Traction lead-acid batteries (AB) with tubular positive plates are designed to ensure continuous operation of electric vehicles - electric forklifts, stackers, trolleys, scrubber dryers, as well as mine tractors, electric locomotives, trams and trolleybuses.
Basic battery parameters
The main parameters of the battery are rated voltage, rated capacity, overall dimensions and service life.
Rated voltage one battery cell is 2 V, respectively, the total rated voltage of a battery consisting of N batteries connected in series is equal to the sum of the voltages of each of them. For example, the voltage of a battery consisting of 24 cells is 48 V. The normal voltage value during proper operation can vary during operation from 1.86 to 2.65 V/cell for batteries with liquid electrolyte and from 1.93 to 2.65 V /cell for gel batteries.
Historical reference
The idea to thicken the battery electrolyte to a gel state came from Dr. Jacobi, a developer of the Sonnenschein company, in 1957. In the same year, the dryfit technology was patented and the production of gel batteries began. Interestingly, their first analogues began to appear on the market only in the mid-1980s, at which time Sonnenschein already had almost 30 years of experience in the production of such batteries.
Electrical capacity The battery is the amount of electricity removed when the battery is discharged. Capacity can be measured in different modes, for example, with a 5-hour discharge (C 5) and a 20-hour discharge (C 20). In this case, the same battery will have a different capacity value. So, with a battery capacity C 5 = 200 Ah, the capacity C 20 of the same battery will be equal to 240 Ah. This is sometimes used to inflate battery capacity. As a rule, the capacity of traction batteries is measured in a 5-hour discharge mode, stationary batteries - in a 10-hour or 20-hour discharge mode, and starter batteries - only in a 5-hour discharge mode. In addition, as the temperature of the battery decreases, its usable capacity decreases.
Dimensions, As a rule, they are of decisive importance, since in any electric-powered equipment a special seat is provided for the battery. The exact size of the box can often be determined by the model of the machine.
Life time The battery (for leading Western European manufacturers) is defined by DIN/EN 60254-1, IEC 254-1 and is 1500 cycles for batteries with liquid electrolyte and 1200 cycles for gel batteries. However, the actual service life may differ greatly from these figures, and, as a rule, to a lesser extent. It depends primarily on the quality of production and materials used, on correct operation and timely maintenance, on the mode of operation, as well as the type of charger used.
Exploitation
Conventionally, operation and maintenance procedures can be divided into four groups - daily, weekly, monthly and annual operations.
Daily Operations:
- charge the battery after discharge;
- Check the electrolyte level and, if necessary, adjust it by adding distilled water.
Weekly Operations:
- clean the battery from dirt;
- conduct a visual inspection;
- Carry out an equalizing charge (optional).
Monthly transactions:
- check the serviceability of the charger;
- check and record in the log the value of electrolyte density on all cells (after charging);
- check and record in the log the voltage value on all elements (after charging).
Annual transactions:
- measure the insulation resistance between the battery and the machine body. The insulation resistance of traction batteries in accordance with DIN VDE 0510, part 3 must be at least 50 Ohms for each volt of rated voltage.
Generally speaking, adding water is required approximately once every 7 cycles (once a week for single-shift operation), but a check is required after each charge, since water is consumed unevenly.
On a note
When replacing alkaline batteries with lead-acid ones, you must keep in mind that these batteries cannot be charged together, so you need to either immediately convert the entire fleet of batteries to lead-acid ones, or use two isolated charging rooms. In addition, when replacing alkaline batteries with lead-acid ones, you will need to change the charger.
Electrolyte
The electrolyte plays a key role in traction batteries. It is filled once, during commissioning, and the stability of the battery throughout its service life depends on its quality (which is why it is better to purchase batteries that have been filled and charged at the factory). When using a battery during charging, as a result of electrolysis, water decomposes into oxygen and hydrogen (visually this looks like boiling electrolyte), which is why it is necessary to periodically add water. The electrolyte level is usually determined by the min and max marks on the filler plug. In addition, there is an Aquamatic automatic water topping system, which significantly speeds up this process.
Golden rules
When using batteries, the following basic rules must be observed:
Never leave the battery in a discharged state. After each discharge, the battery must be recharged immediately, otherwise the irreversible process of sulfation of the plates will begin. This results in reduced battery capacity and service life.
Discharge the battery no more than 80% (for gel batteries - 60%). As a rule, this is the responsibility of the discharge sensor installed on the machine, but its breakdown, absence or incorrect setting can also lead to sulfation of the plates, overheating of the batteries during charging and ultimately a reduction in their service life.
Only distilled water can be added to the battery. Ordinary water contains many impurities that have a negative effect on the battery. Adding electrolyte to the battery to increase density is prohibited: firstly, this will not increase the capacity, and secondly, it will cause irreversible corrosion of the plates.
