earthandgnar said:
Summary:: looking for help designing my simple camper van electrical system, as I know very little about electrical circuits. 4 days of research and this is what I came up with (attached) Thanks!
I am looking for some advice planning the electrical system for my camper van.
In the past, I had a VW camper with a 'Zig' Unit that, reputedly, automatically took care of charging the leisure battery whenever possible. ('Split charger') If that battery started to sag, iirc, you could use the start battery for domestic use at your own risk. I must say, it just
worked but the 12V loads were very small, being a few lamps and a water pump. The fridge was a two way job (gas / electric and horribly inefficient)
This link has a number of comments of the (dated) Zig System. Opinions are luke warm about Zig.
I've been where you are, only the later application was a sailing cruiser with inboard engine. You will probably have looked at Caravan systems and you would be well advised to look at 12V systems for boats too. You can pay an absolute fortune for turnkey systems that have all the bells and whistles. The one essential feature is that the Start / vehicle battery should be isolated from the domestic battery except when they are both charging AND a switch panel with separate switches and fuses for all the different appliances. Things always fail in the dark and you need to be able to fault find quickly and no in the pitch black. When I took over the boat, there was a A/B/A+B/ Off switch and that was all. It worked fine as long as I remembered to make sure it was all Off when I left the boat. It also meant that the either battery could be used to start the engine. (Fine if you were planning to do some lengthy motoring that day. Mine was a motor sailor and I used the motor as little as possible.
Split Charger: At one time, people used two diodes to ensure that neither battery could discharge into the other one but that meant there was a 0.5V drop in the charging circuit and the regulator was not operating ideally. Remote voltage sensing would take care of that but it's another wire needed (plus some knowhow, plus an appropriate alternator).
VSR: I finally chose to put in a Voltage Sensing Relay (a range of prices for these so shopped around) which did the thinking for me. It defaults to charging the start battery and switches in the leisure battery when the start battery is fully charged. It disconnects if the volts drop too far. I kept the A/B/AB switch as belt and braces and as the ultimate circuit breaker but the system worked fine and I never had a problem, despite using an electric (compressor) fridge and an auto helm (not a lot of use though).
I had a very inadequate Wind Turbine but, nowadays, I would have chosen some PV panels which do a good job as long as you use twice the area that you are told is necessary. I guess covering the roof with low profile panels wouldn't affect the drag factor too much. But the worse mpg could probably pay for an hour of static running of the engine if you need a day or two at a site, static.
My main advice is to do nothing yet, until you have read all those links above and also read the Boating Mag articles. (Dozens available)
If you do this yourself then make sure to use good connectors (not just chocolate block), thick cable, heat shrink sleeving and trunking. (And several different colours of cable!)
