Battery Testing should be done in multiple tests. The most accurate method is measurement of specific gravity along with battery voltage. To measure specific gravity, use a temperature compensating digital hydrometer and to measure voltage use a digital D.C. Volt meter. A quality load tester is also a good tool if you need to test sealed batteries.
No matter which method of testing you choose, you must first fully charge the battery and then remove the surface charge. To remove surface charge the battery must be discharged for several minutes.
| State of Charge |
Specific Gravity |
Voltage |
| |
|
12V |
6V |
| 100% |
1.265 |
12.7 |
6.3 |
| *75% |
1.225 |
12.4 |
6.2 |
| 50% |
1.190 |
12.2 |
6.1 |
| 25% |
1.155 |
12.0 |
6.0 |
| Discharged |
1.120 |
11.9 |
6.0 |