Camper-Caravan Comfort and safety in the open air On-board comfort today is increasingly dependent on energy, so it is of fundamental importance to have batteries at peak performance. With simple photovoltaic modules and a battery the game is done, but beware! The efficacy of this plant depends on the heart and Brain of the system: the charge regulator. The WRM15 dualB is an MPPT charge controller for photovoltaic applications that can automatically manage the charge of two batteries, one primary and one secondary. It also features a Bluetooth connection for APP control on Android and iOS mobile devices.