SMA SI 4548-US - Manual (Page 112)

13 Battery Management SMA America, LLC
112 SI4548-6048-US-BE-en-20 Operating Manual
13.5.1 Boost Charge
The boost charge is the most common charging process of the Sunny Island. The boost charge ensures
a high generator workload through a high charging voltage over a short period of time. With liquid
FLA lead-acid batteries, this charge process should be used for gassing and thus compensating the
electrolytes. The boost charge process can charge the battery up to approx. 85% to 90%.
13.5.2 Full Charge
Every 14 days or after eight nominal charge throughputs, the Sunny Island automatically initiates a
full charge (parameter "222.05 CycTmFul").
The objective is to recharge the battery to a state of charge of at least 95% and rectify possible effects
caused by an insufficient charge. Regular full charging approximately every two to four weeks can
double the battery life.
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
Nominal charge throughput
A nominal charge throughput is reached when the sum of the discharge currents corresponds
to the nominal capacity of the battery.
Example: The battery has a nominal capacity of 100 Ah. A nominal charge throughput is
reached when the battery has been discharged ten times for one hour by 10 A.
Change to full charge
If the Sunny Island changes to full charge after a specific time of boost charge has elapsed, the
entire time of boost charge elapsed is considered for full charge.
More than 1% of the nominal battery capacity is discharged
If more than 1% of the nominal battery capacity is discharged during a full charge, 50% of the
time elapsed is considered for the next constant voltage phase.
External charging device
If an external charging device 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.
Parallel procedures for full charge
Any parallel procedures causing the generator to stop during full charge are not taken into
account until the charging process is completed.