Battery Charging: Notes

For best results, use an automatic taper-rate battery charger with a voltage capability of 16 volts.

Fig 1: Determining If Battery Should Be Charged

Courtesy of GENERAL MOTORS CORP.

A battery showing a green dot in the hydrometer (1) does not need to be charged unless the J 42000 Battery Tester has shown that the battery needs to be charged.
A battery showing a dark green dot in the hydrometer (2) should be charged unless 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.