Electricity is required for the operation of electrical appliances and the ignition system of a car. There are two power sources in the car: a storage battery (AKB) and a generator. Both devices supply the vehicle electrical system with 12 V direct current. Sometimes it is necessary to fill the batteries with distilled water.
Why does the battery contain distilled water?
The generator only generates electricity when the engine is running and serves as the main "supplier" of electricity. The start of the engine is provided by the battery, but it is an auxiliary source of electricity.
Attention! Lead-acid batteries are often used on cars. They work through a chemical reaction that occurs between the lead plates and the lead dioxide in the electrolyte.
The battery consists of 6 galvanic cells located in separate compartments and placed in a common housing. Each of the compartments has a filler plug through which electrolyte is poured and subsequently replenished with distilled water.
The electrolytic solution has the following composition:
- sulfuric acid (H2SO4);
- distilled water (H2O).
The electrolyte is prepared in a glass container by mixing sulfuric acid with water. Reagents react to generate heat, the plastic container may melt. The proportion depends on the desired density of the solution.
Caution! When mixing, pour water into acid and not otherwise.
Why add distilled water?
During the operation of the car, there is a periodic discharge and charge of the battery. When starting the engine, the starter draws a lot of current. At the moments of cranking up the engine by the starter to the revolutions required for starting, the current value reaches 320 - 400 A. Frequent starts will drain the battery.
Charging occurs from a generator (at the time the engine is running) or a charger when the density of the electrolytic solution decreases.
Important! Topping up is carried out in order to replenish the boiled off part of the water from the electrolyte. Water should only be distilled, tap water is not suitable due to the presence of impurities in it.
Water boils away in the following cases:
- With an overestimated content of antimony in the grids of the battery plates. Antimony is added to the lead strength of the plates during fabrication. And it also promotes the splitting of water into hydrogen and oxygen.
- At the end of the charge. When the battery is fully charged, further charging causes the electrolyte to boil violently and water was consumed.
- When the voltage from the generator is exceeded to recharge the battery. This happens when the regulator relay fails, which limits the voltage supplied to the battery. At idle, without the included consumers, it should be in the range of 13.7 - 14.2 V. The high voltage causes a constant recharge and the water boils away very quickly.
- In case of sulfation or malfunction of the battery galvanic cells. Sulfation is the coating of the surfaces of the plates with lead sulfate. It comes from long-term use of the battery.
Note! Desulfation and battery recovery can be performed using charge-discharge cycles with low currents.
When to add distilled water to the battery?
Maintaining the fluid level is one of the essential steps in battery care. For different battery designs, the need for adding water is determined in one of the following ways:
- on the risks "min" and "max" within the limits of which it is necessary to maintain the electrolyte level, if the battery case is sufficiently transparent;
- by the color of the indicator, which is screwed in instead of one of the plugs or is located separately;
- along a special constructive protrusion inside the compartment, which is noticeable when the plug is unscrewed and the electrolyte must reach this protrusion.
A glass or plastic tube will help to clarify the level. It is dipped into the solution until it touches the separator mesh. Pinch the top edge with your thumb and pull it back out. The level of liquid remaining in the tube is measured with a ruler. It should be 1.2 - 1.5 cm.
Do you always need to top up distilled water into the battery?
With a decrease in the electrolyte level on the serviced batteries, it is necessary to top up with distilled water. Maintenance-free batteries do not allow for this due to design features (there are no traffic jams).
Reference! There are times when electrolyte is poured into the battery. This is done only when changing the solution (when cleaning the battery) or when commissioning a dry-charged battery.
As a conclusion
A properly working battery needs to be refilled with water once every three months. They do it as follows:
- determine the need for water replenishment to the required level;
- disconnect the negative terminal without removing the batteries from the car;
- unscrew the plugs on the battery, add distilled water;
- put the current source on charge.
After the end of the charge, the density of the electrolyte is specified. The norm is in the range of 1.25-1.27 g / cm3 (at T = 250C). The density value is specified for each climatic zone individually.