On a note
The temperature of the battery electrolyte should not fall below +10 °C before charging, but this does not prohibit operation in areas with low temperatures down to –40 °C. In this case, you need to give the battery enough time to warm up before charging. During charging, the battery heats up by approximately 10 °C.
Since the battery's usable capacity decreases as the battery temperature drops, conventional chargers based on the Wa or WoWa charging method will undercharge the battery.
For charging, it is recommended to use “smart” devices that monitor the state of the battery during the charging process, preventing undercharging or overcharging, for example, Tecnys R, or use thermal compensation - adjusting the charging current depending on the temperature of the battery.
Battery cleaning
Cleanliness is absolutely essential not only to keep the battery looking good, but even more so to prevent accidents and damage, reduce battery life, and keep the battery in a usable condition. Battery cases, boxes, insulators must be cleaned to ensure the required insulation of the elements in relation to one another, in relation to ground (“ground”) or external conductive parts. In addition, cleaning avoids corrosion damage and stray currents. Regardless of the operating time and location, dust inevitably settles on the battery.
A small amount of electrolyte protruding from the battery during charging after the gas generation voltage is reached forms a more or less conductive layer on the covers of cells or blocks, through which stray currents flow. The result is increased and non-uniform self-discharge of elements or blocks. This is one of the reasons why electric machine operators complain about decreased battery capacity after the machine has been left idle for a weekend.
There is an opinion that maintenance-free systems are possible only on the basis of gel batteries, the use of which entails natural limitations (long charging time, reduced capacity and high cost). However, few people know that maintenance-free and ultra-low-maintenance systems are also possible using batteries with liquid electrolyte (for example, Liberator batteries).
Battery log and work organization
When using a fleet of electric forklifts, it is advisable to assign its own batteries to each forklift. To do this, they are numbered: 1a, 1b, 2a, 2b, etc. (batteries with the same number are used on the same loader). After this, a journal is started in which information is reflected daily about each battery, illustrated with an example.
| Battery number | Installed on a loader | Charged | ||||||
|---|---|---|---|---|---|---|---|---|
| date | Time | Meter readings, machine-hours | date | Time | Density (average of three elements selected) | Meter readings, machine-hours | ||
| 1a | ||||||||
| 1b | ||||||||
| 2a | ||||||||
| etc. | ||||||||
Thus, with the help of this measure, you can avoid the use of undercharged batteries, as well as predict and plan the replacement of the battery before it completely fails. In addition, it is advisable to keep another log for each battery, which once a month reflects the information about the battery listed in example 2. This data is the main source of information for the service department, so often maintaining such a log is a prerequisite for warranty service. One or two (in the case of two-shift work) people should be responsible for the entire battery system. Their responsibilities in this area of responsibility should include receiving and issuing batteries, their maintenance and charging, maintaining battery logs, and predicting battery failure.
Stationary acid batteries at substations and in production workshops of industrial and other enterprises must be installed in accordance with the requirements of the PUE. Install acid and alkaline batteries in the same room prohibited.
Walls, ceilings, doors, window frames, metal structures, shelving and other parts of the room intended for the installation of acid batteries must be painted with acid-resistant paint. Ventilation ducts must be painted on the outside and inside.
To illuminate such premises, lamps installed in explosion-proof fittings are used. Switches, sockets and fuses must be located outside the battery room. Lighting wiring is carried out with a wire in an acid-resistant sheath.
The voltage on the operational DC buses under normal operating conditions is maintained 5% higher than the rated voltage of the pantographs.
The battery installation must be equipped with: circuit diagrams and electrical wiring diagrams; densimeters (hydrometers) and thermometers for measuring the density and temperature of the electrolyte; portable DC voltmeter with measurement limits of 0-3 V; portable sealed lamp with safety net or battery-powered flashlight; a mug made of chemically resistant material with a spout (or jug) with a capacity of 1.5-2 liters for preparing electrolyte and adding it to vessels; safety glasses for covering elements; acid-resistant suit, rubber apron, rubber gloves and boots, safety glasses; a solution of soda for acid batteries and boric acid or vinegar essence for alkaline batteries; portable jumper for bridging battery cells.
For installations without permanent operating personnel, it is allowed to have all of the above in the supplied kit.
When accepting a newly installed or overhauled battery, the following is checked: availability of documents for installation or major repair of the battery (technical report); battery capacity (current 3-5 A or 10-hour discharge mode); electrolyte quality; electrolyte density and cell voltage at the end of battery charge and discharge; battery insulation resistance relative to ground; serviceability of individual elements; serviceability of supply and exhaust ventilation; compliance of the construction part of the battery premises with the requirements of the PUE.
