Checking the electrolyte level
The electrolyte level must be between the marks «MIN» and «MAX», applied to the translucent battery case. During operation of the battery, the electrolyte level gradually decreases, as the water that is part of it evaporates. Therefore, it is necessary to check its level every 4 months. It is not allowed to operate the battery with an electrolyte level below the mark «MIN», To restore the electrolyte level, only top up with distilled water.
If it is determined that the cause of the low level is sloshing, then it is necessary to add electrolyte of the same density as that remaining in the battery cell. If the level is above normal, then the electrolyte must be taken with a rubber bulb.
Checking the degree of discharge of the battery
To determine the degree of discharge in case of battery failure, and also every 4 months, measure the density of the electrolyte with a car densimeter and compare it with the data in Table. 20.
If the battery is discharged by more than 25% in winter and 50% in summer, then it should be removed from the vehicle and recharged.
During the density measurement, make sure that the battery surface, body and other parts do not get electrolyte that causes corrosion, current leakage, etc.
The density of the electrolyte depends on the temperature. With a change in the latter for every 15°C, the density changes by approximately 0.01 g / cm3. Therefore, if the electrolyte temperature differs from 25°C, then the temperature correction should be added or subtracted from the densimeter readings:
To avoid erroneous results, do not measure the density of the electrolyte in the following cases:
- if its level does not correspond to the norm;
- when the electrolyte is too hot or too cold. The optimum temperature of the electrolyte when measuring density is 15–25°C;
- immediately after topping up with distilled water. Wait until the electrolyte is mixed. If the battery is low, this may take several hours;
- after a few starts. You should wait until a uniform density of the electrolyte in the battery cells is established;
- at «boiling» electrolyte. You should wait until the bubbles in the electrolyte collected in the densimeter pipette rise to the surface.
If, when measuring the density of the electrolyte, it is found that it is excessively high (1.3 g/cm3 and higher), then it is necessary to take a part of the electrolyte from the cell, add distilled water instead, wait until the electrolyte is mixed, and again measure the density.
Battery charge
The battery removed from the vehicle must be carefully cleaned, especially its upper part, and the electrolyte level checked. The battery is charged with a current of 1.8 A with the plugs turned out. When charging the battery, it is necessary to periodically check the temperature of the electrolyte and prevent it from rising above 40°C. If the temperature reaches 40°C, then reduce the charging current by half or interrupt the charge and cool the battery down to 27°C.
The charge stops when abundant gas evolution begins in all battery cells, and the voltage and density of the electrolyte during the last 3 hours of charging remain constant.
The density of the electrolyte of a charged battery at 25°C must correspond to the data in Table. 20 for each climatic region.
If at the end of the charge the density of the electrolyte (determined taking into account the temperature correction) differs from that indicated in the table. 20, then correct it. At increased density, a part of the electrolyte is taken and distilled water is added. If the density of the electrolyte is below normal, then, having taken it out of the cell, add an electrolyte of increased density (1.4 g/cm3).
After adjusting the density of the electrolyte, continue charging the battery for another 30 minutes to mix the electrolyte. Then the battery is disconnected and after 30 minutes its level is measured in all cells. If the electrolyte level differs from the norm, then it is brought to the recommended value, as indicated above.