Battery check

Electrolyte level

Cars can be equipped with a maintenance-free type battery that does not require any maintenance during operation. Such batteries are distinguished by a flat removable or non-removable battery compartment cover. In addition, there is a corresponding sticker on the battery.

If the vehicle has a battery "traditional" type, it is periodically necessary to check the electrolyte level and, if it is below the upper edge of the plates, replenish it by adding distilled water. The electrolyte level must be between the marks "MIN" And "MAX" on the translucent wall of the battery case (pic. A:15), or between the upper edge of the plates and the lower cut of the filler neck. Do not raise the electrolyte level above normal. It is advisable to start the engine immediately after topping up with distilled water so that the water mixes well with the electrolyte - this will prevent the electrolyte from freezing in cold weather.



If you need to frequently add water to the battery, you should find out the reason for this. In particular, the battery "boil away" due to increased voltage in the charge circuit due to a malfunction of the voltage regulator. Check the electrical system and repair as soon as possible (see chapter "Engine electrical equipment"). If you only need to add electrolyte to one of the battery compartments, carefully inspect the case for cracks that may be causing electrolyte leakage. If a leak is found, eliminate its cause.

NOTE: To avoid electrolyte splashing, start charging the battery no earlier than half an hour after adjusting the electrolyte level (unless the battery is charged by the car's own charging system).

General health and battery level

It is impossible to measure the density of the electrolyte in sealed, maintenance-free batteries, therefore, to assess the general condition, the battery should be removed from the car, fully charged and taken to a battery workshop for a control discharge. In addition, you can assess the condition of the battery using a load plug.

For a conventional battery, the charge level is checked by measuring the density of the electrolyte in each compartment with a special hydrometer, which can be purchased at most auto supply stores. When checking the tightness, be careful not to spill the acid on your skin or clothing.

Check the density in the following order:

• 1. Unscrew the battery compartment plugs or remove the cover. Lower the end of the hydrometer into the hole in one of the sections of the accumulator (pic. A:15).
• 2. Slowly draw electrolyte into the hydrometer until the float rises.
• 3. The division of the float scale, which is at the level of the electrolyte, corresponds to the density of the electrolyte in this section. Read the hydrometer readings.
• 4. Slowly and carefully release the electrolyte back into the battery, then repeat the measurement in all other sections of the battery. A fully charged battery should have an electrolyte density of 1.275 g/cm³. Density 1.120 g/cm³ corresponds to a fully discharged battery (see section "Technical data").

If the density is low, battery needs to be charged and again check the density of the electrolyte no earlier than one hour after charging. If the density is still low, the battery needs to be replaced.

Battery terminals and wires

To ensure reliable contact, the battery terminals must be well tightened. If a white precipitate has formed on and around the terminals, the wires should be disconnected from the battery, the terminals cleaned with a wire brush and the wires reattached, lubricating the connections with technical petroleum jelly. When cleaning the terminals, be careful not to spread the white residue as it can cause increased corrosion. Tighten connections securely. In addition, check the reliability of the connection with the body of the wires "masses" engine and battery.