Victron energy BMV-700 Manuel page 34

This same percentage can be applied to a 12 V battery bank with a 6 V
midpoint.
In case of a 48 V battery bank consisting of 12 V 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 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:
c) Systematic under charge, more frequent charging needed, or
equalization charge needed (flooded deep cycle flat plate or OPzS
batteries). Better and regular charging will solve the problem.
d) One or more faulty cells: proceed as suggested under a) or b).
5.2.4 What to do in case of an alarm during discharging
The individual batteries or cells of a battery bank are not identical, and
when fully discharging a battery bank the voltage of some cells will start
dropping earlier than others. The midpoint alarm will therefore nearly
always trip at the end of a deep discharge.
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