It is advisable to periodically do checks and maintenance.
Measure the total voltage of the batteries during trickle charge (or float charge). If the charge equipment provides a irregular (incorrect) read-out, be sure to investigate the reason behind any deviations from the specified voltage range.
When the total voltage is lower than the specified voltage, the batteries may lose their capacity by lack of sufficient charge. And when the total voltage is higher than the specified voltage, the batteries may lose their capacity by damage due to overcharge, and may suffer from “thermal runaway”.
Check the batteries for any sign of irregularities in appearance. If any damage such as a crack and deformation, or electrolyte leakage is found on the case, cover, etc., the batteries must be replaced with a new one. Also, clean the batteries if these are found dirty due to dirt and dust. If the batteries with irregular appearance continue to be used, decrease of capacity, leakage of electricity, smoke and /or fire may occur.