Currently, manufacturers offer motorists a huge selection of batteries. You can purchase both dry-charged batteries and those already filled with electrolyte at the factory. Further maintenance of the battery can be performed at special service centers. It's convenient and safe. However, there are situations when motorists have to service their car’s battery themselves. To avoid unpleasant consequences, it is important to know how to properly prepare battery electrolyte.
The process of preparing the electrolyte is simple, but requires great care and attention, since it contains pure battery sulfuric acid, which, if it comes into contact with exposed skin or mucous membranes, can cause severe chemical burns.
Before preparing the electrolyte, you need to carefully prepare for this process. To work you will need:
- ebonite container with a volume of at least 5 liters. You can use any other acid-resistant container of your choice. It can be not only ebonite, but also vinyl chloride, polyethylene or ceramics;
- an acid-resistant stick for stirring the electrolyte; ebonite is suitable, but in no case metal;
- distilled water;
- tipping dispenser;
- hydrometer, level gauge, thermometer;
- sulfuric acid. It is important that battery sulfuric acid is used. The use of technical equipment is strictly prohibited;
- the battery itself.
- latex gloves;
- work coat and acid-resistant apron;
- special safety glasses;
- solution ammonia or soda ash 5–10% (to neutralize acid);
- solution boric acid 10% (to neutralize alkali).
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Only after everything you need is at hand, and the performer himself is adequately protected by special clothing, can you begin to prepare the electrolyte. Be sure to make sure you know enough about how to prepare the electrolyte. There are some differences in how to prepare alkaline and acid electrolyte for batteries. 
Instead of distilled water, in desperate situations you can use rain or melted snow water. In this case, you need to make sure that it does not come into contact with iron. Melt water from an iron roof or rainwater collected in an iron container are not suitable for this procedure. When using melt or rain water, it must be passed through the canvas to separate mechanical impurities.
Before making electrolyte for the battery, you should rinse all the dishes prepared for use with distilled water and dry them.
The density of the prepared electrolyte must correspond to the climatic standards in which the battery will be used. Please note that the device can be used outdoors in harsh winter conditions. 
When referring to the battery operating manual, you first need to determine the density of the electrolyte being poured. It should be brought to +25°C. This will prevent it from freezing and resulting damage to the battery.
If the temperature measurement results differ from +25°C, an amendment must be made. It will be necessary to increase the density by 0.0035 for every 5°C above +25°C. If the temperature is below the specified threshold value, the density decreases by 0.0035 for every 5°C. The result will be a density normalized to +25°C.
The next step is to determine the density of the sulfuric acid we use to prepare the electrolyte. It can be equal to the value of 1.83 g/cm3. This is the density of the liquid coming directly from the factory. Taking into account existing demand, it can be a ready-made electrolyte with a density of 1.40 g/cm3.
Video on how to measure electrolyte density:
So, we have determined the required density of the electrolyte we are preparing, and also determined the initial density of the available sulfuric acid. It remains to determine the amount of distilled water needed to make the electrolyte. This value is determined from the table.
Remember that when acid is mixed with water, a chemical reaction occurs. As a result, the final amount of the substance will be slightly lower than the sum of the original components.
After all measurements have been taken, you can begin the procedure for preparing the solution. Let's pour required amount distilled water into a pre-prepared container. Then pour in a measured amount of sulfuric acid. Be sure to follow the specified sequence. Pouring water into acid will result in a violent chemical reaction that can result in dangerous chemical burns. 
It is advisable to cool the electrolyte intended for filling into the battery to a temperature of 150–300°C. Like acid, electrolyte can be stored in tightly sealed glass bottles. The bottle must have a label indicating the date of packaging, the name of the substance and its density. The basics of preparing electrolyte for batteries discussed in this article are in no way a guide to action. This process is quite dangerous, and all its advantages and disadvantages should be carefully weighed before preparation. Maybe, the best option you will contact the service center to receive high-quality and fast service for your battery.
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4.3. Preparation of electrolyte for lead batteries
Electrolyte for lead batteries is prepared by diluting pure sulfuric acid clean water. The acid is usually sold concentrated, specific gravity from 1.835 to 1.840. When diluting concentrated acid, the solution becomes very hot. To avoid danger to the person mixing, it is always necessary to pour the acid into the water, but not vice versa.
