OHM uses Li-Ion batteries that have a no “memory effect.” You can charge the battery at any time regardless of its state of charge. Please note that this does not affect the overall performance of your system. When not in use for a longer period of time, batteries should be stored fully charged and be fully recharged at least once every 3 months. Please also follow the instructions in the manual regarding the proper storage of batteries. In any case, a deep discharge of the battery has to be avoided.