Lotus Elan and Lotus Elan Plus 2 Forums

My 68 S3 which is still wired 'positive earth' has a Discarnect battery isolator fitted, it works fine and provides some 'peace of mind' when left against theft & fire.

My question is - 'which side of the battery should device be attached'. At present its on the negative terminal - Is this correct ???

Ideally Paul, you want your cut off device on the earth cable, but I do not think it makes much difference, so long as you can get to it in the event of fire. And as you state, a great theft prevention measure.

On my cars, I have them fitted to the negative cables, which are all earths, being Sprints.

Leslie

THis has been discussed before.

See:
elan-mods-f31/battery-cut-off-switch-t27407.html?hilit=%20isolator

lotus-electrical-f38/battery-cut-off-switches-t31063.html?hilit=%20isolator

Thanks for the replies

The links to the previous threads seemed to have sparked some lively debate (no pun intended) and include some good info. and interesting alternatives to battery isolation.

Short term I will fit the Discarnect device to the positive terminal at the next service.

Thanks Leslie and Bill

Fitting it on the earth side will offer very little theft protection.

AHM wrote:Fitting it on the earth side will offer very little theft protection.

Why would that be?

John

This is an interesting subject in that what seems the most logical and reasonably is, in my 'umble opinion, not necessarily so.

Perceived wisdom is that the "earth" is isolated as that is the one that should, on a battery, be disconnected first. No return path, no circuit, no nasty consequences for slipped spanners.

However is an isolator the same? All the potential electrickery is still being fed to where ever. And, if it is accessible it would be easy to bridge with a jump wire. Perhaps that it what was meant by -

AHM wrote:Fitting it on the earth side will offer very little theft protection.

Would it not be more logical to isolate the "live" so there is no power anywhere? I intend to fit a second secret isolator inside. Up under the dash? Buried in the carpet by the seat? Somewhere that can be easily operated without being obvious.

It makes no difference. A potential thief could connect the negative battery terminal to an earthing point but It`s hardly likely. He could just bypass the isolator whether it`s + or - anyway but, in reality, he`s going to winch it onto a trailer or lorry most probably.
Jim

jimj wrote:It makes no difference. A potential thief could connect the negative battery terminal to an earthing point but It`s hardly likely. He could just bypass the isolator whether it`s + or - anyway but, in reality, he`s going to winch it onto a trailer or lorry most probably.
Jim

that is if he/she knows an isolator is fitted and if he/she has remembered to bring his multi-meter along with his jemmy and swag-bag and enough technique to reason that the earth lead had been disconnected and not put the non starting down to Lotus electrics

John

jimj wrote: in reality, he`s going to winch it onto a trailer or lorry most probably. Jim

This possibility was anticipated by Lotus who added lightness by not providing any sort of towing hook. Astounding foresight. An obvious additional argument against a Spyder chassis perhaps.