Although the amount of heat developed in both cases is the same, the specific heats of water and concentrated acid are completely different. A stream of water entering concentrated acid releases a large amount of heat, which, due to the low specific heat of the acid, causes a strong local increase in temperature. Acid added to water cannot cause such a large increase in temperature due to the fact that the specific heat of water is very high. It is necessary to continuously stir the solution while the acid is being added to the water in order to prevent the heavier acid from sinking to the bottom of the vessel without mixing with the water.
Porcelain, pottery or glass vessels are most suitable for mixing and storing small quantities of electrolyte; but since they crack easily, they should be preferred to vats lined with lead, especially for larger quantities.
No other metal vessels other than lead are suitable.
After diluting the acid, before pouring it into the battery, you must wait until it cools down in order to avoid damage to the plates and separators.
Cooling can be accelerated using a jet of compressed air, but the air must be clean.
You can avoid a strong increase in temperature when mixing acid with water by using ice made from distilled water instead of water. The decrease in temperature occurs due to the fact that the latent heat of fusion of ice is approximately equal to the amount of heat released when sulfuric acid dissolves. Ice, free of water, can be added directly to the acid. The excess of absorbed heat indicates that the solution should reach a temperature below zero, which was actually observed.
To facilitate the preparation of electrolytes of any required concentration, in Fig. Table 4.1 shows the required proportions of acid and water. Battery factories usually provide information about what strength of acid should be used for each given battery.
Rice. 4.1. Preparation of an electrolyte of any specific gravity from concentrated acid with a specific gravity of 1.835.
1- sulfuric acid content,%; 2 – required addition of water by volume; 3 – the same in weight.
4.4. Preparation of electrolyte for cadmium-nickel and iron-nickel batteries
For nickel-cadmium and iron-nickel batteries, the electrolyte is a solution of potassium hydroxide (KOH) or sodium hydroxide (NaOH) in distilled water.
Depending on the ambient temperature in the batteries (Table 4.1), a solution of the appropriate density (concentration) of the main electrolyte component in pure form or with the addition of lithium hydroxide (LiOH) is used.
Nickel-cadmium batteries are designed to operate in the cold at temperatures down to – 40°С, and at temperatures of +35...– 19°С with a composite electrolyte, and at lower temperatures, for example, – 20…– 40°С with electrolyte without the addition of lithium caustic.
At temperatures of – 20...– 40°C in the absence of pure caustic potassium, it is allowed, as an exception, to use a composite electrolyte of caustic potassium and caustic lithium of high density, while the battery capacity is reduced by 10 – 15%. In the absence of a composite electrolyte of caustic potassium and caustic lithium at a temperature of -19...+35°C, you can use a composite electrolyte of caustic sodium with a high density of 1.17 - 1.19 g/cm 3 with the addition of 20 g of caustic per 1 liter of solution lithium, but please note, is not guaranteed.
The durability of batteries is also not guaranteed when working with an electrolyte from a solution of pure caustic potassium with a density of 1.19 - 1.21 g/cm 3, i.e. without the addition of caustic lithium at a temperature of –19... + 10°C. When operating at a temperature of + 10...+50 ° C with the recommended composite electrolyte with a density of 1.1–1.12 g/cm 3 (Table 5.1), the battery capacity is also reduced compared to the nominal, and durability is not guaranteed.
Iron-nickel batteries are designed to operate under the same conditions and with the same electrolyte as nickel-cadmium batteries, but they are more sensitive to low temperatures, so they can be used at temperatures not lower than –20 ° C.
During operation, temperature conditions change sharply depending on the time of year, therefore, in order to more efficiently use the battery capacity, they should be filled with electrolyte, the composition and density corresponding to these conditions.
In addition, it is necessary to systematically monitor the amount of electrolyte, i.e. monitor the level of the latter and maintain it within established limits.
In batteries in use, the electrolyte level gradually decreases due to evaporation, so it must be periodically measured and, if necessary, replenished to normal levels with distilled water. At least after 10 cycles, you need to check the density of the electrolyte and also bring it to normal by adding a solution with a density of 1.41 g/cm 3 or distilled water.
The electrolyte level in batteries must always be at least 5 mm and no more than 12 mm above the edge of the plates.
