Battery Cut Off

[dzorde]

I had the same problem.  You can actually buy battery cut off switches that
has the provision for cutting the alternator feed to the battery as well.  I
guess it has a seperate small switch inside for this.  The other solution is
to make sure that all power for any electricals is taken from the
non-battery side of your switch, and feed your alternator charge lead
directly to the battery.  That way when you kill the switch, all power is
cut, and even if the alternator is still charging the battery it will be
isolated from the car electronics.

Dan     dzorde at geocities.com
>
>OK a slightly unrelated one for you guys and girls
>
>under our country's racing authority the battery isolation switch has to
>also shut the engine off. Currently most alternators go low on the load
>side and produce balisitic voltage in the abscence of the battery
>risking computers etc, and the car chugs on quite happily.
>The trick is to insert a relay in the field actuator of the alternator
>wiring(my alternator is external regulated) and then find a source that
>is high when the engine is running and the batt switch is closed but
>goes low when the batt switch is open. Problem at the moment is that
>there is enough back emf in the system that the source from the output
>side of the batt switch never goes low enough. i experimented with a
>diode but logic should have told me not to bother. in one way when the
>switch is closed and engine running the diode will let current through
>to the relay switch, but of course it will also do this when ths switch
>is open, the other way round its blocks the current all the time so the
>alternator never charges. Any suggestions
>
>Anyone....Anyone.... Beuller??
>
>regards
> 
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