SMA America, LLC
Battery Management
Technical Description
SI5048U-TUS121440
105
13 Battery Management
The battery management of the Sunny Island supports the following three battery types
("221.01 BatTyp" parameter):
The battery capacity (”221.02 BatCpyNom” parameter) is to be entered as the nominal capacity for
a 20 hour discharge (C20). If this information 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 preset for a nominal battery voltage ("221.03 BatVtgNom"
parameter) of 48 V (24 cells for every 2 V) with lead acid batteries (FLA and VRLA) and 45.6 V
(38 cells for every 1.2 V) with nickel cadmium batteries.
13.1 Battery Temperature
The Sunny Island continuously monitors the battery temperature using the battery temperature sensor
provided. At 9°F (5°C) below 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.
When lead acid batteries drop below 14 °F ( − 10 °C) and NiCd batteries drop below − 4 °F
( − 20 °C), a warning is displayed.
The battery temperature is taken into consideration when the charging voltage is calculated (see
section 13.4 ”Charge Control” (page 107)).
FLA
F
looded
L
ead
A
cid: Closed lead acid batteries with liquid electrolyte in all
standard designs available on the market (grid plate, tubular plate, small,
large, etc.).
VRLA
V
alve
R
egulated
L
ead
A
cid: Closed lead acid batteries with immobilized
electrolyte in gel or AGM (Absorbent Glass Mat Separator) in all standard
designs available on the market (grid plate, tubular plate, small, large,
AGM, Gel, etc.).
NiCd
N
ickel
C
admium: Sealed pocket-type plate or fiber plate nickel-cadmium
batteries.
C20
C120/1.18
C20
C10/0.92
C20
C100/1.15
C20
C5/0.81
C20
C20
C20
C1/0.57
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. Up to three individual cells can be
removed and the system can still be further operated.