A decrease in the electrolyte level below the upper edge of the plates or grid, as well as an increase in the density of the electrolyte at positive ambient temperatures, reduces the capacity and durability of the latter. The electrolyte level must be checked and brought to the specified level before each charge. It is checked using a glass tube with a diameter of 5 - 6 mm with marks at a height of 5 and 12 mm from the end. To establish the electrolyte level in the battery, you need to insert the end of the tube with the marks through the filler hole until it stops in the plates or mesh, after which the other end of the tube is closed with your finger. Having removed the tube from the battery at the height of the electrolyte column in it, we determine the level of electrolyte above the upper edge of the plates or grid in the battery. To reduce the electrolyte level in the battery, you can use a pipette or rubber bulb with a glass or plastic tip about 100 mm long. Adding electrolyte or distilled water to batteries can be done using a pipette, rubber bulb or mug through a glass funnel, the size of which is selected depending on the capacity of the batteries. Electrolyte density is checked using a siphon hydrometer.
Checking the density of the electrolyte should be carried out, if possible, before each charge, in each battery, although selective control is allowed in 2 - 3 battery cells. IN as a last resort the check must be carried out at least after 10 cycles in all battery cells.
Thus, electrolyte is necessary not only for the first filling of batteries during formation, but also for replacement, maintaining the density and level of electrolyte in existing batteries, so it must be prepared and always have a reserve.
The following raw materials are supplied for the preparation of electrolyte:
a) battery caustic potassium grade A (solid) or grade B (liquid) and battery caustic lithium;
b) grade A compound alkali – ready mix caustic potassium and caustic lithium in the ratio caustic lithium/caustic potassium = 0.04...0.045;
c) battery caustic sodium (caustic soda) grade A and battery caustic lithium;
d) grade B compound alkali - a ready-made mixture of sodium hydroxide and lithium hydroxide in the lithium hydroxide/sodium hydroxide ratio = 0.028...0.032.
Before preparing the electrolyte, you must make sure that the available chemical components comply with the above requirements and GOSTs. These materials must be stored in hermetically sealed containers. These materials can be supplied in both liquid and solid states in the form of granules, flakes, pieces or ingot.
The preparation of the electrolyte should begin by determining the need for it according to the consumption rate per battery during the first filling, indicated in the table. 4.2.
Having determined the required amount of electrolyte, we will prepare approximately 3/4 of this volume of fresh distilled water. In the absence of the latter, it is allowed to use rainwater collected from clean surface, or water obtained from melting snow, as well as condensate.
Table 4.2
Approximate rate of electrolyte consumption per battery when first filling
Note. When preparing the electrolyte, it is advisable to increase the rate by 10 - 15% to create a reserve for waste and other unforeseen cases.
As a last resort, you can use any raw, clean drinking water(except mineral).
Then, using the data in table. 5.3, we determine the required amount of chemical components: caustic potassium or caustic sodium, as well as caustic lithium for the additive. The consumption of distilled water per 1 kg of solid and per 1 liter of liquid alkali for preparing the electrolyte of the required density is given in table. 4.3.
Table 4.3
Consumption of distilled water required for preparing electrolyte for cadmium-nickel and iron-nickel batteries
To determine the mass of solid alkalis required according to the norm given in table. 19, it is enough to divide:
by three the required amount of water, if it is necessary to prepare a potassium or compound potassium-lithium solution with a density of 1.19 - 1.21 g/cm 3 ;
by two, if it is necessary to prepare potassium electrolyte for operation at temperatures
– 20...– 40° C or composite potassium-lithium density 1.25–1.27 g/cm 3 ;
by five, if it is necessary to prepare a sodium or composite sodium-lithium electrolyte with a density of 1.17 - 1.19 g/cm 3 .
If compound potassium-lithium or sodium-lithium alkali is absent, and caustic potassium, caustic sodium and caustic lithium are available, then the calculation of the need for solid alkalis is carried out according to the same principle as indicated above. It should be borne in mind that the quotient obtained as a result of division also takes into account the mass of caustic lithium.
Surely a significant part of motorists have only superficial knowledge about the structure of their battery, but sometimes you really want to dig around and find out what’s inside, like breaking it down in childhood and looking at it. There is no need to break it, we will try to tell you.
