User Guide

TROJAN BATTERY
18
Figure 6
5.2.2. Charging Valve-Regulated Lead Acid (VRLA)
Batteries (AGM and gel)
There are various ways to charge VRLA batteries. For optimum performance and life, Trojan recommends
the following:
î Use a 2-phase I-V prole
o Phase 1: Constant current bulk charge
A constant current equal to a percentage of C
20
is applied as the voltage slowly increases.
The recommended currents are as follows:
• AGM: 20% of C
20
• Gel: 10-13% of C
20
The bulk phase ends when the voltage rises to the absorption voltage.
o Phase 2: Constant voltage absorption charge
A constant voltage equal to 2.35-2.45 V/cell is applied as the current slowly declines. The
absorption phase ends when the current stabilizes at a low value of approximately 0.005 x C
20
.
î Refer to Table 6 as well as Figure 7 and Figure 8 for system charging parameters and typical
voltage and current proles.
Recommended Deep-Cycle Flooded/Wet Charging Prole
Note: Charging time will vary depending on battery size, charger output, and depth of discharge.
Voltage
(per cell)
Current
(Amps)
2.45V to 2.70V
(@25°C, 77°F)
2.45V
(@25°C, 77°F)
20% 90% 100%
State of Charge (%)
1-3% C
20
10-13% C
20
Charge Current
Charge Voltage