Maintenance
Manual_Grid_Power_FNC_en_V3_0
49
Note - valid for grid|power FNC
®
VR cells
Remove a VR plug carefully. It is recommended to use the HOPPECKE plug opener (Mat. No.
4142500125)
Alternatively use a small, slot screwdriver. Grab the plug with your hand and slowly twist and
vertically pull out the plug from the cell opening.
Wear personal protective equipment because grid|power FNC
®
VR cells operate under pressure.
Removing a VR plug can release electrolyte spray.
2. Remove the insulation profiles.
3. Measure the voltages of the individual cells using a digital multimeter and note the
values in the maintenance log. The open circuit voltage of a fully charged, non-defective
cell at 20 °C is ≥1.3 V.
Note
The individual cell voltages should not vary by more than ± 50 mV from the mean of all cell
voltages.
If the open circuit voltage of a cell is < 1.2 V, contact HOPPECKE service.
4. It is recommended to insert a gas venting tube on each grid|power FNC
®
cell,
(HOPPECKE material number: 4143180100). This reduces the contamination by
electrolyte.
5. Discharge the battery system by using a charging/discharging device with nominal
current I
5
, until the voltage of the battery system has dropped to 1.0 V per cell in the
arithmetic middle (e.g., battery system with 54 cells -> 54 V).
6. Allow the battery system to rest open circuit for at least 8 hours, preferably overnight.
7. Measure the temperature of the battery system by inserting a suitable glass
thermometer.
The cell to be measured should be installed in the centre of the system, in order to
capture the warmest possible spot of the system. Record the measured value.