In previous articles, we looked at what a battery consists of. In short, it consists of positive and negative electrodes that alternate, and plastic separators between them. The rest of the space is filled with electrolyte.
So what is an electrolyte? Nothing complicated, the composition of the battery electrolyte is a solution of sulfuric acid and distilled water. So, in order.
Battery Sulfuric Acid
Sulfuric acid is a heavy, clear, oily liquid. It is highly soluble in water and odorless. The process of dissolving acid in water when preparing electrolyte for lead batteries is accompanied by the release of heat.
Sulfuric acid is used in accordance with GOST 667-83 grade A or sulfuric acid of special purity in accordance with GOST 142b2-78. The content of sulfuric acid monohydrate is standardized within 92-94%. Density according to GOST – 1.830 g/cm3. The total content of impurities is no more than 0.03665%, including manganese - no more than 0.0001%, iron - 0.012%, arsenic - 0.0001%, chlorine - 0.0005%, nitrogen oxides - 0.0001%.
Distilled water
The process of preparing electrolyte for lead batteries is impossible without distilled water. The use of technical, drinking and river water is not allowed. It is allowed to use water condensate from steam turbine units with mandatory chemical analysis for iron content, which should not exceed 0.0004%, and copper, with a maximum allowable content of 0.005%.
Electric distillers are usually used to prepare distilled water in laboratories, battery stations, pharmacies and medical institutions.
The distiller model D-1 with a power of 4 kW has a capacity of 5 l/hour, model AD-10 - 10 l/hour. Distillers of other models can also be used. When working with specific models of distillers, you must follow their operating instructions.
It is advisable to analyze the water obtained in distillers at least once every six months. The content of dry substances should not exceed 5 mg/l, ammonia and ammonium salts - no more than 0.05 mg/l, sulfates - no more than 0.5 g/l, chlorides - no more than 0.02 mg/l, calcium - no more than 1.0 mg/.
In addition, the resulting water must be tested for iron, heavy metals and nitrates. The results are summarized in a chemical analysis map, on the basis of which a conclusion is made about the possibility of using the distillate to prepare the electrolyte.
Water must comply with GOST 6709-72.
The cost of distilled water in pharmacies and stores varies from 10 to 20 rubles per 1.5 liters.
The electrolyte for lead batteries is an aqueous solution of sulfuric acid. Sulfuric acid and distilled water are used with the above characteristics. For filling new stationary batteries and those beyond repair, as well as for topping up, an electrolyte with a density of 1.18-1.24 g/cm3 is used.
If sulfuric acid with a density of 1.83 g/cm3 is used to prepare the electrolyte, it is advisable to carry out the work in two stages. At the first stage, an electrolyte with density is prepared. 1.4 g/cm3. It is necessary to ensure its cooling to a temperature of 20C. At the second stage, an electrolyte of the required density is prepared from an electrolyte with a density of 1.4 g/cm3. In a two-stage process, the degree of heating of the sulfuric acid solution will be significantly lower.
You need to prepare the electrolyte in a clean ebonite, earthenware or special plastic container. Of the metal vessels, only lead can be used. The use of glassware is strictly prohibited due to the possibility of destruction due to thermal shock.
First, a measured amount of distilled water is poured into the container, and then the calculated volume of sulfuric acid is poured in a thin stream, while stirring with a glass or hard rubber rod. It is better to add acid in separate portions.
The following rule must be strictly observed: pour acid into water, and not vice versa. It is due to the fact that if you pour water into acid, the water instantly heats up, boils and splashes, carrying with it drops of hot acid, the fall of which on the skin causes burns. That is why all work must be done in rubber boots, cloth overalls and rubber gloves. You can also wear a rubber apron and be sure to wear safety glasses.
To prepare an electrolyte with a density of 1.4 g/cm3 per 1 liter of solution, below we provide a table of what proportions of sulfuric acid and distilled water must be maintained.
Tables of the ratio of sulfuric acid and distilled water
Table 1
For an electrolyte with a density of 1.4 g/cm3, you need to maintain the proportions from the second table.
table 2
To prepare an electrolyte with a density of 1.83 g/cm3, use the third table.
Table 3
When measuring density, hydrometers are used with a measurement range of 1.1-1.4 g/cm3 and a division value no rougher than 0.005 g/cm3 and, since density depends on temperature, thermometers with a measurement range of 0÷50C and a division value of 1C. Thermometers should not have wooden or metal frames. There are no hydrometers with specified measurement limits and accuracy, so a set with narrower measurement ranges is used.
