SMA SI 3324 - Manual (Page 37)

SMA Technologie AG Battery Management
User Manual SI3324/4248-14:FE2406 Page 37
For the second charging level V
0
, the constant voltage charging (absorption phase)
for a limited period of time, the Sunny Island 3324/4248 automatically chooses
between three different voltages and charging times. These are the boost charge, full
charge and equalizing charge. The following figure shows a process diagram of the
charging process.
The Sunny Island 3324/4248 most often chooses the boost charge in order to bring
the batteries to a reasonable level in a short period of time. This process is optimized
to keep the generator run times as short as possible.
The Sunny Island 3324/4248 initiates a full charge every 14 days or after every
eight charging throughputs, with the aim of fully recharging the batteries to remove
any negative effects caused by insufficient charging. Various studies have shown that
regular full charging every two to four weeks can double the battery service life in
off-grid systems.
A battery bank consists of many series-connected individual battery cells (2 V each),
each of which having a slightly different behavior. Over time, this results in different
charge levels of the individual cells. This can lead to premature failure of first single
cells and then failure of the entire bank.
Boost Charge
V = VchargeBoost
Full Charge
V = VchargeFull
Equaliziation
V = VchargeEqual
Floating Charge
V = VchargeFloat
Silent Mode
Bms Silent Request = on
TcycleEquals days or 30
charging throughputs
TcycleFull days or
8 charging throughputs
V > VchargeFull
for TabsorbFull
V > VchargeEqual
for TabsorbEqual
TcycleEquals days or 16
charging throughputs