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cut-off switch vs alternator

Subject: cut-off switch vs alternator
From: Randall <randallyoung@earthlink.net>
Date: Mon, 03 Apr 2000 17:20:15 -0700
Cc: triumphs@autox.team.net
References: <009601bf9d8d$e52c52a0$3d64a8c0@ptegler500.gouldfo.com> <00ea01bf9d9f$2d70eec0$086eaccf@vafred> <3.0.6.32.20000403200404.03429b20@pop.nefcom.net>
Don :

The issue is that disconnecting the load (battery) from a running
alternator may fry both the alternator and you (it can generate lethal
voltages).  

The more sophisticated switches deal with the issue by having a separate
terminal for the alternator, which is shorted to ground through a
resistor before being disconnected from the battery, so the alternator
never sees "no load".

As a side issue, even with a generator, the simple (one circuit)
disconnect switches do not guarantee that the engine will stop when the
switch is opened.  Even at idle, the generator/alternator will
frequently produce enough power to continue to run the ignition.

Randall

Don Marshall wrote:
> 
> I missed the first part of this thread, so if this has already been
> covered, please excuse me.   As one who is "electrically challenged" but
> curious, would you please explain the alternator issue and how the more
> sophisticated switches handle it?
> 
> Thanks...
> Don Marshall

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