As mentioned above, the process of preparing the electrolyte generates heat. In this case, the measurement of the density of the heated electrolyte will not be correct; accordingly, a correction must be made during the measurement, but it is better to wait until the temperature reaches 20C.
The temperature gradient of density is 0.0007 g/cm3 per 1C. When the electrolyte temperature is higher than the given one, in this case 20C, the calculated correction is added to the measured density value. For example: the actual temperature is 30C, the difference from the given 20C is 10C. Gradient 0.0007 x 10 = 0.07 g/cm3. To the measured density value we add a correction equal to 0.007 g/cm3.
When the actual temperature is 10C, the difference with the given temperature is also 10C. We multiply the gradient equal to 0.0007 g/cm3 by 10, obtaining a correction of 0.007 g/cm3, but in this case the correction is subtracted from the measured density value at a temperature of 10C.
It must be remembered that pouring electrolyte with a temperature above 25C into batteries is unacceptable.
Physical properties of sulfuric acid electrolyte
There is another physical factor that must be taken into account, especially when large volumes of a solution of sulfuric acid and distilled water are prepared. This is the fact that when mixing equal volumes of sulfuric acid and water, after cooling such a solution, its volume will be less than the sum of the initial volumes. To take this factor into account, you need to refer to the fourth table, which shows the volume reduction values for sulfuric acid solutions of different densities.
Table 4 Reduction of solution volume
Viscosity
Viscosity is a property of the electrolyte that most significantly affects the performance of a lead-acid battery. The electrochemical processes that occur during battery operation are of a diffusion nature. The rate of diffusion mainly depends on the viscosity of the electrolyte. It is the diffusion rate that determines the flow of electrolyte to the surface and into the pores of the electrodes during discharge, especially when setting hard (minute, hour) discharge modes.
The higher the viscosity, the slower the diffusion. When the temperature decreases by 25C, the viscosity of the electrolyte increases by 2 times, and at a temperature of -50C it increases by almost 30 times compared to the viscosity at normal temperature. As viscosity increases, capacity decreases. This is why the performance of lead-acid batteries deteriorates at low temperatures. This circumstance must be taken into account when installing sealed batteries with gel (thickened) electrolyte.
Electrolyte resistivity
The resistance of an electrolyte occupying a volume limited by a length of 1 cm and a cross-section of 1 cm3 is calculated by the formula:
where r is the resistivity Ohm cm;
L- length, cm.
S - cross section cm2.
Resistance changes with changes in electrolyte concentration and temperature.
In order to have a minimum internal resistance of the battery, it is advisable to use an electrolyte with the lowest resistivity.
The resistivity values are given in Table 5.
Table 5. Electrolyte resistivities
The specific resistance of the electrolyte increases with decreasing temperature, most significantly at a temperature of 0C.
The freezing point of the electrolyte is important because as the battery discharges, its density and, accordingly, its freezing point decreases. When freezing, the volume of electrolyte increases, which leads to the destruction of the vessel and battery electrodes. The electrolyte with a density of 1.29 g/cm3 has the lowest freezing point. Starter batteries used in harsh conditions have an electrolyte with a density of 1.26-1.30 g/cm3, which does not measure at the lowest possible temperatures.
To determine the freezing temperatures of electrolytes of different densities, use Table 6.
Table 6. Freezing point of electrolytes
Alkaline electrolytes
Typically, caustic potassium and caustic lithium are used to prepare the electrolyte for alkaline batteries.
Caustic potassium (KOH) is a solid white crystalline substance, highly soluble in water. When caustic potassium dissolves in water, heat is released. According to GOST 9285-59, technical caustic potassium is produced in three grades: highest, A and B. The content of caustic potassium in the highest grade is at least 96%, in grade A - 92% and in grade B - 88%. In addition, reactive caustic potash is produced (GOST 4203-435), which contains fewer impurities than technical caustic potassium.
If the electrolyte is prepared from caustic potassium and caustic lithium, then first dissolve the caustic potassium, and then add caustic lithium at the rate of 10-20 g per 1 liter of electrolyte. In order for it to cool down after dilution, as well as for the sedimentation of impurities, it is necessary to leave it in the container for 15-20 hours, closing it tightly with a lid.
