Electrolyte Density Check
The density of the electrolyte along with the voltage give an indication of the degree of discharge of the battery. A hydrometer is used to check the density. The greater the specific gravity (electrolyte density), the more float floats. On the hydrometer scale, you can determine the density of the electrolyte in g / ml or in degrees Baumé (+°Be). Density values (at an electrolyte temperature of +20°С) should be next.
Discharge degree | Gasoline engine, +°Be g/ml | Diesel engine +°Be g/ml | ||
completely discharged | 8 | 1.06 | 11 | 1.08 |
half discharged | 20 | 1.16 | 22 | 1.18 |
normally charged | 30 | 1.26 | 32 | 1.28 |
Check each section of the battery in sequence. All sections must have the same electrolyte density (maximum difference is not more than 0.04 g/ml). A large difference indicates battery failure.
Battery test under load
Connect a voltmeter to the battery terminals.
Start the engine and measure the voltage.
When starting the engine, the voltage of a fully charged battery must not fall below 8 V (at an electrolyte temperature of +20°С).
If the battery voltage drops sharply, and the density of the electrolyte in the sections differs significantly from each other, then this is a sign of a defective battery.
The battery voltage can be measured with a special tester.
Control values
Capacity, Ah | Cold battery current, A | Current strength with a loaded battery, A | Minimum voltage after 5-10 sec |
54 | 265 | 220 | 9.4 V |
64 | 380 | 300 | 9.0 V |
88 | 395 | 300 | 9.5 V |
Attention: If during the measurement process the voltage falls below the set value for 10 seconds, the battery is either discharged or has failed.