On a quick trip back to the UK I was looking for a way to reliably and safely install a charging system to run a second battery (powering only fridge and low powered gizmos - no winch). My criteria were that the system must not involve modifying the main vehicle cranking system, must be fail safe and as simple as possible. Previous home made systems have included split charge diodes and one using a really simple second battery joined with a massive switch coming through the seat box in a defender - but that was really designed to help with winching. This system is simply to charge (as best as possible) a big second battery for fridge, small inverter, camp lights etc... After a lot of web trawling I came up with a sterling battery to battery four stage charger. This apparently simply gets wired in between the cranking and auxilliary battery and is able to keep the cranking one charged but also fool the alternator into keeping the second battery well charged etc. Now I haven't yet installed it but the thing seems solidly built - they seem to be directed at marine installations so I guess should be fairly reliable. It also can accept solar panel input so I can wire up a big solar panel I found in a workshop. The unit also claims to be completely fail safe in that if it fails the aux battery cannot draw current from the cranking battery. Now to install it! Just wondered if anyone has tried such a device? Will let you know how it performs, but it 'looks' like a possible good solution to the good old split charging issue, as well as having a few (like plenty) LEDs to keep me happy!
Gil