Rolls Surrette User Manual

VRLA ABSORPTION CHARGE TIME

Where : T = 0.42 x C /I

T = ABSORPTION CHARGE TIME

C = 20 hr RATED CAPACITY (total battery bank)

I = Charging Current (Amps) (recommended 20% to 35% of C20 discharge rate)

0.42 = ( 20%/50%) + 5% (5% is added due to losses)

EXAMPLE:

2 strings of 6 Volt S6-460AGM models

20 hr AH rate = 415 AH x (2 strings) = 830 AH

I = 20% of 830 AH = 166 Amps

T = 0.42 x 830/166 = 2.1 hrs

VRLA FLOAT STAGE AND TERMINATION

The charger can maintain the End Amps current indefinitely or until the charger

is shut off or unplugged. This stage is ideal to maintain battery state of charge.

Make sure the temperature compensation is programmed as specified in Table

5 & 7 (-4mV/°C/cell or -2mV/°F/cell) or manually adjust the voltage setting

for temperatures varying from 25°C (77°F). As the temperature decreases,

the voltage should increase and vice versa. The profile in Table 5 & 7 can be

used with or without the float stage. Without the float stage, recharge can be

terminated based on time (this will need to be determined as it will vary with

depth of discharge and charge current) or percentage recharge (105%-110%).

AGM CHARGE VOLTAGE QUICK REFERENCE

NOTE:

Set the charge voltage at 2.45 volts per cell (VPC) when using

temperature compensation. Higher or lower voltages may cause incorrect

adjustments in charge voltage. If a sensor is not used, you must manually

adjust charging voltages based on the battery temperature when in use,

not just ambient temperatures.

TABLE 5: AGM Charge Voltage

NOTE:

If charger output is

120 Amps max, 120 is used

T = 0.42 x 830/120 = 2.9 hrs