SMA Solar Technology AG
Battery Management
Technical Description
SBU2200-TEN083320
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The battery's state of health (display value "342.01 Soh") is a percentage measurement for the
present useable capacity relative to the nominal capacity. 100 % means that the entire nominal
capacity can still be utilized. At 50 %, only half of the original nominal battery capacity can be
utilized. The battery's state of health is also calculated using a self-adapting method that requires
several charging cycles before it can produce accurate and precise values.
The present capacity for the Sunny Backup 2200 is automatically adjusted downwards for
temperatures <20 °C, since the useful capacity of batteries is significantly reduced in temperatures
below the nominal temperature. For all lead acid batteries, the nominal capacity is amended by a
fixed factor of –1 %/°C. For NiCd batteries a factor of –0.75 %/°C is used.
16.4 Charge Control
The Sunny Backup 2200 performs charge control in 3 phases using the IUoU process. When the
device operates with the public grid, there is also an optional fourth phase called silent mode.
The I stands for the constant voltage phase (I phase). In this phase, the charging process is limited by
the maximum specified battery current ("222.01 BatChrgCurMax" parameter), the nominal grid
current ("232.03 GdCurNom" parameter) or the maximum AC charging current of the Sunny Backup
2200 ("210.02 InvChrgCurMax" parameter). 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
("222.07 — 222.09", ChrgVtgBoost or ChrgVtgFul or ChrgVtgEqu parameters), 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 Backup 2200 remains in this
phase for the defined period of time ("222.01 — 222.03", AptTmBoost or AptTmFul or AptTmEqu"
parameters).
