SUNNY ISLAND 5048 - Technical Description - Wind & Sun Ltd.

Battery Management SMA Solar Technology AG
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 13.4.1 ”Boost Charge” (page 101) to 13.4.3 ”Equalization
Charge” (page 102). 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 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 power
distribution grid, it can also switch from float charge into silent mode.
Changing the charging voltage
The charging voltage does not change erratically. Instead, it slowly changes to the new
setpoint at a rate of approximately 0.5mV/cell*s when switching from constant voltage
charging to float charge. This also happens if the setpoint is set manually.
100 SI5048-TB-TEN110340 Technical Description