After this time, the cleared solution is carefully poured into a clean container, then the density is checked with a hydrometer, and, if necessary, adjusted to normal by adding water, alkali or a ready-made concentrated electrolyte.
The recommended electrolyte density is set by the manufacturer of cadmium-nickel and iron-nickel batteries. If there are no strict recommendations in the documentation, then an electrolyte with a density of 1.19-1.21 g/cm3 at 15C and a content of 10-20 g/l of caustic lithium is used. A solution with these parameters is used when operating the battery at temperatures not lower than -20C. If the temperature is lower, then an electrolyte with a density of 1.25-1.27 g / cm3 without caustic lithium is required.
To restore old alkaline cadmium-nickel and iron-nickel batteries, a potassium-lithium electrolyte with a density of 1.255-1.279 g/cm3 is used with the addition of 69 g of lithium caustic per 1 liter of electrolyte. To prepare electrolytes of the required density, you must follow Table 7.
Table 7. Density of alkaline electrolytes
Preparation of alkaline electrolytes for iron-nickel and cadmium-nickel batteries
In conclusion, we can state that the age of making electrolyte yourself in garages has already come to an end. You can buy a ready-made one at any automotive store and not put yourself at risk when working with chemicals, such as sulfuric acid.
Electrolyte. Preparation rules and starting materials.
Preparation of battery electrolyte.
The electrolyte is prepared from battery sulfuric acid and distilled water. The use of so-called technical sulfuric acid, which has foreign impurities (iron, copper, chlorine, etc.), causes premature failure of the battery. The water used to prepare battery electrolyte must be chemically pure; therefore, distilled water should be used.
Do not use water from a tap or a steam heating system, as such water contains iron. It is also prohibited to use river or well water containing large amounts of salts that are harmful to the battery.
In the absence of distilled water, it is allowed to use rainwater (not collected from iron roofs or in iron vessels), as well as water obtained from melting snow placed in a glass or plastic vessel.
To prepare the electrolyte, you need to use dishes that are resistant to the action of sulfuric acid - ceramic, ebonite or lead.
First, distilled water is poured into the container, and then the acid is poured with continuous stirring. The reverse order of acid filling is not allowed.
During intensive use of the vehicle, it is recommended to reduce the electrolyte density by 0.02 units, but not lower than 1.240, to increase the service life of the batteries.
Most open-type batteries supplied by European companies are required to use sulfuric acid and distilled water as components for preparing the electrolyte, the purity of which must comply with the German standard DIN 43530, which does not correspond to the acid widely used in domestic practice according to GOST 667-73 according to permissible quantity individual impurities. A comparison of the physicochemical parameters of sulfuric acid according to DIN 43530 and another domestic standard GOST 4204-77 (acid for chemical analysis) shows that the latter can be used instead of the acid according to the German standard. Therefore, when dry-charged batteries are supplied without a complete electrolyte, it is possible to use acid in accordance with GOST 4204-77 and water in accordance with GOST 6709-72 when preparing the electrolyte. It is also possible to use acid of special purity in accordance with GOST 14262-78.
The exception is OPzS batteries manufactured by SONNENSCHEIN, for which it is permissible to use an electrolyte composed of premium and first grade sulfuric battery acid in accordance with GOST 667-73 and distilled water in accordance with GOST 6709-72.
For open-type batteries of domestic production (unless otherwise specified), the electrolyte must be prepared from sulfuric acid of the highest and first grade in accordance with GOST 667-73 and water in accordance with GOST 6709-72.
For most supplied imported open-type batteries, the density of the electrolyte being poured should be (1.24±0.005) g/cm 3 at a temperature of 20 °C. Therefore, the density of the electrolyte, measured at a temperature other than 20 °C, must be reduced to the density at 20 °C according to the formula
δ 20 = δ 1 + a(t - 20 °C), where
δ 20 - electrolyte density at a temperature of 20 °C, g/cm3;
δ 1 - electrolyte density at temperature t, g/cm 3 ;
a is the coefficient of change in electrolyte density with a change in temperature by 1 °C, g/cm 3 / ° C (for a specific density value - see Table 8.1; for example, for an electrolyte density of 1.24 g/cm 3 - a = 0, 00072 g/cm 3 /°С);
t - electrolyte temperature, °C.
