Recommended float voltage is 2.25V-2.30 V per cell OR 13.5-13.8 V per 12V battery module. Maximum float charging voltage should not exceed 2.3 V per cell OR 13.8V per 12V battery at 27 degree Celsius. Recommended Boost Voltage is 2.37V -2.42V per cell OR 14.2V-14.5V per 12V battery at 27 degree Celsius. For every degree Celsius change in temperature the float voltage should be adjusted by 0.003V per cell or 0.018V per 12V battery. Even a miniscule increase in charging voltage leads to overcharge resulting in inherent water loss in the battery leading to loss of life and performance.
Charging current should be maximum 20% of C20 capacity. i.e. for a 100AH battery maximum charging current should be 20 Amps. As regards minimum charging current, batteries need minimum of 10% of their capacity as charge current in order to achieve 100% charge within the recharge time specified by manufacturers. A lower charging current does not affect battery life, but if the power outages are frequent and the battery does not reach full charge, it leads to reduction of battery life. On the other hand higher charging current beyond 20% results in faster charging but again affects battery life. It’s very important that charging current is between 10 to 20% of battery capacity to obtain maximum battery life
Discharge current should be between 0.5 ~ 3 C20
A normal AGM VRLA battery has a life of 250 cycles of charge/discharge cycles at 90% depth of discharge at normal operating temperature of 25 – 27 degree Celsius. Lower depths of discharge will result in longer cycle life. Please refer to the individual battery technical specifications for exact data. Correct sizing of the battery depending on load and backup time requirement will result in optimal life and performance
Discharge end voltage should be more than or equal to 1.75V per cell or 10.5V for a 12V battery i.e the battery should not be discharged below 1.75V per cell or 10.5V per battery. For high rate discharges from 1C to 3C the end voltage can be reduced up to 1.6V per cell or 9.6V per battery. Refer the battery technical specification table for exact values.
After a discharge, charge the batteries immediately within 24 hours to prevent sulphation of the plates and / or hydration shorts.