Acid batteries operating using the constant recharging or “charge-discharge” methods are subjected to an equalizing charge (recharge) once every 3 months with a voltage of 2.3-2.35 V per cell until a steady-state electrolyte density in all cells is 1.2- 1.21 g/cm3. The duration of recharging depends on the condition of the battery, but not less than 6 hours.
The battery can be charged and discharged with a current no higher than the maximum guaranteed for this battery. The electrolyte temperature at the end of the charge should not exceed +40 °C. During equalization charge, the battery must be given at least three times its rated capacity. In addition, at substations, once every 3 months the performance of the batteries is checked by the voltage drop when the current is turned on for a short time.
The supply and exhaust ventilation of the room is turned on before charging the battery and is turned off after complete removal of gases no earlier than 1.5 hours after the end of charging, and when working using the constant recharging method - as necessary in accordance with local instructions.
Measurements of voltage, density and temperature of the electrolyte of each element of stationary batteries are performed at least once a month.
When the voltage across the acid battery cells drops to 1.8 V, the discharge of the battery is stopped and the battery is charged. You cannot leave the battery discharged for more than 12 hours, as this reduces the battery capacity.
When starting to charge the battery, first turn on the supply and exhaust ventilation of the room and check its operation, then connect the battery to the charging unit, observing the polarity of the poles. The charging current value at the beginning of the battery charging process is taken from the tables recommended in the manufacturer's instructions (approximately 20% more than the nominal charging current value). In this mode, charging continues until the battery voltage reaches 2.4 V. Then the charging current is halved, and the charging process continues until it is completed. Charging is considered complete if the voltage across the cells reaches 2.6-2.8 V and does not increase any further, and the electrolyte density of 1.20-1.21 g/cm3 does not change within an hour. At this time, “boiling” of the electrolyte of both polarities is observed.
When charging an acid battery, the temperature of the electrolyte is monitored. When +40 °C is reached, the charge is stopped and the electrolyte is allowed to cool to +30 °C. At the same time, the density of the electrolyte and the voltage at the terminals of individual cells are measured. The high temperature of the electrolyte accelerates the wear of the cells and increases their self-discharge. Low temperature increases the viscosity of the electrolyte, which worsens the discharge process and reduces the capacity of the cells. Therefore, the temperature in the battery cells is maintained at a level of at least +10. When charging, it may turn out that individual elements of the acid battery are not fully charged; Such elements must be recharged separately.
A lead acid battery should not be discharged to a deep discharge level, which causes sulfation. During sulfation, solid masses of lead sulfate are formed on the plates of a lead battery, which clog the pores in the plates. In this regard, the passage of electrolyte is difficult, which prevents the battery from being restored under normal charge conditions. During normal discharge, fine-grained lead sulfate is formed on the plates, which does not interfere with the subsequent recovery of the batteries when charging. The electrolyte density at the end of the charge reaches 1.15–1.17 g/cm3.
The density of the electrolyte is measured using a densimeter (ariometer). During operation, the electrolyte level gradually decreases and is topped up from time to time.
The duty personnel systematically monitor the operating conditions of the acid battery (all data on current, voltage, electrolyte density, temperature are recorded in protocols in accordance with the factory instructions).
Battery Inspection carried out: by staff on duty - once a day; foreman or substation manager - 2 times a month; at substations without permanent duty personnel - by operating personnel simultaneously with the inspection of equipment, as well as by a specially designated person - according to a schedule approved by the chief power engineer of the enterprise.
To increase the service life of acid batteries, they are operated in a constant recharge mode (connecting a charged battery in parallel with a charger). This is due to the fact that when an acid battery operates using the charge-discharge method (supplying the load with a charged battery and then charging it after discharging), the wear of the positive plates of the batteries occurs much faster than in the constant recharge mode.
The advantage of trickle charge mode is that the battery plate is always in a state of full charge and can provide normal power to the load at any time.
When using acid batteries, not all batteries have the same self-discharge. The reason for this may be uneven temperature conditions (different distances from heating devices), as well as different degrees of contamination of the electrolyte in the batteries. Batteries with high self-discharge (lagging) are subject to deeper sulfation. Therefore, acid batteries are subjected to an equalizing charge once every 3 months.
Maintenance battery inspection is carried out according to the PPTOR system, but at least once a year.
During routine repairs of a battery, the following is carried out: checking the condition of the plates and replacing them in individual elements (if necessary); replacement of part of the separators; removing sludge from elements; checking the quality of the electrolyte; checking the condition of the racks and their insulation relative to the ground; troubleshooting other battery problems; inspection and repair of the building part of the premises.
All work when operating acid batteries during operations with acid and electrolyte is carried out in rubber boots, an apron, gloves and woolen overalls. Safety glasses are required to protect your eyes. There should always be a 5% solution of baking soda near the workplace to wash skin areas affected by acid or electrolyte.
