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post #6 of (permalink) Old 08-25-2014, 05:41 PM Thread Starter
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Join Date: May 2008
Location: Grand Rapids, MI
Posts: 606
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.


06' Fed Elise

My frame, rear subframe, steering rack, A-arms, front crash structure, suspension uprights, and fuel tank are stock.

Last edited by jasondew; 08-25-2014 at 06:08 PM.
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