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What type of Isolation Switch?


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Hi all -


I've now fitted a second leisure battery right next to the original one on our old-dog motorhome, without blowing myself up.......


There is one other thing I'd also like to fit: an isolation switch in-line to the positive 12 volt wires eminating from these batteries and leading to all the 12 volt equipment inside the Motorhome.


The idea is to ensure that we don't inadvertently leave anything on in the MH and thus gradually drain the leisure batteries when we park it up for a week or two.


There was already a similar setup on our previous MH, which although obviously "home made" by the previous owner, worked brilliantly.





So my question to all you electrickery types is: what type of switch should it be, and can you recommend an exact swictch from any on-line supplier that I could order over the interent (regulars will know that we live in Spain, so we generally buy such stuff via internet)?




There are two, 12 volt red cables eminating from the leisure batteries, and I want to combine them at the isolation switch....both are quite stout, so the switch needs to have quite large contact holes that I can scew these two cables into on each side of the actual switch.

I guess the actual switch mechanism also needs to be pretty heavy-duty.

It does not have to be pretty, it just needs to be big and butch.




Another thought.............Anyone got such a switch (either surface mount, or that I could mount through a drilled hole in the battery compartment fascia) knocking around in their garage, pining for a nice new home in the sunshine in exchange for postage and a contribution to your alcohol-buying kitty??????????


Any advice appreciated mis amigos. :-D

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Thanks Tony - I guess that's the sort of thing.


I've had a trawl around the internet and fleabay in particular this afternoon......the sort of isolator switch with the red plastic removeable key is the type of thing I had in mind.

They seem to be in the 7 or 7 quid price range generally, so not expensive.


Just wanna see what any experts here might say about them/other types before I dive in and order summat from somewhere.....

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Both of my French leisure-vehicle accessory catalogues carry adverts for battery isolation switches, with the price varying according to the Amperage the switch is designed to handle. So you may well be able to source suitable switches locally in Spain without having to resort to buying on-line. Any company specialising in motorsport-related vehicle-accessories is also likely to offer such switches.


An alternative might be to insert removable fuses in the cables close to the batteries. This would provide circuit protection as well as allowing you to isolate the batteries when your motorhome is not being used.

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Geoff Cole - 2009-03-26 9:05 AM



I fitted a durite battery isolator Part No 0-605-55 about £10 it fits on the negative battery terminal, very easy to fit takes about 10min.



Thanks Geoff.


I'm a bit confused though (it happens very easily!).....


I thought you were always supposed to fit an isolator on the positive side of the circuit....in my case I'm thinking of fitting it to the two red wires that come from the positive leisure battery terminal, fitted on the fascia of the battery box cupboard about 12" of cable away from that terminal.

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For islolating a system where there are a bank of batteries then it is normal to put a master switch on the pos side this was normal practice in boats where there was a bank of batteries, but where there is only one battery you can either as you say put an externaly mounted isolater on your battery compartment, but it is easier and a lot cheaper to put one on the battery. I have discussed this with my auto electrical centre who also do a lot of marine work, I dealt with them for many years before retiring, they always recommend that it is put on the neg terminal, thereis no wiring to undertake the switch clamps onto the battery terminal and the clamp with the neg lead clamps to the switch there is a plastic knob on the top of it that that you loosen off to isolate the battery. I fitted one to my leasure battery so that could isolate if quickly if there was a problem. What you propose to do is Ok, If you go to your local Marine chandlers you should be able to pick one up from them locally.

hope this helps

Regards geoff

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Many thanks guys for your help and advice.


I've managed to get one of those remote isolator switches with the big red removeable key this lunchtime from a local motor factors (for the princely sum of €6.94). :-D


I'll fit it later this afternoon......after a little spot of al fresco lunch and sunbathing on our sun terrace here.

It's a hard life.......... :D

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