Mechanical Gas Fuel System G5.9, G8.3 – 013-007   Batteries

Table of Contents




Use an inductive charging and cranking system analyzer to load-test the state of charge of maintenance-free batteries. If the state of charge is low, use a battery charger to charge the battery. Refer to the manufacturer’s instructions.

Replace the battery if it will not charge to the manufacturer’s specifications or the battery will not maintain a charge.


If conventional batteries are used, remove the cell caps or covers and check the electrolyte (water and sulfuric acid solution) level.


Batteries can emit explosive gas. To reduce the possibility of personal injury, always ventilate the compartment before servicing the batteries. To reduce the possibility of arcing, remove the battery (-) negative cable first and attach the battery negative cable last.

NOTE: Maintenance-free batteries are sealed and do not require the addition of water.

Fill each battery cell with water. Refer to the manufacturer’s specifications.


Refer to the accompanying table to determine the battery state of charge based on the specific-gravity readings.

Battery State of Charge Specific Gravity
@ 27°C [80°F]
100% 1.260 to 1.280
75% 1.230 to 1.250
50% 1.200 to 1.220
25% 1.170 to 1.190
Discharged 1.110 to 1.130

Use a hydrometer to measure the specific gravity of each cell.

NOTE: If the specific gravity of any cell is below 1.200, the battery must be charged.

NOTE: Do not attempt to check the specific gravity of a battery immediately after adding water. If it is necessary to add water to allow use of the hydrometer, charge the battery several minutes at a high rate to mix the electrolyte.

Last Modified:  26-Aug-2003