Hi, my new old caravan has no charger, the battery runs everything in the caravan except for two 240 volt sockets - now my question is simple: I want to buy a charger to charge the battery which will run from one of the sockets which in turn will be plugged into the site hookup... now... whilst it is charging onsite, will I be able to still use the 12 volt appliances, or will the fact the battery is on charge damage them? I hope that makes sense...
Or, would it be better to use a charger with a built in transformer, so that whilst the battery is charging the 12 volts will run off the 240 via the transformer...
I've always bought my chargers on eBay - used but ok and caravan battery chargers which means you'll be getting a proper charge and you'll be able to run your 12 volt equipment without problems as well.
To charge a Lead-Acid battery you need 13.8 to 14.2 VDC. By using a charger you can use all normal lights but not all electronics, e.g Radio, Laptop converter for 230VAC, and so on. Mostly all of the battery chargers are just for that purpose, charging only. The output of such chargers is not regulated or smoothed so a large amount of 'Rest AC' is present at the output. Also the output voltages rise up to 20V when fully charged. Use only a switched mode power supply unit of the same amps as the fridge, 6 to 10 amps. If you want to see just how to wire all this into your van then please visit my web site. Good luck anyway.
When our KT12 charger failed last year in our old 1991 Swift Challenger I bought a smart battery charger from Halfords. I hard wired it into the incoming fused mains and direct to the battery with a toggle switch on the seat base so that we can 'isolate' charge to the battery from inside the van (i.e. same as charger being plugged in but not connected to battery).
Works really well on hookup and never had to use the toggle switch (apart from when van not being used to stop current drain). Keeps battery charged and runs appliances and of course drops into 'maintenance' mode when battery voltage shows full charge, and goes back to full charge mode when battery indicator approaches bottom of green section.
Battery indicator gets towards top of green area at the 'maintenance' stage but never off the scale so presume that its not giving higher than safe voltages to appliances.