Checking the battery state of charge

The density of the electrolyte, together with the measurement of the voltage at the terminals of the battery, makes it possible to draw an accurate conclusion about the degree of charge of the battery. To check, a hydrometer is used, which can be purchased at a specialized store. The greater the density of the electrolyte, the more rises (pops up) hydrometer float. On the hydrometer scale, values are expressed in units of density (kg/cm³).

When measuring the density of the electrolyte, make sure that no drops of electrolyte containing sulfuric acid, which causes corrosion and current leakage, fall from the hydrometer pipette onto the surface of the battery, body and other parts.

The density of the electrolyte in a fully charged battery is 1.28 g/cm³.

The density of the electrolyte in a 25% discharged battery is 1.24 g/cm³.

The density of the electrolyte in a 50% discharged battery is 1.20 g/cm³.

A battery discharged by more than 25% in winter and more than 50% in summer should be removed from the vehicle and recharged.

When measuring the density of the electrolyte, the temperature of the electrolyte should be in the range of 20–30°C. The density of the electrolyte must be measured in each cell (bank) battery. After measuring the density of the electrolyte, you can set the degree of discharge of the battery.

In all cells, the electrolyte must have the same density.

The density of the electrolyte in a fully charged battery is 1.28 g/cm³.

The density of the electrolyte in a 25% discharged battery is 1.24 g/cm³.

The density of the electrolyte in a 50% discharged battery is 1.20 g/cm³.

A battery discharged by more than 25% in winter and more than 50% in summer should be removed from the vehicle and recharged.