PREVOST H3-41 Maintenance Manual page 231

FIGURE 56 ALLIGATOR CLAMP POSITION– TYPICAL
AGM BATTERY
WARNING
Always turn off the charger before connecting
or disconnecting to a battery.
NOTE
The charge rate must be doubled when the
batteries are charged by the booster block,
because of the series-parallel circuit.
AGM (Absorbed Glass Mat) batteries require
a voltage-limited charger, ideally fitted with a
battery temperature sensor for temperature
correction of charging parameters.
Do not manually charge AGM batteries. Look
for the following voltage values on your
voltage-limited charger.
Charge voltage: 13.8-14.6 Volt @77°F (25°C)
Float voltage: 13.4-13.6 Volt @77°F (25°C)
Charging AGM battery on a typical constant
current or taper current charger – even once –
may greatly shorten its life.
• The maximum charge rate in amperes
should be no more than 1/3 of the battery's
reserve capacity minute rating.
State-of-charge is estimated from the OCV
•
(open-circuit voltage). Typical values are
shown on the charging time table below.
CHARGING TIME TABLE FOR A SINGLE BATTERY
OCV STATE OF
CHARGE
(AGM)
12.8V 100%
12.6V 75%
12.2V 50%
12.0V 25%
11.8V 0%
CAUTION
AGM Battery Charging Considerations
Many common battery chargers are not fully
compatible with AGM batteries, however; they
will not ruin the battery if used a few times
over the battery's life.
Adversely, not all chargers are really AGM
compatible and can do significant damage to
an AGM battery. Large "wheeled chargers"
found in many shops, which exceed 15.4 volts
must be avoided.
If an AGM battery needs to be charged
outside of the vehicle's charging system,
charging voltage should be 13.8 –14.8 @
77°F (25°C). Not to exceed 30 Amps.
The time required for a charge will vary
according to the following factors:
Temperature
A longer time will be needed to charge any
battery at 0 F (-18
o
a fast charger is connected to a cold battery, the
current accepted by the battery will be very low
at first, and then in time, the battery will accept a
higher rate as it warms.
State of Charge
For example, a completely discharged battery
requires more than twice as much charge than a
half-charged battery. Since the electrolyte is
nearly pure water and a poor conductor in a
completely discharged battery, the current
accepted is very low at first. Later, as the
charging current causes the electrolyte acid
content to increase, the charging current will
likewise increase.
PA1621 Maintenance Manual All Series | Revised Sept 2019
SECTION 06: ELECTRICAL
CHARGER MAXIMUM RATE
30 A 20 A
Ready to use
0.9 1.3
1.9 2.7
2.9 4.3
4.0 5.7
C) than at 80 F (27 C). When
o o o
67
10 A
2.5
5.1
7.8
10.7