Re: Wiring a 12V system in a trailer

["Neil" <neil@sherry02.freeserve.co.uk>]

Here in the UK the standard for this sort of thing is called a 'split charge
relay', which only connects the aux. battery to the tow vehicle's electrical
system if the vehicle voltage is above something like 13 volts. So if the
alternator is charging, the aux. battery will be charged, and soon after the
engine stops the aux. battery will be disconnected. It also ensures that the
vehicle's own battery is reasonably charged before the relay trips.

Neil