Maintenance free battery
Virtually maintenance-free batteries do not have screw-on cell plugs. Checking the electrolyte level and its density is not necessary for these batteries, because the electrolyte does not evaporate.
These batteries usually have a so-called «magic peephole», which is an optical electrolyte level indicator. By changing the color of the optical indicator, the electrolyte level and the degree of battery charge are determined.
- the color of the optical indicator is green. The condition and charge of the battery is normal.
- the color of the optical pointer is black. The battery is not charged or the charge is too weak.
- the color of the optical pointer is colorless or yellow. The critical state of the electrolyte has been reached. The battery should be replaced.
Conventional battery
A battery of a conventional type differs from a battery that does not require maintenance in that its top cover has screw plugs, see the arrow in illustration 2.16). This battery requires regular checking of the electrolyte level in the cells.
Checking the electrolyte level
The electrolyte should cover the battery plates. Its layer above the plates should be approximately 5 mm thick. For batteries with a plastic rib 1 in the filler hole, the electrolyte level must be at the top of this rib (see illustration 12.16).
Attention! When inspecting the battery, illuminate the openings of the cells with an electric flashlight.
16. Unscrew plugs 2 with a wide screwdriver (see illustration).
17. Top up cells 3 through a funnel, if necessary, with distilled water, bringing the electrolyte level in all cells to normal. It is recommended to use a densimeter with a pipette (see illustration 12.16).
18. Screw plugs 2 cells (see illustration 12.16).
19. Charge the battery and check its charging under load.
Electrolyte Density Check
The degree of electrolyte density in combination with the voltage measurement data allows us to draw a conclusion about its condition.
To check, you need an acid meter, for example, HAZET 4650-1, which can be purchased from specialized stores
The electrolyte temperature of the tested battery must be at least +10°C.
20. Turn off the ignition.
21. Turn out a screw-driver of samples of jellied mouths of cells of the accumulator.
22. Lower the densimeter into the battery cell and remove the electrolyte in such a volume that the float of the densimeter floats freely (see illustration).
The greater the specific gravity (electrolyte density), the higher the float rises.
23. Determine the density of the electrolyte in specific gravity in g / ml or in degrees Baume on the densimeter scale (+° Be) (see illustration). The density of the electrolyte must be at least 1.24 g/ml. If the density is less, then the battery should be charged.
24. Check all battery cells one by one. They should all have about the same density (maximum difference±0.04 g/ml).
If the density of the electrolyte in the cells varies greatly, then a battery malfunction can be assumed.
25. Screw in the cell plugs.
Batteries of the usual type and maintenance-free
Battery test under load
26. Attach a voltmeter to the battery poles. Do not disconnect the wire terminals from the poles
27. Start the engine and read the voltmeter.
When starting the engine, the battery voltage should not fall below 10 volts (at an electrolyte temperature of about +20 (WITH). If the battery voltage immediately drops, and the cells have different electrolyte densities, then a battery malfunction can be assumed.
Battery idle test
Checking the condition of the battery is performed by a voltmeter, which is connected to the poles of the battery.
28. Remove the power wire terminals from the battery poles.
The battery must be disconnected for at least two hours before testing.
29. Connect a voltmeter to the battery terminals and check the voltage (see illustration).
Evaluation of the received testimony:
- 12.5V or higher - battery condition is good.
- 12.4V or less - battery condition is poor. Charge or replace the battery.
30. Connect the battery by attaching the wire terminals to its poles.
Battery charge level | +°Be | g/ml |
Discharged | 16 | 1,12 |
half empty | 24 | 1,20 |
well charged | 30 | 1,28 |