Major renovation batteries are carried out according to the PPTOR system, but at least once every 3 years.
Invented by French physicist Raymond Louis Gaston Plante in 1859, the lead-acid battery was the first battery for commercial use. Today, flooded lead-acid batteries are widely used in cars, electric forklifts, and uninterruptible power supplies (UPS).
Flooded lead-acid batteries consist of lead plates that act as electrodes, immersed in water and sulfuric acid. These batteries require some maintenance due to loss of hydrogen over time.
In the mid-1970s, researchers developed maintenance-free lead-acid batteries that could operate in any position in space. The liquid electrolyte was replaced by wetted separators and the insulation problem was solved. Safety valves were added to allow air to be removed during charging and discharging. However, maintenance-free batteries are more expensive and have a shorter lifespan than flooded batteries.
Lead-acid batteries may have liquid or gel electrolyte.
Depending on the application, two designations for lead-acid batteries have emerged. These are small sealed lead acid (SLA, sealed lead acid) batteries and big valve adjustable lead-acid (VRLA, valve regulated lead acid) batteries. Structurally, both batteries are the same. (Some might argue that the title " sealed lead acid battery" is incorrect because a lead-acid battery cannot be completely sealed. I agree - this is true, the name is not entirely correct, but this does not prevent it from being widespread). I will focus on portable batteries, so I will focus on SLA.
Unlike a flooded lead acid battery like SLA, so VRLA have a low overvoltage potential to prevent gas evolution during charging. Overcharging causes gas formation and dehydration of the battery. Consequently, these batteries cannot be charged to their full potential.
Lead-acid batteries do not have a memory effect. Leaving the battery on charge for a long time will not damage it. The charge retention time of a lead-acid battery is the best among various types of batteries. While a nickel-cadmium battery will self-discharge to about 40 percent of its stored energy in three months, SLA self-discharges by the same amount within one year. SLA are relatively inexpensive sources of energy.
SLA cannot be quickly charged - a typical charge cycle lasts 8-16 hours.
SLA must always be kept charged. Leaving the battery in a discharged state will trigger a process called sulfation(essentially, this is oxidation and crystallization), which can make it impossible to recharge it later.
Unlike nickel-cadmium batteries, SLA does not like deep discharge. A full discharge causes additional strain, and each cycle robs the battery of a small amount of power. This declining wear pattern also applies to other chemical batteries to varying degrees. In order to prevent frequent deep battery discharges, it is better to use SLA slightly larger than the required capacity.
Depending on the depth of discharge and operating temperature, SLA provides from 200 to 300 charge/discharge cycles. The main reason for this relatively short life cycle is corrosion of the positive electrode grid, depletion of the active material and expansion of the positive plates. These changes are more pronounced at higher operating temperatures.
Optimal operating temperature for batteries SLA And VRLA, is a temperature of 25°C. Typically, an 8°C increase in temperature will reduce battery life by half. VRLA, working for 10 years at 25°C will work only 5 years at 33°C, and just over a year at 42°C.
Among modern rechargeable batteries, the lead-acid battery family has the lowest energy density, measured in Watts/kg, making it unsuitable for portable devices that require a compact power source. In addition, the efficiency of such batteries at low temperatures leaves much to be desired.
Lead-acid batteries perform well at high pulse currents. Full power can be supplied to the load in a short time. This makes them ideal for use where large amounts of power may suddenly be needed. This is why they are used to electrically start internal combustion engines in most vehicles.
From a recycling point of view, SLA is less harmful than nickel-cadmium batteries, but the high lead content makes SLA non-ecological.
Advantages of lead-acid batteries
- Inexpensive and easy to manufacture - in terms of cost per Wh, SLA is the least expensive. For example, a 12V battery with a capacity of 3.2 Ah, measuring 134x67x60mm, costs about 400 rubles.
- Mature, reliable and well-developed technology - when used correctly, SL A are quite durable
- Low self-discharge - self-discharge rate is one of the lowest in battery systems (3-20% per month)
- Low maintenance requirements - no memory effect, no need to top up electrolyte
- Capable of high current output. For the battery mentioned above with C = 3.2 Ah, the current output is at least 16A. The battery delivers a large starting current to the load without draining the supply voltage.
