Battery Management
SMA America, LLC
106
SI5048U-TUS121440
Technical Description
13.2 Start Options
If the battery is replaced in a system, the battery management system must be restarted and
reconfigured. This can be done using the ”Quick Configuration Guide QCG” (see section
8.2 ”Starting the Quick Configuration Guide (QCG)” (page 66)).
13.3 State of Charge (SOC) and State of Health (SOH)
The Sunny Island has a very precise internal charge level calculation (display value
”120.01 BatSoc”). The operation for calculating the charge level is based on balancing the ampere
hours. This means that all currents flowing in and out of the battery are accumulated and referred to
the nominal capacity. In order to take into consideration faults caused by self-discharge and charging
losses caused by gassing, these losses are already internally extracted. Unlike other operations, no
fixed charging factor must be set.
After full charge has been reached, the charge state value is reset to 90 %, 95 % or 100 %,
depending on the actual state of charge of the battery. If default settings are not changed, a state of
charge of 90 % after boost charge, 95 % after full charge and 100 % after equalization charge is
reached.
Since fully charged states are only rarely achieved, the operation used here can also use the battery
voltage during constant discharge phases with low discharge currents to recalibrate the charge state.
Compared to the ampere-hour balancing method, the operation used here exhibits a high level of
stability over the long term when recalibrated at regular intervals.
Both the ampere-hour balancing method and the recalibration procedure, which is performed via the
voltage, automatically adjust to the connected battery over time (depends on the number of grid
failures).
The estimated charge state error (display value ”120.11 BatSocErr”) will provide you with continuous
information on the accuracy of the battery charge state currently calculated. The average error will
continuously diminish as the adjustment to the actual battery state of charge increasingly improves.
Only when the battery is new its usable capacity corresponds to the capacity specified by the battery
manufacturer. As the battery ages and as a result of frequent insufficient charging, the battery's usable
capacity may decrease considerably on a permanent or only temporary basis.
NOTICE
Destruction of the battery through deep discharge.
If the battery temperature sensor is defective or missing, the Sunny Island continues to run,
assuming a battery temperature of 104 °F (40 °C). This can lead to a deep discharge of
the battery in the long run.
• Observe the corresponding warnings of the Sunny Island.
• Connect the battery temperature sensor.
• Replace the defective battery temperature sensor.
