Battery Test Charging
If the battery is suspected of being defective, sulfated, or
unable to take a charge, consult the table.
To test charge a battery, perform the ordinary charging
procedure and monitor the battery voltage and other signs
as mentioned below.
If the battery voltage suddenly jumps to over 13 V just af-
ter the start of charging, the plates are probably sulfated.
A good battery will rise to 12 V immediately and then grad-
ually go up to 12.5 or 13 V in about 30 minutes to an hour
after the start of charging.
If one cell produces no gas bubbles or has a very low
specific gravity, it is probably shorted.
If there does not appear to be enough sediment in a cell
to short the plates, but that cell has a very low specific
gravity after the battery is fully charged, the trouble may
be that there is not enough acid in that one cell. In this
case only, sulfuric acid solution may be added to correct
the specific gravity.
If a fully charged battery not in use loses its charge after
2 to 7 days, or if the specific gravity drops markedly, the
battery is defective. The self-discharge rate of a good
battery is only about 1% per day.
ELECTRICAL SYSTEM 15-29