Disadvantages of lead-acid batteries
- Cannot be stored in a discharged state
- High sensitivity to temperature changes - affects both operating time and battery life
- Low energy density - the low weight-energy density of the battery limits the scope of application to stationary and wheeled applications, so it is advisable to use them only in large and medium-sized robots (if we talk about robots)
- Allows only a limited number of complete discharge cycles—well suited for backup applications where only occasional deep discharges occur
- Environmentally harmful - electrolyte and lead content make them unsafe for the environment
- Transport restrictions for flooded lead acid batteries - acid may leak in case of accident
Typical characteristics of lead-acid batteries
I will give typical parameter values found for maintenance-free 6 and 12 volt batteries with a capacity of about 0.8-7 Ah:
- Theoretical energy content: 135 Wh/kg
- Specific energy intensity: 30-60 Wh/kg
- Specific energy density: 1250 Wh/dm 3
- EMF of a charged battery: 2.11V
- Operating voltage: 2.1V (3 or 6 sections give standard 6.3 or 12.6V)
- Voltage of a completely discharged battery: 1.75-1.8V (per section). Lower charge is not allowed
| Voltage | Charge |
| 12.70V | 100% |
| 12.46V | 80% |
| 12.24V | 55% |
| 12.00V | 25% |
| 11.90V | 0% |
- Operating temperature: from -40 to +40ºС
- Efficiency: 80-90%
The article discusses the use and operation of lead-acid sealed batteries, which are most widely used for redundancy of fire alarm equipment (FS).
Sealed lead-acid batteries (hereinafter referred to as batteries), which appeared on the Russian market in the early 90s, intended for use as direct current sources for power supply or backup of security, communications and video surveillance equipment, quickly gained popularity among users and developers . The most widely used batteries are those produced by the following companies: Power Sonic, CSB, Fiamm, Sonnenschein, Cobe, Yuasa, Panasonic, Vision.
Batteries of this type have the following advantages:
Figure 1 - Dependence of battery discharge time on discharge current
- tightness, absence of harmful emissions into the atmosphere;
- no need to replace electrolyte or add water;
- Possibility of operation in any position;
- does not cause corrosion of fire alarm equipment;
- resistance without damage to deep discharge;
- low self-discharge (less than 0.1%) of the nominal capacity per day at an ambient temperature of plus 20 °C;
- maintaining operability for more than 1000 cycles of 30% discharge and over 200 cycles of full discharge;
- possibility of storing in a charged state without recharging for two years at an ambient temperature of plus 20 °C;
- the ability to quickly restore capacity (up to 70% in two hours) when charging a completely discharged battery;
- ease of charging;
- When handling the products, no precautions are required (since the electrolyte is in the form of a gel, there is no acid leakage if the case is damaged).
Figure 2 - Dependence of battery capacity on ambient temperature
One of the main characteristics is the battery capacity C (the product of the discharge current A and the discharge time h). The nominal capacity (the value indicated on the battery) is equal to the capacity that the battery provides when discharged for 20 hours to a voltage of 1.75 V on each cell. For a 12-volt battery containing six cells, this voltage is 10.5 V. For example, a battery with a nominal capacity of 7 Ah provides operation for 20 hours at a discharge current of 0.35 A. When calculating the battery operating time at a discharge current different from 20-hour, its actual capacity will differ from the nominal one. So, with a discharge current of more than 20 hours, the actual battery capacity will be less than the nominal ( picture 1).
The battery capacity also depends on the ambient temperature ( figure 2).
All manufacturing companies produce batteries of two ratings: 6 and 12 V with a nominal capacity of 1.2 ... 65.0 Ah.
BATTERY OPERATION
When using batteries, you must comply with the requirements for their discharge, charging and storage.
1. Low battery
When the battery is discharged, the ambient temperature must be maintained within the range from minus 20 (for some types of batteries from minus 30 °C) to plus 50 °C. Such a wide temperature range allows batteries to be installed in unheated rooms without additional heating.
It is not recommended to subject the battery to a “deep” discharge, as this may lead to its damage. IN table 1 The values of the permissible discharge voltage are given for various values of the discharge current.
Table 1
The battery should be charged immediately after discharge. This is especially true for a battery that has been “deeply” discharged. If the battery remains in a discharged state for a long period of time, a situation may arise in which it will be impossible to restore its full capacity.
Some developers of power supplies with a built-in battery set the battery shutdown voltage when it is discharged extremely low (9.5 ... 10.0 V), trying to increase the operating time in reserve. In fact, the increase in the duration of its work in this case is insignificant. For example, the residual capacity of a battery when discharged with a current of 0.05 C to 11 V is 10% of the nominal, and when discharged with a high current this value decreases.
2. Connecting multiple batteries
To obtain voltage ratings above 12 V (for example, 24 V), used to back up control panels and detectors for open areas, it is possible to connect several batteries in series. In this case, the following rules must be observed:
- It is necessary to use the same type of batteries produced by the same manufacturer.
- It is not recommended to connect batteries with a manufacturing date difference of more than 1 month.
- It is necessary to maintain the temperature difference between batteries within 3 °C.
- It is recommended to maintain the required distance (10 mm) between batteries.
3. Storage
Figure 3 - Dependence of changes in battery capacity on storage time at different temperatures It is allowed to store batteries at ambient temperatures from minus 20 to plus 40 °C.