Before preparing battery electrolyte, you should ensure that the purity of the concentrated acid and distilled water meets the standard requirements. The quality of water and acid must be certified by a factory certificate or a chemical analysis report carried out in accordance with the requirements of the standards.
The preparation of large quantities of electrolyte should be carried out in tanks made of hard rubber or vinyl plastic, or in wooden tanks lined with lead or plastic.
First, water is poured into the tank in an amount of no more than 3/4 of its volume, and then acid is poured into a mug made of acid-resistant material with a capacity of up to 2 liters.
The pouring is carried out in a thin stream, constantly stirring the solution with a stirrer made of acid-resistant material and controlling its temperature, which should not exceed 60 ° C.Considering that the amount of heat released when dissolving sulfuric acid largely depends on the difference between its initial concentration and the final density of the electrolyte, it is advisable to dissolve concentrated sulfuric acid in two steps:
First, concentrated sulfuric acid is diluted to obtain a solution with a specific density of 1,400 g/cm 3 ;
Then the density of the resulting solution is reduced to the required density of the electrolyte, which is no longer associated with significant heat release.
The temperature of the electrolyte poured into batteries should not exceed 35 °C.
The battery, filled with electrolyte, is left for 2 - 4 hours to completely saturate the electrodes. The time after filling with electrolyte before charging should not exceed 15 hours to avoid sulfation of the electrodes.
Filling the battery with electrolyte.
Depending on the climate zone in which cars operate, as well as the time of year, batteries are filled with sulfuric acid solutions of varying densities.
The battery cells should be filled with electrolyte cooled to a temperature not exceeding 25° C.
Before pouring electrolyte into batteries that have not been used, it is necessary to remove the sealing disks from under the plugs (these disks are no longer installed on the battery).
After pouring electrolyte into the battery, you should check its level in the cells using a glass tube 100-150 mm long, outer diameter 6-8 mm and inner diameter 5-6 mm. Marks should be placed on the tube at a distance of 10 and 15 mm from the lower end.
When measuring the level, the tube should be lowered into the element up to the safety flap, then clamp the upper hole with your finger and remove it. The column of electrolyte remaining in the tube indicates its level above the cell plates.
The electrolyte level should be 10-15 mm above the top edge of the plates.
It's no secret that modern batteries run on electrolyte. This substance allows batteries to accumulate charge and release it in the form of final electricity during operation. One of the most common electrolytes is alkaline, which is actively used in batteries of the same name. This substance works well in battery operation, but also has some disadvantages. We will talk in more detail about them, the essence of the alkaline electrolyte and the principles of its operation in today’s article.
A few words about alkaline electrolyte
Alkaline electrolyte is one of the main components of batteries of the same name. Today, a similar substance is used in many batteries, so the relevance of its consideration is quite high. The typical electrolyte composition for alkaline batteries is:
- or from caustic potassium and lithium compounds;
- or from sodium hydroxide and potassium hydroxide, as well as the same lithium.
Any of the compounds noted above in a certain concentration is diluted with distilled water, which forms an electrolyte solution for alkali. In terms of formation, it is liquid and appears, at first glance, as ordinary water.
At the moment, in the field of rechargeable batteries, there are two typical, competing types of electrolytes, namely:
- those we are considering are alkaline;
The former, compared to the latter, are more reliable and durable battery components. In addition, alkaline electrolytes are superior to acidic ones in many respects, with the exception of one BUT - they are not capable of producing a starting current. This point seriously undermined the use of “alkali” in car batteries, so acid electrolytes and corresponding batteries are much more common in modern cars.
Life time
Potassium-lithium alkaline electrolyte, with proper operation and high-quality preparation, is one of the longest serving in its field. It has been experimentally proven that this liquid can withstand more than 1000 charge-discharge cycles, which is simply a huge number of such procedures. However, when using alkaline electrolytes, it is worth keeping in mind the factors that reduce their service life. The most important of these are the following:
- Frequent insufficient battery charging;
- Systematic deep discharge of the battery;
- Insufficient amount of electrolyte in the separator;
- Long-term use of electrolyte at high ambient temperatures;
- Fluid operating temperatures are too high and frequent.
