Battery, Checking

A weak battery can be caused by:
- Generator (GEN) belt slipping (replace belt if glazed)
- Ground (GND) straps corroded, loose or broken
- Generator (GEN) or Voltage Regulator (VR) malfunctioning
- Generator (GEN) warning light -K2- bulb failed
- Poor Ground (GND) connection between Generator (GEN), warning light -K2- socket and circuit board

Battery and cable terminals should be cleaned and coated with acid resistant grease to prevent corrosion.

Visual checks
Check for:
- Cracked or leaking case
- Loose or corroded terminals
- Low electrolyte level (below MIN mark). If electrolyte is low, refill with distilled water and charge battery for several minutes after cells begin gassing (boiling).

CAUTION: DO NOT overfill. Overfilled batteries can boil over. Too little electrolyte reduces the service life of the battery.

Hydrometer Test (specific Gravity), Batteries With Removable Caps

NOTE: Calibration of hydrometer must be checked frequently to ensure accuracy.

CAUTION: DO NOT expose a fully discharged battery to freezing temperatures; the battery will be damaged.

- Test electrolyte in all cells.
Average specific gravity should be at least 1.225
- Correct for electrolyte temperature if necessary:
- For every 10 °F above 80 °F, add 0.004 to hydrometer reading
- For every 10 °F below 80 °F, subtract 0.004 from hydrometer reading

Specific gravity % of charge
1.265 100%
1.225 75%
1.190 50%
1.155 25%
1.120 0%

If specific gravity is above 1.225:
- Load test battery.

If specific gravity is below 1.225:
- Charge battery.

If specific gravity varies by more than 0.050 between cells:
- Replace battery.