Batteries supplied by manufacturers in a fully charged state have a fairly low self-discharge current, however, during long-term storage or using a cyclic charging mode, their capacity may decrease ( figure 3). When storing batteries, it is recommended to recharge them at least once every 6 months.
4. Battery charge
Figure 4 - Dependence of battery life on ambient temperature
The battery can be charged at ambient temperatures from 0 to plus 40 °C.
When charging a battery, do not place it in a hermetically sealed container, as gases may be released (when charging with a high current).
CHARGER SELECTION
Figure 5 - Dependence of changes in the relative capacity of the battery on the service life in buffer charging mode
The need to choose the right charger is dictated by the fact that excessive charging will not only reduce the amount of electrolyte, but will lead to rapid failure of the battery cells. At the same time, reducing the charge current leads to an increase in charge duration. This is not always desirable, especially when reserving fire alarm equipment at facilities where power outages often occur,
Battery life varies greatly depending on charging methods and ambient temperature ( pictures 4, 5, 6).
Buffer charge mode
Figure 6 - Dependence of the number of battery discharge cycles on the discharge depth * % shows the discharge depth for each cycle of the nominal capacity, taken as 100%
In buffer charging mode, the battery is always connected to a DC source. At the beginning of the charge, the source works as a current limiter, at the end (when the voltage on the battery reaches the required value) it begins to work as a voltage limiter. From this moment, the charge current begins to fall and reaches a value that compensates for the self-discharge of the battery.
Cyclic charge mode
Cyclic charging mode charges the battery and then disconnects it from the charger. The next charge cycle is carried out only after the battery is discharged or after a certain time to compensate for self-discharge. Battery charge characteristics are given in table 2.
table 2
Note - The temperature coefficient should not be taken into account if the charge occurs at an ambient temperature of 10 ... 30 ° C.
On Figure 6 shows the number of discharge cycles that the battery can be subjected to depending on the depth of discharge.
Accelerated battery charging
Accelerated charging of the battery is allowed (only for cyclic charging mode). This mode is characterized by the presence of temperature compensation circuits and built-in temperature protective devices, since when a large charging current flows, the battery may heat up. The characteristics of accelerated battery charging are given in table 3.
Table 3
Note - A timer should be used to prevent the battery from charging.
For batteries with a capacity of more than 10 Ah, the initial current should not exceed 1C.
The service life of sealed lead-acid batteries can be 4...6 years (subject to the requirements for charging, storage and operation of batteries). Moreover, during the specified period of their operation no additional maintenance is required.
* All drawings and technical specifications used in this article are given from the documentation for Fiamm batteries, and also fully correspond to the technical characteristics of the battery parameters produced by Cobe and Yuasa.
Continue reading
What battery capacity do you need? When calculating an autonomous power supply system, it is very important to choose the correct battery capacity. The specialists of the “Your Solar Home” company will help you correctly calculate the required battery capacity for your energy system. For preliminary calculations, you can use the following simple...
All batteries have an expiration date, and with numerous charge-discharge cycles and many hours of use, the battery loses its capacity and holds a charge less and less.
Over time, the battery capacity drops so much that its further use becomes impossible.
Probably many people have already accumulated batteries from uninterruptible power supplies (UPS), alarm systems and emergency lighting.
Many household and office equipment contain lead-acid batteries, and regardless of the brand of battery and manufacturing technology, whether it is a regular serviceable car battery, AGM, gel-lium (GEL) or a small flashlight battery, they all have lead plates and an acid electrolyte.
At the end of their service, such batteries cannot be thrown away because they contain lead; basically, they are destined for recycling where the lead is extracted and processed.
But still, despite the fact that such batteries are basically “maintenance-free”, you can try to restore them by returning them to their previous capacity and use them for some more time.
In this article I will talk about how restore 12 volt battery from UPSa to 7ah, but the method is suitable for any acid battery. But I want to warn you that these measures should not be carried out on a fully working battery, since on a working battery, capacity can only be restored using the correct charging method.
So we take the battery, in this case old and discharged, and pry off the plastic cover with a screwdriver. Most likely it is point-glued to the body.
Lifting the lid we see six rubber caps, their task is not to service the battery, but to bleed off gases formed during charging and operation, but we will use them for our purposes.
We remove the caps and pour 3 ml of distilled water into each hole using a syringe; it should be noted that other water is not suitable for this. And distilled water can be easily found in a pharmacy or at a car market; in extreme cases, snow melt water or clean rainwater may be suitable.
After we have added water, we put the battery on charge and we will charge it using a laboratory (regulated) power supply.
We select the voltage until some charging current values appear. If the battery is in poor condition, then the charging current may not be observed, at first, at all.
The voltage must be increased until a charging current of at least 10-20 mA appears. Having achieved such charging current values, you need to be careful, since the current will increase over time and you will have to constantly reduce the voltage.
