Equalization Charge; Manual Equalization Charge; Silent Mode - SMA SUNNY ISLAND 4548-US Operating Manual

13 Battery Management

13.5.3 Equalization Charge

A battery bank consists of many individual battery cells connected in series which all behave slightly
different. 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 (parameter
"222.06 CycTmEqu") 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 (parameter "222.12 AutoEquChrgEna",
activated by default) or manually started (parameter "520.01 ChrgSelMan").
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.

13.5.4 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.
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.

13.5.5 Silent Mode

In addition to the float charge, the silent mode can only be used (parameter "224.01 SilentEna")
when operating on the utility grid.
The main purpose of the silent mode is to save energy by switching from charge mode to standby
mode in battery-backup systems where the Sunny Island is predominantly in float charge.
The silent mode is activated after the time set for float charge (parameter "224.02 SilentTmFlo") has
expired. The Sunny Island remains in silent mode for a fixed time (parameter "224.03 SilentTmMax")
or until the battery voltage per cell is 0.14 V lower than the set voltage (parameter
114 SI4548-6048-US-BE-en-21
SMA Solar Technology America LLC
Operating Manual