed. Some chargers allow the user to set the voltage and current values. See charging recommendations in the Table.
- Make sure the charger is set to the correct program for wet, gel or AGM batteries, depending on the type of battery you are using.
- The battery must be fully charged after each use.
- Lead-acid batteries (wet, gel and AGM) do not have a memory effect and therefore do not require a complete discharge before recharging.
- Charging should only be carried out in well-ventilated areas.
- Before charging, check the electrolyte level to ensure that the plates are covered with water (wet batteries only).
- Before charging, make sure that all protective caps are securely attached to the battery.
- Batteries with liquid electrolyte will release gas (bubbles) before completing the charging process to ensure the electrolyte is properly mixed.
- Do not charge a frozen battery.
- Charging should be avoided at temperatures above 49°C.
Scheme 4
Scheme 4 and 5
Equalizing charge (ONLY for wet batteries)
An equalization charge is a battery overcharge performed on wet batteries after they have been fully charged. Trojan recommends performing an equalization charge only when batteries have a low specific gravity, less than 1.250, or a specific gravity that fluctuates within a wide range, 0.030, after the battery is fully charged. Do not equalize charge GEL or AGM batteries.
- You must make sure that the battery is a wet battery.
- Before starting charging, check the electrolyte level and make sure that the plates are covered with water.
- Make sure that all protective caps are firmly attached to the battery.
- Set the charger to equalizing charge mode.
- During the equalizing charge process, gas will be released in the batteries (bubbles will float to the surface).
- Measure the specific gravity every hour. The equalizing charge should be stopped when the specific gravity stops increasing.
ATTENTION! It is prohibited to perform an equalization charge on gel or AGM batteries.
The same charge current, even at the optimal battery charge voltage, may not be sufficient to maintain all battery cells in a fully charged state. This is due to differences in the self-discharge of individual elements.
To bring all battery cells into a fully charged state and to prevent sulfation of the electrodes, it is necessary to carry out equalizing charges with a voltage of 2.30-2.35 V per cell until a steady-state electrolyte density in all cells of 1.20-1.21 g/cm3 is achieved at a temperature of 20 °C. The equalizing charge is carried out according to the program. The equalizing charge of the battery must be carried out by the employee responsible for operating the battery.
For branded batteries, the need, frequency and conditions for performing equalizing charges are determined in accordance with the technical documentation of the suppliers or manufacturers.
The frequency of equalizing charges and their duration depend on the condition of the battery and should be at least once a year with a duration of at least 6 hours. On those batteries where, due to the operating conditions of the electrical installation, the charging voltage can only be maintained at a level of 2.15 V per cell, equalization charges must be carried out quarterly
If during monitoring the voltage deviation on the AE exceeds the average value by ±0.05 V, then it is necessary to additionally monitor the density of the electrolyte in this element (and, if necessary, correct it). If the AB contains single elements with reduced voltage and reduced electrolyte density (lagging batteries), then they require an additional equalizing charge from a separate rectifier device.
The equalizing charge is carried out without taking the battery out of operation. Charger is switched on according to the charging circuit for all elements (main and end). The rated voltage on the DC buses is maintained by switching the control buses to the position of the 100th element. To equalize the charge current, it is necessary to connect an additional discharge resistor between 100m and the last element (RN1).
If the battery has additional elements, then it is necessary to connect an additional discharge resistance in parallel with these elements (Rн2). It is possible to use one adjustable resistance, in normal mode connected between 108-120 el., which during equalizing charge is connected to 100 - 120 el.
AB control digit
The control discharge of the battery at the substation is carried out in order to determine its actual capacity with a current of 10 or 3 hour discharge mode. The decision to conduct a control discharge is made after analyzing its condition and performance based on the results of inspections, inrush current testing, the presence of a significant number of lagging elements, and the presence of unclear reasons for failures to turn on oil switches. The control discharge is performed by the person responsible for the operation of the battery, subject to an authorized application and in accordance with the program approved by the chief engineer of the MES.
Before the control discharge of the battery, it is necessary to make an equalizing charge of the battery. Before starting the discharge, it is necessary to record the discharge date, voltage, electrolyte density of each AE and temperature in the control elements.
The depth of discharge must be strictly controlled by two parameters: voltage and electrolyte density. If the control discharge is carried out with a current of 3 or 10 hour discharge mode, then in this case the discharge should stop when at least one element reaches a voltage of 1.8 V. When discharging with low currents, the discharge should stop:
· when the voltage drops to 1.8 V on at least one element;
· when the electrolyte density decreases to a value c = 1.15 g/cm3 (by 0.03 h 0.05 g/cm3 compared to the initial density at the beginning of the discharge)
· when removing the nominal capacity of the 10-hour discharge mode.
When discharging, it is not allowed to take away from the battery a capacity greater than that guaranteed for a given discharge mode. During the discharge on control and lagging AEs, the temperature and density of the electrolyte should be measured in accordance with Table No. 2.
Table No. 2 Scope of required measurements when discharging batteries
At the end of the discharge, it is necessary to measure and record the voltage, temperature and density of the electrolyte on all battery elements, as well as the voltage between the poles of the battery and between each pole and the ground. Take electrolyte samples from control cells for chemical analysis and checking the content of impurities in the electrolyte. After the first year of operation, electrolyte analysis must be performed on all battery cells.
The value of the discharge current must be the same each time. The results of measurements during control discharges must be compared with the measurement results of previous discharges. Their values should not differ by more than 10%.
If during the test discharge it turns out that the battery capacity differs significantly from the nominal one, it is necessary to check the capacity of the electrodes using a cadmium electrode and, depending on the test results, outline measures to restore the battery capacity.