The Pentax cameras have a soldered chargeable battery (i.e. accumulator), this is used to keep the data when changing the accumulator. unfortunately in the user manuals you are advised to store your camera without inserted accumulator, this leads to deep power states in soldered battery, if this happens frequently it damages the soldered battery like any other rechargeable battery, deep power states are deadly for rechargeable cells, and they are hardly to revive. So the advise is to use your camera reguarly (at least every few weeks/months) store it with an loaded main battery, and check the state from time to time and recharge the main battery (its no problem to have the main battery out of cam for the charging time, if this allready leads to a problem the internal cell is done, and you have to set date and time and settings everytime you chang the main battery). Use the internal battery as it is intended, keeping the data while you took out the main battery for charging)