This same percentage can be applied to a 12V battery bank with a 6V
midpoint.
In case of a 48V battery bank consisting of 12V series connected batteries,
the % influence of one battery on the midpoint is reduced by half. The
midpoint alarm level can therefore be set at a lower level.
5.2.3 Alarm delay
In order to prevent the occurrence of alarms due to short term deviations
that will not damage a battery, the deviation must exceed the set value
during 5 minutes before the alarm is triggered.
A deviation exceeding the set value by a factor of two or more will trigger
the alarm after 10 seconds.
5.2.4 What to do in case of an alarm during charging
In case of a new battery bank the alarm is probably due to differences in
initial state-of-charge. If d increases to more than 3%: stop charging and
charge the individual batteries or cells separately first, or reduce charge
current substantially and allow the batteries to equalize over time.
If the problem persists after several charge-discharge cycles:
a) In case of series-parallel connection disconnect the midpoint parallel
connection wiring and measure the individual midpoint voltages during
absorption charging to isolate batteries or cells which need additional
charging.
b) Charge and then test all batteries or cells individually.
In case of an older battery bank which has performed well in the past, the
problem may be due to:
a) Systematic under charge, more frequent charging or equalization
charge needed (flooded deep cycle flat plate or OPzS batteries). Better
and regular charging will solve the problem.
b) One or more faulty cells: proceed as suggested under a) or b).
32