According to the VARTA Instruction Manual
a.) Standard charging method:
IU charging characteristics with I = 10 % of nominal capacity.
The maximum charging voltage should be 14.1 – 14.4 V.
b.) Permanent charge:
Limit charging voltage to 13.38 V (2.23 V/cell).
If charging voltage is below 13.2 V (2.20 V/cell) an additional charge with
higher voltage is necessary in regular intervals to ensure the battery
In alternative use charger
with IUoU charging characteristics with I = 10 %
of nominal capacity.
c.) Charging to avoid acid stratification
Use IU charging characteristics with a higher charging voltage (up to 16 V).
This „overcharge“ should only be used for short time period to avoid
- The OCV (open-circuit voltage) after charge should be 12.7 – 12.8 V.
- For every 0.1 V difference to 12.7/12.8 V the battery should be charged for