When the current reaches 100mA, there is no need to reduce the voltage any further. And when the charging current reaches 200mA, you need to disconnect the battery for 12 hours.
Then we connect the battery again for charging, the voltage should be such that the charging current for our 7ah battery is 600mA. Also, by constantly monitoring, we maintain the specified current for 4 hours. But we make sure that the charging voltage for a 12-volt battery is no more than 15-16 volts.
After charging, after about an hour, the battery needs to be discharged to 11 volts; this can be done using any 12-volt light bulb (for example, 15 watt).
After discharge, the battery must be charged again with a current of 600 mA. It is best to do this procedure several times, that is, several charge-discharge cycles.
Most likely, it will not be possible to return the nominal value, since sulfation of the plates has already reduced its service life, and besides, there are other harmful processes taking place. But the battery can continue to be used in normal mode and there will be enough capacity for this.
Regarding the rapid wear of batteries in uninterruptible power supplies, the following reasons were noted. Being in the same case with an uninterruptible power supply, the battery is constantly subject to passive heating from active elements (power transistors) which, by the way, heat up to 60-70 degrees! Constant heating of the battery leads to rapid evaporation of the electrolyte.
In cheap, and sometimes even some expensive UPS models, there is no thermal compensation of the charge, that is, the charge voltage is set to 13.8 volts, but this is acceptable for 10-15 degrees, and for 25 degrees, and sometimes much more in the case, the charge voltage should be a maximum of 13.2-13.5 volts!
A good solution would be to move the battery outside the case if you want to extend its service life.
The “constant low charge” of an uninterruptible power supply, 13.5 volts and a current of 300 mA also affects it. Such recharging leads to the fact that when the active sponge mass inside the battery runs out, a reaction begins in its electrodes, which leads to the fact that the lead of the current leads on (+) becomes brown (PbO2) and on (-) becomes “spongy”.
Thus, with constant overcharging, we get destruction of the current leads and “boiling” of the electrolyte with the release of hydrogen and oxygen, which leads to an increase in the concentration of the electrolyte, which again contributes to the destruction of the electrodes. It turns out such a closed process that leads to rapid consumption of battery life.
In addition, such a charge (overcharge) with a high voltage and current from which the electrolyte “boils” transforms the lead of the down conductors into powdered lead oxide, which crumbles over time and can even short-circuit the plates.
During active use (frequent charging), it is recommended to add distilled water to the battery once a year.
Top up only to a fully charged battery with control of both electrolyte level and voltage. Under no circumstances should you overfill, It's better not to top it up because you can’t take it back, because by sucking out the electrolyte you deprive the battery of sulfuric acid and subsequently the concentration changes. I think it’s clear that sulfuric acid is non-volatile, so during the “boiling” process during charging, it all remains inside the battery - only hydrogen and oxygen come out.
We connect a digital voltmeter to the terminals and, using a 5 ml syringe with a needle, pour 2-3 ml of distilled water into each jar, at the same time shining a flashlight inside to stop if the water has stopped being absorbed - after pouring 2-3 ml, look into the jar - you will see how the water is quickly absorbed and the voltage on the voltmeter drops (by fractions of a volt). We repeat the topping up for each jar with pauses for absorption of 10-20 seconds (approximately) until you see that the “glass mats” are already wet - that is, the water is no longer absorbed.
After refilling, we inspect whether there is an overflow in each battery can, wipe the entire case, replace the rubber caps and glue the lid in place.
Since the battery shows approximately 50-70% charge after topping up, you need to charge it. But charging must be carried out either with a regulated power supply or with an uninterruptible power supply or a standard device, but under supervision, that is, during charging it is necessary to monitor the condition of the battery (you need to see the top of the battery). In the case of an uninterruptible power supply, for this you will have to make extension cords and take the battery outside the UPSa case.
Place napkins or plastic bags under the battery, charge it to 100% and see if electrolyte is leaking from any of the jars. If this suddenly happens, stop charging and remove any stains with a napkin. Using a cloth soaked in a soda solution, we clean the body, all the cavities and terminals where the electrolyte got in, in order to neutralize the acid.
We find the jar where the “boiling” occurred and see if the electrolyte is visible in the window, suck out the excess with a syringe, and then carefully and smoothly pour this electrolyte back into the fiber. It often happens that after topping up the electrolyte is not evenly absorbed and boils up.
When recharging, we monitor the battery as described above, and if the “problematic” battery bank begins to “spout” again during charging, the excess electrolyte will have to be removed from the bank.
Also, under inspection, you should perform at least 2-3 full discharge-charge cycles; if everything went well and there are no leaks, the battery does not heat up (slight heating during charging does not count), then the battery can be assembled into the case.
