MerCruiser GM4 - Charging Guide; Volt Battery Recommended Rate* and Time for Fully Discharged Condition 4 A

STARTING SYSTEM - 4A - 590-816462 2-695
Charging Guide
12 Volt Battery Recommended Rate* and Time for Fully Discharged Condition
Twenty Hour
Rating
5 Amperes 10 Amperes 20 Amperes 30 Amperes 40 Amperes 50 Amperes
50 Ampere-
Hours
or less
10 Hours 5 Hours 2-1/2 Hours 2 Hours
Above 50 to
75 Ampere-
Hours
15 Hours 7-1/2 Hours 3-1/2 Hours 2-1/2 Hours 2 Hours 1-1/2 Hours
Above 75 to 100
Ampere-Hours
20 Hours 10 Hours 5 Hours 3 Hours 2-1/2 Hours 2 Hours
Above 100 to
150 Ampere-
Hours
30 Hours 15 Hours 7-1/2 Hours 5 Hours 3-1/2 Hours 3 Hours
Above 150
Ampere-Hours
20 Hours 10 Hours 6-1/2 Hours 5 Hours 4 Hours
* Initial rate for constant voltage taper rate charger
To avoid damage, charging rate must be reduced or
temporarily halted, if:
1. Electrolyte temperature exceeds 125° F (52° C).
2. Violent gassing or spewing of electrolyte occurs.
Battery is fully charged when, over a two hour period
at a low charging rate in amperes, all cells are gassing
freely and no change in specific gravity occurs. For
the most satisfactory charging, the lower charging
rates in amperes are recommended.
Full charge specific gravity is 1.260-1.280, corrected
for temperature with electrolyte level at split ring.
Battery Power as Affected by Temperature
74310
POWER (WATTS) AVAILABLE POWER (WATTS) REQUIRED
100%
83%
61%
45%
80°F
(27°C)
32°F
(0°C)
0°F
(-18°C)
-20°F
(-29°C)
100%
165%
250%
350%