Rolls Surrette User Manual

EXAMPLE:

2 strings of 6 Volt 6 CS 25P models

20 hr AH rate = 820 AH x (2 strings) = 1640 AH

I = 10% of 1640 AH = 164 Amps.

T = 0.42 x 1640/164 = 4.2 hrs

If charger output is 120 Amps max, 120 is used.

T = 0.42 x 1640/120 = 5.75 hrs

FLOAT CHARGE

When the Absorption charge is completed, the batteries require a certain

amount of voltage to maintain a full charge when no load is applied. This Float

voltage maintains the battery bank at a constant full state of charge. To prolong

battery life, the Float settings on the power supply should be adjusted to the

voltage indicated in Table 2 (a) & 2 (b) Flooded Charging Parameters. Higher

or lower voltage settings may result in unnecessary overcharge or sulfation.

END AMPS OR RETURN AMPS

As batteries near full capacity the charge current drops. End Amps or Return

Amps generally refers to the lowest amount of current (Amps) running from the

charger when the batteries have reached full capacity and are no longer accepting

a charge. Some charges will measure the actual current output. If the charge

current drops to the End Amps or Return Amps set point, this will trigger the

charger to shut off. This setting is typically 2%-3% of the 20 Hr AH rating (C20)

of the battery bank. Rolls recommends setting this at 2% for new installations.

WARNING: This setting combined with a sulfated battery can confuse the charger and

cause a state of charge reset prior to actually hitting 100% (SOC) state of charge.

LOW VOLTAGE DISCONNECT (LVD OR LVCO)

Many charging systems offer the ability to program a Low Voltage Disconnect

(LVD) or Low Voltage Cut Off (LVCO), which triggers an alternate power source

(often a generator) to turn on and begin charging the battery bank. When the

programmed low voltage setting is reached, the system initiates the charge

source which then safeguards from overdischarging the battery bank. By

default, this may be set by the charger manufacturer at 1.75 volts per cell (VPC).

Always verify the default settings and adjust as required.

Low Voltage Disconnect setting is a personal preference. Deep cycle batteries

are intended to be discharged no more than 50%. Allowing the battery bank to

discharge to a lower voltage will reduce over all cycle life. Alternatively, a higher

set point may result in more frequent use of the charging source (ex: generator)

when discharge reaches the low voltage cut-off.