Floating charge voltage must be kept at a value high enough to compensate for the battery’s self-discharge to keep the battery in a fully charged condition at all times but low enough to minimize life deterioration due to possible overcharge.

The optimum charge voltage for VRLA Battery is 2.23V per cell (or other by battery brand) under normal temperature condition (25˚C (77˚F)).

The VRLA Battery requires no equalizing charge. This is because of its low self-discharge rate resulting in a minimal variation among the cells in a battery bank and float charge at sufficient voltage to maintain it in a fully charged condition.

Recovery charge after the battery has been discharged can be carried out at the float charge voltage of 2.23V/cell. (VRLA)

The charging time to fully a discharged battery by constant current and constant voltage of 0.1 CA and 2.23V respectively at 25˚C will put back more than 100% of the previous discharge in 24 hours.

Since the battery does not restrict the size of initial charge current, making it larger will shorten the time for a charge of more than 100%.

At the recommended operating temperature of 15˚C - 25˚C and under optimum float conditions, the service life is expected to comply by manufacturer designed. The length of float charge life is influenced by discharge frequency, discharge depth, float charge voltage and service environment.

Corrosion speed will be accelerated as the temperature rises, making the life shortened. Also the higher the charge current, the faster the corrosion, therefor it is necessary to float-charge the battery at the proper voltage. The float charge voltage should always be set at 2.23V per cell, using a battery charger with voltage accuracy of±2% or better. (example for VRLA battery)