I have got a Autotrail Apache 700 ? How long do you leave fresh water in your tank for ? and is it best to drain it off, before replenishing ? I have a drop down DVD player at the cab entrance, can you tell me how to switch it on ? How long does it take to charge a leisure battery ? (flattened mine left the switches on ooops ) It would be better if I could meet up with someone and pick their brains ?