SMA Solar Technology AG Battery management
Technical Description SI5048-TEN093630 97
13.4.3 Equalization Charge
A battery bank consists of many individual battery cells connected in series which all behave slightly
differently. Over time, this results in different charge levels in the individual cells. This can lead to
premature failure, initially of individual cells, and finally to failure of the entire bank.
The Sunny Island can perform an equalization charge automatically every 180 days
("222.06 CycTmEqu" parameter) or every 30 nominal charge throughputs. During this process, it
performs controlled overcharging of the battery bank to ensure that even the weaker cells are fully
recharged. Equalization charging extends the battery service life by up to 50 %. The automatic
equalization charging function can also be deactivated ("222.12 AutoEquChrgEna" parameter,
activated by default) or manually started ("520.01 ChrgSelMan" parameter).
External charging device
If an external charger or charge controller is connected to the battery and the criteria for
a full charge are fulfilled due to external charging, the Sunny Island treats this as if it had
performed the full charge itself.
Procedures Parallel to the Full Charge
Any parallel procedures causing the generator to stop during the full charging process are
not taken into account until the charging process is completed.
Change to an Equalization Charge
If the Sunny Island changes to equalization charge after a specific time of boost charging
or full charging has elapsed, these times are completely considered for the equalization
charge.
More than 1 % of the nominal capacity of the battery will be discharged
If more than 1 % of the battery's nominal capacity is discharged during an equalization
charge, 50 % of the time elapsed is considered for the next constant voltage phase.
External charging device
If an external charger or charge controller is connected to the battery and the criteria for
a full charge are fulfilled due to external charging, the Sunny Island treats this as if it had
performed the full charge itself.
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