[VAC] Re: Why Car & Trailer Battery to Univolt?

["Weimers" <mweimer@xxxxxxxx>]

My system does double duty. First it isolates the trailer from the starter
battery., and second, it isolates the starter battery from stupid drivers
who leave their lights on by accident!  So, when I've stupidly left my glove
box door open for a week, or left the lights on over night, I can still
start the car. If the accessory battery is dead, however, there is no power
to run the solenoid to kick over the starter motor. In order to start the
car, I made a jumper wire I can connect to the two battery terminals on the
diode. That way the ignition switch and the relay gets power. I've used this
system for years.

I could do it the way you propose, but then I'd have to trust myself NOT to
leave my lights on ....(a foolish move at best!)


> Also since the wire to the trailer is not capable of handling starting
> the diode isolator keeps the trailer battery from trying to charge the
> starting battery while cranking.
>

Now THERE is a factor I didn't consider!  A 30 amp circuit breaker should
take care of that problem, I should think.

>If
> it needs all that cranking power, I'd be sure the starter circuit cables
> were enlarged a size or two (maybe to 1 or 2 gauge if not 0 gauge) and
> the starter brushes, commutator and bearings were not worn out and I'd
> just hook the two tow car batteries in parallel (as in a diesel).

No, I guess it really doesn't need all that cranking power. I guess you'd
call it "over kill" .

I think you are right about my shunt ammeter. I probably fried it after the
diode was put in. I have a voltmeter in there now to monitor my charging
system.

Thanks for your input.  It sure is great to have this list ...now I don't
have to brain storm alone!

MARC WEIMER
Punxsutawney, PA  -  Home of the Groundhog
#15767
1963 Globe Trotter
1971 Globe Trotter
http://users.penn.com/~mweimer