
With the charger in switched off mode, connect the battery, ensuring correct polarity between the
power plugs, that is positive to positive, negative to negative – (refer figure 3). Now, switch on the
charger. During charging the temperature of the electrolyte rises by about 10°C, so charging should
only begin if the electrolyte temperature is below 45°C so that it does not overshoot the maximum
limit of 55 deg C.
The minimum electrolyte temperature of batteries should be at least +10°C before charging, otherwise
full charge will not be achieved. Use the following charging parameters:
of C5 Ah rat-
ing of the
battery
the C5 Ah rat-
ing of the bat-
tery
A charge is finished when the specific gravity of the electrolyte and the battery voltage remain con-
stant for two hours (measured at 30 minutes interval).
The specific gravity of the electrolyte depends on temperature (see 2.5). The final charging voltage de-
pends on temperature, too. The correction factor is 0,003V/C. Example: 2,65V at 40°C equals 2,68V at
30°C.
Towards the end of the charging, check level of the electrolyte (refer figure -1) and top up with water
of purity as given in this manual, till the level reaches the bottom of the plug basket (refer figure 1).
Allow the battery to be on charge for at least an hour after adding the water so that the water mixes
up with the acid and is uniform along the height of the cell.
2.3 Equalising charge
Equalising charge is used to safeguard the life of the battery and to maintain its performance. They are
necessary, if the acid density of the cells varies by more than 0,01kg/l and the charging voltages vary
by more than 0,05V from average. It is advised after repeated deep discharges, repeated incomplete
recharges. Equalising charges are carried out following normal full charging. The charging current must
not exceed 5% of the C5 Ah. The equalising charge is completed, if the acid density and voltage of all
single cells do not increase by more than 0,005kg/l or 10mV within 2 hours. This takes normally 8-
12h. In case of sulphated batteries, a charge with 3% of C5 Ah over 1-2 days may be required.
Make sure that the temperature does not exceed 55 deg C. Interrupt equalising charge, if necessary if
the temperature goes above 55 deg C. At the end, check level of the electrolyte (refer figure 1) and
top up with water quality as mentioned earlier. Clean and dry the surface of the battery at the end of
topping up.
Use Auto-fill system to take care of spillage of acid while topping up.
Record the cell voltages, specific gravity and temperature after every equalisation charge.
This has to be done for all cells in the battery. Warranty will be void in case this data is not
available at the time of warranty claim.
2.4 Temperature
An electrolyte temperature of 30°C is specified as the nominal temperature. Higher temperatures
shorten the life of the battery and lower temperatures reduce the capacity available. Difference of 10
deg C in the average operating temperature affects the life performance by 50%.
55°C is the maximum temperature limit for traction battery and is not the temperature for
continuous operation.