Battery management
SMA
Solar Technology AG
126
SI2012_2224-TEN082311
Technical Description
12.4.3 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 a controlled overcharging of the battery bank to ensure that even the weaker cells are fully
recharged. Die 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 ManChrgSel" parameter).
Notice
If the Sunny Island changes to equalization charge after boost charging or full charging
has been running for a specific time, this time is credited toward the equalization charge
completely.
Information
If more than 1 % of the battery's nominal capacity is discharged during an equalization
charge, 50 % of the time elapsed credited toward the next constant voltage phase.
Information
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.