Well, now let’s take a closer look radical ways to reanimate lead-acid batteries
All electrolyte is drained from the battery, and the insides are washed first a couple of times with hot water, and then with a hot soda solution (3 teaspoons of soda per 100 ml of water), leaving the solution in the battery for 20 minutes. The process can be repeated several times, and at the end, after thoroughly rinsing off the remaining soda solution, a new electrolyte is poured in.
Then the battery is charged for a day, and after 10 days, for 6 hours a day.
For car batteries with a current of up to 10 amperes and a voltage of 14-16 volts.
The second method is reverse charging, for this procedure you will need a powerful voltage source, for car batteries, for example, a welding machine, the recommended current is 80 amperes with a voltage of 20 volts.
They do a polarity reversal, that is, plus to minus and minus to plus, and for half an hour they “boil” the battery with its original electrolyte, after which the electrolyte is drained and the battery is washed with hot water.
Next, a new electrolyte is poured in and, observing the new polarity, they are charged with a current of 10-15 amperes throughout the day.
But the most effective way is done using chemicals. substances.
The electrolyte is drained from a fully charged battery and, after repeated washing with water, an ammonia solution of Trilon B (ethylenediaminetetraacetic acid sodium) containing 2 weight percent Trilon B and 5 percent ammonia is poured in. The desulfation process takes place over a period of 40 - 60 minutes, during which gas is released with small splashes. By the cessation of such gas formation, one can judge that the process is complete. In case of particularly strong sulfation, the ammonia solution of Trilon B should be refilled, having removed the spent solution first.
At the end of the procedure, the inside of the battery is thoroughly washed several times with distilled water and a new electrolyte of the required density is poured. The battery is charged in the standard way to its nominal capacity.
Regarding the ammonia solution of Trilon B, it can be found in chemical laboratories and stored in sealed containers in a dark place.
In general, if you are interested, the composition of the electrolyte produced by Lighting, Electrol, Blitz, akkumulad, Phonix, Toniolyt and some others is an aqueous solution of sulfuric acid (350-450g per liter) with the addition of sulfate salts of magnesium, aluminum, sodium, ammonium. The Gruconnin electrolyte also contains potassium alum and copper sulfate.
After restoration, the battery can be charged in the usual way for this type (for example, in UPSe) and not allowed to discharge below 11 volts.
Many uninterruptible power supply systems have a “battery calibration” function, which can be used to carry out discharge-charge cycles. Having connected a load of 50% of the maximum of the UPS at the output of the uninterruptible power supply, we launch this function and the uninterruptible power supply discharges the battery to 25% and then charges it to 100%.
Well, in a very primitive example, charging such a battery looks like this:
A stabilized voltage of 14.5 volts is supplied to the battery, through a high-power wirewound variable resistor or through a current stabilizer.
The charge current is calculated using a simple formula: divide the battery capacity by 10, for example for a 7ah battery it will be 700mA. And on the current stabilizer or using a variable wire resistor, it is necessary to set the current to 700 mA. Well, during the charging process, the current will begin to drop and it will be necessary to reduce the resistance of the resistor; over time, the resistor handle will come all the way to the initial position and the resistance of the resistor will be equal to zero. The current will then gradually decrease to zero until the voltage on the battery becomes constant - 14.5 volts. The battery is charged.
Additional information on the “correct” charging of batteries can be found
light crystals on the plates are sulfation
A separate “jar” battery was constantly undercharged and, as a result, covered with sulfates, its internal resistance increased with each deep cycle, which led to the fact that, during charging, it began to “boil” before everyone else, due to loss of capacity and removal of electrolyte into insoluble sulfates.
The positive plates and their grids turned into powder in consistency as a result of constant recharging by an uninterruptible power supply in stand-by mode.
Lead-acid batteries are used in cars, motorcycles and various household appliances, where they are found in flashlights and watches and even in the smallest electronics. And if you come across such a “non-working” lead-acid battery without identification marks and you do not know what voltage it should produce in working condition. This can be easily determined by the number of cells in the battery. Locate the protective cover on the battery case and remove it. You will see gas release caps. Based on their number, it will become clear how many “cans” this battery has.
1 bank - 2 volts (fully charged - 2.17 volts), that is, if there are 2 caps, then the battery is 4 volts.
A completely discharged battery bank must be at least 1.8 volts; you cannot discharge it below!
Well, at the end I’ll give you a little idea, for those who don’t have enough money to buy new batteries. Find companies in your city that deal with computer equipment and UPS (uninterruptible power supplies for boilers, batteries for alarm systems), negotiate with them so that they do not throw away old batteries from uninterruptible power supplies, but give them to you, perhaps at a symbolic price.
Practice shows that half of AGM (gel) batteries can be restored, if not to 100%, then to 80-90% for sure! And this is another couple of years of excellent battery life in your device.