By avoiding the presence of these factors specifically in your situation, you can extend the service life of the battery and alkaline electrolyte separately significantly. Note that when using such liquids, it is also important to constantly refill the battery with the same type of electrolytes. Otherwise, the battery life will be reduced.
Procedure for filling electrolyte into an alkaline battery
Let’s say that an alkaline battery has stopped holding a charge or has completely failed. What to do in such a situation? Most likely, you will have to change the potassium-lithium alkaline electrolyte, but before replacing or topping it up, it is important to make sure that:
- battery electrodes are intact;
- the separators and their plates were not crumbled;
- The battery does not work precisely because it is discharged.
If these points have been successfully confirmed, then there is no doubt about the need to fill the electrolyte. The procedure for this is as follows:
- Remove the battery from the car;
- Place it in a place protected from third parties, children and sources of current, fire, water, and also convenient for working with the battery;
- Prepare yourself with a complete set of protective clothing (at a minimum, safety glasses and gloves), a tool for opening the battery cover, and alkaline electrolyte for filling. The latter, by the way, can be bought both in a store (the cost starts from 30 rubles) and prepared at home;
- Then carefully remove the battery cover and begin to fill in the electrolyte, following the corresponding marks;
- After the fluid has been added to the required level, return the battery to its original condition and install it back on the car.
Note! Before starting work, make sure that you have an alkaline battery and the electrolyte used in it is based on alkali. Please note that if you fill the electrolyte incorrectly, you can render the battery unusable.
When completely or partially changing the electrolyte in an alkaline battery, be sure to charge it in high mode (about 12 hours) or normal mode (6 hours). In other cases, accelerated charging (about 3 hours) with a 2-fold increase in normal current is acceptable.
Rules for charging an alkaline battery
Since the functioning of an alkaline electrolyte largely depends on how exactly the battery into which it is filled will be charged, it would not be amiss to consider the basic rules for charging the corresponding batteries. In general, their list is as follows:
- Charge the battery exclusively at medium and high current levels, since this practice has a positive effect on both the condition of the alkaline electrolyte and the condition of the battery;
- During the charging process, be sure to ensure that the electrolyte containing lithium does not exceed a temperature of more than 45 degrees Celsius and 35 for electrolytes without lithium;
- It is necessary to insulate alkaline batteries during charging only if the ambient temperature is less than minus 30 degrees Celsius. In other cases, the batteries are charged as usual;
- When charging the battery, make sure that the electrolyte does not splash out, as this is not permissible;
- After 10 charge-discharge cycles, always check the electrolyte level and, if necessary, top it up.
A clear sign that the alkali battery was charging correctly will be the presence of 1.4-1.45 Volts of voltage at the beginning of charging the battery and 1.75-1.85 Volts at the end.
Learning to prepare alkaline electrolyte
At the end of today’s material about alkaline electrolytes for batteries, it would be useful to pay attention to how to make them at home. To achieve this goal, first of all, you need to prepare:
- starting materials for preparing the electrolyte: distilled water (GOST 6709-72), potassium hydroxide KOH grades A, B(GOST 9285-69) and lithium oxide hydrate Li(OH)3 (GOST 8595-75);
- iron, cast iron or plastic containers with tight lids;
- similar items for stirring the solution;
- A hydrometer is a device that is required to measure the density of a prepared electrolyte.
Direct preparation of alkaline electrolyte is carried out as follows:
- The required amount of distilled water is poured into the vessel;
- With gentle movements, alkali is either poured into the liquid or placed with steel pins;
- After this, the solution is stirred with special devices, and its density is adjusted to the required indicators by using a hydrometer, as well as adding certain substances to the electrolyte.
Important! The density of the alkaline electrolyte is determined using special tables, taking into account the temperature of use of the battery and the specific characteristics of the battery. As a rule, it is about 1.25-1.27 grams per cubic centimeter.
The prepared electrolyte is poured into glass containers, which are closed with tight rubber stoppers. It is advisable to store alkaline electrolyte away from children and the sun. In addition, containers with the substance should be marked accordingly.
With this, perhaps, the most important provisions on the issue under consideration today have come to an end. As you can see, alkaline electrolyte is the most important component of batteries of the same name, requiring systematic checking and replacement. We hope the material presented above was useful to you. Good luck with car repairs and on the roads!
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