According to at least one embodiment, an uninterruptible power supply (UPS) is provided. The UPS includes a first input configured to couple to a primary power source to receive primary power; a power bus coupled to a plurality of battery modules to receive back-up power; an output operatively coupled to the first input and the power bus to selectively provide, from at least one of the primary power source and the plurality of battery modules, uninterruptible power to a load; and a charge bus coupled to the plurality of battery modules to provide power to the plurality of battery modules. The UPS is configured to detect at least one battery module of the plurality of battery modules has reached a charging threshold and discontinue charging of the at least one battery module in response to detecting the at least one battery module has reached the charging threshold.