Battery Specific Gravity, Measuring in All Cells
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Special tools, testers and auxiliary items required
- Refractometer T10007 or
- Commercially available hydrometer
Prerequisites
- The temperature of the battery acid must be at least +10 C.
Procedure
In conjunction with battery test → Battery, Testing with Midtronics Battery/Starting/Charging System Analyzer MCR340A , the specific gravity measurement gives information about the condition of the battery.
CAUTION:
Risk of injury from direct exposure to battery acid.
- Follow accident prevention regulations when working with battery acid → 27 - Battery, Starter, Generator, Cruise control .
- Wear protective eyewear and clothing → 27 - Battery, Starter, Generator, Cruise control .
NOTE:
- Specific gravity of electrolyte can be checked immediately after charging battery.
- Remove all battery cell sealing plugs.
- Dip hydrometer into battery cell and siphon off enough electrolyte until float floats freely in electrolyte.
- The higher the specified weight of the siphoned battery acid, the higher the float will float.
- The acid density of the electrolyte can be read off in kg/dm 3 on the hydrometer scale (specified density of the battery acid).
- Compare hydrometer reading to values given in table.
| Charge condition | Electrolyte density in kg/dm 3 | |
| in normal climates | in the tropics | |
| Discharged | 1.12 | 1.08 |
| Partial charge | 1.20 | 1.16 |
| Fully charged | 1.28 | 1.23 |
Specified acid density must be at least 1.24 kg/dm 3 in moderate climate zones. If the acid density in all battery cells is too low:
- Charge battery and repeat acid density test.
| Example 1 | ||||||
| Battery cell | 1 | 2 | 3 | 4 | 5 | 6 |
| Electrolyte density per cell in kg/dm 3 | 1.24 | 1.25 | 1.25 | 1.10 1) | 1.24 | 1.25 |
| 1) Acid density in cell 4 is too low (deviation greater than 0.03 kg/dm 3 ). | ||||||
| Example 2 | ||||||
| Battery cell | 1 | 2 | 3 | 4 | 5 | 6 |
| Electrolyte density per cell in kg/dm 3 | 1.26 | 1.26 | 1.25 | 1.14 1) | 1.18 1) | 1.24 |
| 1) Acid density in cells 4 and 5 too low (deviation greater than 0.03 kg/dm 3 ). | ||||||
- If the specified values are not reached, replace battery.
NOTE:
- The measured values for the specific gravity of the individual battery cells must not deviate by more than 0.03 kg/dm 3 , otherwise the battery should be replaced.
CAUTION:
Risk due to leaking battery acid.
- To ensure the various battery connection systems are free of leaks, the batterys original sealing plugs must be installed in the battery openings. Only replace missing or damaged sealing plugs with the same type of original plugs.
- The sealing plugs must be equipped with an O-ring.
- If the specified values are reached, reinstall battery cell sealing plugs.
NOTE:
- If the battery must be replaced, follow the disposal regulations → 27 - Battery, Starter, Generator, Cruise control .