Start Options; State Of Charge/Soc And Soh - SMA Sunny Island 5048 Installation Instructions Manual

Battery Management
If the battery temperature sensor is not connected or a short circuit or a cable
break on the sensor is detected, a warning message is generated; however, the
Sunny Island 5048 continues to operate at a fixed set battery temperature of
40 °C. Over time this leads to insufficient battery charging.

13.2 Start Options

If the battery or individual cells are removed from the battery bank in a system, the
battery management must be restarted and configured. This can be done using the
"Quick Configuration Guide QCG" (see section 8.2 "Starting the Quick Configuration
Guide (QCG)" (Page 57)).

13.3 State of Charge/SOC and SOH

The Sunny Island 5048 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. That means that all currents that flow in and out of the
battery are added together and based on 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 omitted. Unlike other operations, no fixed charging
factor must be set.
If you wish to connect other loads or generators to the battery, whose
currents are not detected by Sunny Island 5048, you must connect an
external battery current sensor in order for the charge state to be detected
correctly. The external battery current sensor also improves the precision
of the state of charge (SOC) and the state of health (SOH).
When the fully charged state is reached, the charge state value is set back to 90 %,
95 % or 100 %, depending on how full the battery was actually charged. If the default
settings are not changed, a charge state of 90 % is normally reached after a boost
charge, a charge state of 95 % is normally reached after a full charge and a charge
state of 100 % is normally reached after an equalization charge.
Since fully charged states are only rarely achieved in specific offgrid applications, the
operation used here can also utilize the battery voltage during constant discharge
phases with low discharge currents to recalibrate the charge state. In most applications,
these phases are reached at night. 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
(approx. 4 to 8 weeks). Since many of the battery types on the market today exhibit
extremely varied behavior, no values can be determined. The best option is to make
adjustments to the respective battery according to the procedures described above.
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Technical Description