User Manual

12
WARNING: The End Amps or Return Amps setting combined with a sulfated battery
may confuse the charger, cause a state of charge reset prior to actually reaching 100%
SOC. Check specific gravity regularly to confirm the battery bank reaches 100% SOC
as this set point may require adjustment.
LOW VOLTAGE DISCONNECT (LVD OR LVCO)
Many charging systems offer the ability to program a Low Voltage Disconnect (LVD)
or 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
overdischarge. 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.
LVD/LVCO setting is often 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 alternate charging source (ex: generator) when discharge reaches the
low voltage cut-off. To maintain cycle life and prevent heavy discharge, Rolls recommends
setting LVD/LVCO between 1.85-1.95 volts per cell (VPC). This may be adjusted up or
down, depending how often you wish to run the alternate charging source (generator or
alternative power) when the voltage of the battery bank reaches the programmed set point.
WARNING: LVD/LVCO only cuts off the draw from the inverter/ charger. It does not
disconnect all loads from the battery bank. A prolonged draw will eventually lead
to overdischarge and possible battery failure or damage.
OTHER CHARGER MODES
Inverter and charge controller manufacturers may include additional settings. Rolls
recommends contacting the manufacturer for guidance and to better understand how
these settings function. Default settings are typically not in line with the required
charge voltages and time. Charge & Float voltages and Absorption time calculations
are provided by the battery manufacturer and are specific to the make & model.
See Table 2 (a & 2 (b Flooded Charging Parameters.
FLOODED LEAD-ACID BATTERY - CHARGE EFFICIENCY / CHARGE FACTOR
Charge efficiency is a measure of the energy you may take out of a charged battery
divided by the energy required to charge it. Charge efficiency will depend on a number
of factors including the rate of charging or discharging. Charge efficiency for Flooded
deep cycle models is typically 80-85%. This should be reduced 1% per year after the
third (3) year of operation.