Battery Charging

Fig 1: Identifying Dots In Hydrometer

Courtesy of GENERAL MOTORS CORP.

For best results, use an automatic taper-rate battery charger with a voltage capability of 16 volts.
A battery showing a green dot in the hydrometer (1) does not need to be charged unless the J 42000 has shown that the battery needs to be charged.
A battery showing a dark dot in the hydrometer (2) should be charged unless the J 42000 has indicated no charge is needed.
Do not charge a battery when the built in hydrometer is clear or yellow in the center (3). Tap the hydrometer lightly in order to dislodge any air bubbles. The bubbles may cause a false indication. If the hydrometer is still clear or yellow, replace the battery.
The charging area should be well ventilated.
Do not charge a battery that appears to be frozen; allow the battery to warm to room temperature and test it before charging.