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6.2.3 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.
6.2.4 WHAT TO DO IN CASE OF AN ALARM DURING CHARGING
In case of a new battery bank the alarm is probably due to dierences in initial state-of-charge. If deviation increases
to more than 3%: stop charging and charge the individual batteries or cells separately rst, 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 (ooded deep cycle at 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).
6.2.5 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.
If the midpoint alarm trips much earlier (and does not trip during charging), some batteries or cells may have lost
capacity or may have developed a higher internal resistance than others. The battery bank may have reached the
end of service life, or one of more cells or batteries have developed a fault:
a) In case of series-parallel connection, disconnect the midpoint parallel connection wiring and measure the individual
midpoint voltages during discharging to isolate faulty batteries or cells.
b) Charge and then test all batteries or cells individually
MORE ABOUT PEUKERT’S
FORMULA & MIDPOINT MONITORING
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