Electrolyte Density Check
The density of the electrolyte, combined with the voltage measurement data, makes it possible to draw a conclusion about the condition of the battery.
To check, you need a hydrometer, which can be purchased at specialized stores.
The electrolyte temperature of the tested battery must be at least +10°C.
1. Turn off the ignition.
2. Unscrew the plugs of all filler necks of the cells. Before that, if there is one, remove the bar on the battery cover with a screwdriver.
3. Check electrolyte temperature. lowering the thermometer into the battery cell, and take the electrolyte with a hydrometer in such a volume that the float of the hydrometer floats freely. The greater the specific gravity (electrolyte density), the higher the float rises. On the hydrometer scale, the density of the electrolyte can be determined in specific gravity in g / ml or in degrees Baume (+' Be).
4. Charge the battery if the density of the electrolyte in the banks is low. The density of the electrolyte must be at least 1.24 g/ml.
5. Check all battery cells one by one. They should all have about the same density (maximum difference±0.02g/ml). If the density of the electrolyte in the cells varies greatly, then a battery malfunction can be assumed.
Measuring battery open circuit voltage
The battery voltage is measured using a voltmeter connected to the battery poles.
6. Disconnect the battery, see the relevant chapter. The battery must be disconnected from the on-board network at least two hours before the test.
7. Connect a voltmeter to the battery terminals and check the voltage.
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.
Battery test under load
8. Attach a voltmeter to the battery poles. Do not disconnect the wire terminals from the poles
9. 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.
Accumulator charging
10. Remove the battery to charge it with a normal charger or a quick charger. If the battery is not removed from the car, then the terminals from the poles must be disconnected.
Attention! If the battery is charged without disconnecting the terminals, then the electronic control units of the vehicle's units can be damaged.
The temperature of the electrolyte must be at least +10°C during charging.
Precautionary measures
- Do not disconnect the battery while the engine is running.
- Do not short circuit the battery, i.e. do not connect positive (+) and negative (-) poles. If a short circuit occurs, the battery will heat up and may burst.
- Do not expose the battery to naked flames. The electrolyte is corrosive. Avoid contact with eyes, clothing or skin. Wash it off with plenty of water if necessary.
- Do not unscrew caps on ventilated batteries (modern battery models).
- Let the battery thaw if it is frozen. A fully charged battery freezes at about -65°C, a half-discharged one at -30°C, and a fully discharged one freezes already at a temperature of about -12°C.
Charger
11. Remove the battery.
12. Check the electrolyte level before charging. It should be between the minimum and maximum marks on the battery case. Top up with distilled water if necessary.
13. Charge the battery only in a well ventilated area. When charging an installed but disconnected battery, leave the car hood open.
14. Before charging, unscrew the plugs of the battery cells or remove the corresponding cover with a narrow screwdriver. Put plugs or a lid on the holes. In this way, splashing of the electrolyte caused by gases formed during charging is prevented.
If the charging current can be adjusted on the charger, then the charging current should be about 10% of the battery capacity. This means that for a battery with a capacity of 50 Ah, the charging current should be about 5 A. The battery charging time is approximately 10 hours.
15. Connect the positive pole of the battery to the positive pole and the negative pole to the negative pole of the charger.
16. Plug the charger into a power outlet. If necessary, turn on the charger.
17. Check the temperature of the battery by touch, with the palm of your hand, if the battery is charged with direct current. The temperature of the electrolyte during charging should not exceed +55°C. If necessary, interrupt charging or reduce the charging current.
18. Charge the battery until intensive gas formation stops in all cells, and also until the increase in electrolyte density and voltage stop.
19. Turn off (if it is needed) and unplug the charger.
20. Let the battery stand for about 20 minutes.
21. Disconnect the charger wires from the battery poles.
22. Check the battery charge and install it in the tray in the engine compartment.