SMA Sunny Island 5048 - 13 Battery Management; Battery Temperature

SMA Solar Technology AG Battery Management
Technical Description SI5048-TB-TEN110340 97
13 Battery Management
The battery management of the Sunny Island supports the following three battery types
("221.01 BatTyp" parameter):
•FLA
•VRLA
•NiCd
The battery capacity ("221.02 BatCpyNom" parameter) is to be entered as the nominal capacity for
a ten hour discharge (C10). If this is not available from the battery manufacturer's data sheet, it can
be calculated from the data for different discharge times (120 h, 100 h, 20 h, 5 h, 1 h) in the
following manner:
The Sunny Island is designed and set by default (parameter "221.03 BatVtgNom") for a nominal
battery voltage:
• 48 V (24 cells at 2 V each) in the case of lead batteries (FLA and VRLA)
• 45.6 V (38 cells at 1.2 V each) in the case of Nickel-Cadmium batteries
13.1 Battery Temperature
The Sunny Island continuously monitors the battery temperature using the battery temperature sensor
provided. At 5 °C under the maximal temperature allowed (set using the parameter
"221.04 BatTmpMax"), a warning is displayed. If the maximum value for the battery temperature is
exceeded, the Sunny Island switches off.
A warning is output if the value for lead-acid batteries falls below –10 °C for below –20 °C for NiCd
batteries.
The battery temperature is taken into consideration when the charging voltage is calculated (see
section 13.4”Charge Control” (page99)).
C10 C120/1.28 C10 C10
C10 C100/1.25 C10 C5/0.88
C10 C20/1.09 C10 C1/0.61
Failure of individual battery cells
If individual battery cells fail over several years of continuous operation, the nominal
voltage can be set in the range from 42 V to 48 V (see 8.2”Starting the Quick
Configuration Guide (QCG)” (page57)). Up to three individual cells can be removed and
the system can still be further operated.