Battery cut off switch wiring - the great debate!

Started by moca2cv, November 29, 2021, 16:16

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moca2cv

Hi great and knowledgeable team. I will be relocating the battery to the frunk (it's a track car). I will be splashing out on the Mighty UltraMax NP22-12 (used to good effect on most things I've owned!) but what does the collective wisdom suggest is the best way to wire? In the past, I've just chucked it in the negative, but is there a compelling reason to wire it as per the FIA switch instructions in the positive?

Appreciate your thoughts :) I know a lot of people use the little battery clamp screw disconnect doo dah on the negative, so can't imagine there will be any ill effects, unless its used while the engine is running... I do not intend to use it for anything other than preventing the battery from discharging while sat, but at the same time, for a little extra effort, maybe I should do it as per recommended...

Joesson



@moca2cv
I didn't know the answer to your question so I checked and found this:


Cartek produce two types of Battery Isolator known as GT and XS. Both systems isolate the battery from all electrical circuits in accordance with FIA requirements) by disconnecting the negative terminal of the battery from the chassis/earth. However, the main difference between these two units is the method used to stop the engine.
https://www.merlinmotorsport.co.uk/pages/cartek-isolator-switches-faq-s-291

Iain

Ive done mine on the negative side, had no issues.

Carolyn

Isolating the positive prevents arcing to ground in a rescue (or makes it much less likely), thereby reducing fire hazard.
Perry Byrnes Memorial Award 2016, 2018.  Love this club. 
https://www.mr2roc.org/forum/index.php?topic=63866.0

moca2cv

Thanks all. And thanks Carolyn - that explains why the guidance says to fit it to the positive. Looks like that will be the most sensible thing to do, don't want to be a fire hazard :)

To conclude:

Either is fine, positive is safest. And safety first etc.

Joesson

The isolator switches referred to in the link that I posted are RED! For a reason?



moca2cv

Quote from: Joesson on November 29, 2021, 22:58The isolator switches referred to in the link that I posted are RED! For a reason?


I'm sure, but I'm not fitting one of those :)

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