I`ve always run the (decent Dometic) fridge from the main battery with a relay which supplies the fridge with power ONLY when the engine is running . Never had any issues running this set-up ... Last year i fitted a leisure battery purely to run a Propex . I`m finding the leisure battery is occasionally not being charged sufficiently to fire up the propex . My thoughts are along the lines of main battery is drawing it`s charge and the 12v fridge charge meaning the split charger isn`t kicking over enough to charge the leisure battery ?? Should the 12v fridge supply be taken from the leisure battery - i can`t seem to find a diagram that shows a definitive answer .... Over to the electrickery gurus amongst the LB massive - innit ....
It's probably taking 9 - 10 Amps, so the LB won't be getting much charge. No different if you wire it to the LB it'll still be robbing the Amps.
Surely the alternator is kicking out zillions of amps when running so 9 or 10 amps to the fridge won't affect the charging that much will it?
Though my fridge is 12v all the time and hooked up to the leisure battery, I disconnected the split charge as I suspected once the leisure battery was depleted, the main battery never really got much charge. I have solar and hookup charging for leisure and leave the alternator to just do the starter, as nature intended.
That was my reasoning , but electrickery isn`t my thing to be honest .... I refuse to go down the hook-up route as `er indoors will just fill the van with `essentials`
I think your problem is that the main battery never got very discharged, so driving after starting engine recharged it and ran fridge no probs. It was a regular car setup with a fridge on the alternator. When you discharge your leisure battery while camping, you take more from it than you can put back driving home so you need to put it on a mains charge for at least 8 hours, overnight is better. I used to have to take the battery out to do that and got through a couple of batteries very quickly by forgetting/ not bothering. A solar panel is a good answer unless your van lives in the shade where you park it. Built in charger for hookup once every few days or your last night before heading home?
If you are using a self switching relay this is part of the problem and why I don't like them on our old vans The alternator only puts out enough to satisfy the load so as the main battery fills up the alternators output drops With a self switching relay it only switches when the main battery reaches a set voltage With the fridge taking a large load from the main battery it will mean the relay may not switch or not for some time A normal relay puts both batteries together so the alternator is under max load and so charges both battery's in the least time If you go for it you can get proper intelligent 12 V to 12 V chargers that varies the load on the alternator to give maximum charge
The alternator is very unlikely to put out 55amps and if so for a short time before it tales off. Best way i can think to describe it is the flat battery is a sponge, the alternator is a supply of water and the water is amps put the dry sponge in the water and it will suck up the water quickly but as it gets wet the amount of water it takes on slows down and never gets fully saturated
That still leaves 45 amps to operate the spark plugs and charge the battery. My Ctek can charge the battery with 7 amps. What happens to the rest of the available current?
Rated output is at high revs so in normal driving you won't see that output and the fridge draw will be significant. @matty's post is relevant too, the fridge draw keeping the main battery from looking like it's fully charged, so the split charge not kicking in.
Fair point. I think my split charge relay kicks in when there is a voltage on the trigger wire so both batteries and the fridge are all in parallel to the alternator.
The split charger is the `intelligent` voltage sensing type (no trigger wire) so logically the draw from the fridge could confuse it into thinking it needs to charge the van battery although it should be banging amps into the leisure side of things ?? That seems logical Does anyone actually have a fridge connected to the leisure Battery to chill from 12v ONLY when running ?? @zedders - the van is kept in a covered parking bay down the road , no electric and the parking is covered so solar isn`t really an option . I`ve got the battery charging at the moment in the kitchen - she`s doing a sterling job getting dinner ready around all the wires
Leisure batteries are expendable and not expensive, but when they loose capacity, which they do, it's inconvenient. However funky you get with the split chargers, a weekend away needs 8 hours charging min, or you are accelerating your batteries demise.
@Lasty, I predict you've done what I any many many others have done and gradually, or not not so gradually reduced your capacity by inadequate charging. Batteries are barstwards.
