SMA SI 4548-US - Manual (Page 115)

SMA America, LLC 13 Battery Management
Operating Manual SI4548-6048-US-BE-en-20 115
Battery-preservation mode levels 1 and 2 are automatically quit as soon as an external voltage source
(grid reconnection/generator start) is present at the AC2 terminal. For exiting these levels, a hysteresis
of 5% of the state of charge is provided.
Only battery-preservation mode of level 3 is not automatically quit if an external voltage
source (grid reconnection/generator start) is present.
The battery-preservation mode can be quit by manually starting the Sunny Island. If, within ten minutes
(see above), charging current is detected, the Sunny Island continues to operate; otherwise, it
switches off again.
13.7 Battery Diagnosis
The "320# Battery Diagnosis" menu displays several values that provide information on the past
operational behavior of the battery. These values are helpful in checking the efficiency of the set
parameters and in viewing the typical operating conditions of the battery (see Section 19.3
"Diagnosis (300#)", page 192).
13.8 Battery Lead Resistance
In menu "221# Battery Property", you can specify the battery lead resistance (BatWirRes). The
resistance is the ohmic resistance from the battery to the input of the master device. The default value
of the parameter "221.06 BatWirRes" is 0 m Ω .
The resistance is made up of the resistance of cable 1 and fuse and resistance of cable 2:
R = R (cable 1) + R (fuse 1) + R (cable 2)
Saving potential due to battery-preservation mode
In inverter operation, the Sunny Island draws 25 W of the battery power. If the device is in
standby mode, only the on-board power supply, which requires approx. 4 W, is supplied. This
results in a savings of 21 W.
Using the conditions described in level 1 of the battery-preservation mode and assuming an
operation time from 6 a.m. to 10 p.m., this results in 336 Wh/day. This in turn corresponds to
7 Ah at 48 V and thus 210 Ah per month (30 days).