SMA Sunny Island 2012 Technical Description page 123

SMA Solar Technology AG
Battery management
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
("222.02 — 222.03", AptTmBoost or AptTmFul or AptTmEqu" parameters). For this charging phase,
the Sunny Island automatically selects one of three possible charging methods (boost, full,
equalizing) which are described in detail in sections 12.4.1 "Boost Charge" (Page 124) to 12.4.3
"Equalization Charge" (Page 126). The remaining charging time (display value "120.04
AptTmRmg") of this phase and the current process (display value "120.05 BatChrgOp") can be
read on the display.
The following figure displays the relationship and the process diagram of the charging phases and
charging processes.
Once this constant voltage phase is finished, the Sunny Island switches to float charge which again
carries out constant voltage charging but at a greatly reduced charging voltage
("222.10 ChrgVtgFlo" parameter). The purpose of the float charge is to keep the battery in a fully
charged state without causing premature aging through overcharging. The Sunny Island remains in
this phase until either more than 30 % of the nominal capacity has been used (all discharges are
added up) or the state of charge is below 70 %. When the Sunny Island is operating on the public
grid, it can also switch from the float charge into silent mode.
Technical Description SI2012_2224-TEN082311 123