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Discussion Starter #1
I would like to install a disconnect switch for safety on the track and convenience during maintenance.

In searching for switches, I have found two types; switches for cars with alternators and switches for cars without alternators.

With Eliges, are there any harmful consequences to a system like this:

Alternator---battery---switch---starter & rest of the vehicle electrical system
Everything but the switch would have its own ground.

I am proposing this system because it seems to be the most simple. Am I missing some untoward effect of simply opening the circuit at that point?

Thanks,
 

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Haven't heard of this myself. Maybe I'm missing something but I would just install a beefy switch (http://www.reallylightstuff.com/electrical/cutoff-switch-kit/) between the battery post and the rest of the electrical. The only thing storing energy is the battery (and maybe ecu, but it won't discharge to the rest of the car)
 

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Discussion Starter #3
The alternator needs to be switched off also to stop spark and fuel pump if the engine is running.
 

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The alternator needs to be switched off also to stop spark and fuel pump if the engine is running.
If you cut the battery out of the system, the car (and by virtue the alternator) will never see any power.

With no spark or fuel, I can tell you the engine won't be running. Are you wanting to turn the car on, then cut power to the alternator and have everything run off the battery? Maybe you should explain a little more what it is you're trying to accomplish...
 

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Discussion Starter #6 (Edited)
A battery disconnect switch does not disconnect the alternator. The alternator can still power the ignition and fuel pumps if the ignition is switched on. The purpose of a master disconnect switch is to provide a single switch to disconnect the battery and alternator. The RLS switch is just a battery disconnect.

I was confused: I was treating my 4 wire alternator as a 1 wire alternator. Different circuit designs apply to each.

It appears that a two pole switch that disconnects the battery and the alternator's field exciter wire is what is needed. This safe guards the alternator if the switch is opened while the engine is running and the ignition is on.

Does this sound correct?

I'm thinking of using one like this:link

Will the field exciter wire be cold with the ignition off and +13v with the ignition on? Will the other wires in the alternator harness behave differently? I can't tell from looking at it which small wire in the alternator harness is the field exciter wire.
 

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This is what I run,

Battery Isolator



and yes you are right, in that you have to isolate the alternator as well as the battery. You can actually isolate the excite wire or the charge wire to the battery.
 

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ah i understand now... for some reason it didnt come across to me in your first postings. Doesn't look like there is a ton of info out there... maybe check scca or lemons rules? they might be able to provide some guidance on safe setup? Other ideas would be to contact one of the sponsors that run race cars, they might be able to help too.
 

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Discussion Starter #10
I ended up using this: Longacre. Works perfectly. Very stout construction.
 
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