SMA SI 4548-US - Manual (Page 110)

13 Battery Management SMA America, LLC
110 SI4548-6048-US-BE-en-20 Operating Manual
13.5 Charge Control
The Sunny Island uses a three-level charge control, using the IUoU procedure. When operating with
the utility grid, a fourth level, Silent Mode, is optionally available.
The I stands for the constant current phase (I phase). In this phase, the charging is limited by the
maximum defined battery current (parameter "222.01 BatChrgCurMax"), the nominal generator
current (parameter "234.03 GnCurNom"), the nominal grid current (parameter
"232.03 GdCurNom") or the maximum AC charging current of the Sunny Island (parameter
"210.02 InvChrgCurMax"). The respective value reached first is the limiting value. During this phase,
the battery voltage increases as the battery is charged.
Once the battery voltage reaches the predefined value for the second phase Uo (parameters
"222.07 to 222.09", ChrgVtgBoost or ChrgVtgFul or ChrgVtgEqu), the constant voltage charging
(absorption phase) begins.
In this phase, the battery voltage is maintained at a constant level, resulting in a continually decreasing
battery current. The Sunny Island remains in this phase for a defined period of time (parameters
"222.02 to 222.04", AptTmBoost or AptTmFul or AptTmEqu"). For this charging phase, the
Sunny Island automatically selects one of three possible charging methods:
• Boost charge (see Section 13.5.1, page 112)
• Full charge (see Section 13.5.2, page 112)
• Equalizing charge (see Section 13.5.3, page 112)
The remaining charging time (display value "120.04 AptTmRmg") of this phase and the actual
process (display value "120.05 BatChrgOp") can be read on the display.
The following figure shows the relation and the flowchart of the charging phases and charging
processes.