13 Battery Management
SMA America, LLC
112
SI4548_6048-US-TB_en-13
Technical description
13.4.3 Equalization Charge
A battery storage system consists of many individual battery cells connected in series which all behave
slightly different. Over time, this results in different states of charge 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 equalization
charge, it performs controlled overcharging of the battery storage system to ensure that even the
weaker cells are fully recharged. Equalization charging extends the battery 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).
13.4.4 Manual Equalization Charge
The parameter "520.01 ChrgSelMan" activates the manual equalization charge on the Sunny Island.
If a generator is connected to the system, it is automatically started and stopped once the equalization
charge 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 battery capacity is discharged
If more than 1% of the nominal battery 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 an
equalization charge are fulfilled due to external charging, the Sunny Island treats this as if it
had performed the equalization charge itself.
Carrying out the equalization charge
An equalization charge should be performed at least once a year. After long periods of time
without charging, e. g. in the case of plants which are only operated seasonally, equalization
charges should always be performed manually at the end or at the beginning of the season.
Summary of Contents for Sunny Island 4548-US
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