I have a Benimar motorhome which is kept inside a storage facility unattended in the winter . I am disabled so it will not be used during the cold months. It has been suggested I use the EHU to keep the batteries topped up using a timer on the cable for power to run for two hours each day. I am unsure whether I just plug in the cable only or do I have to switch on any of the switches on the power control panel inside the motorhome and leave them on? Advice would be appreciated.