> I don't get this part. The discharged battery is essentially a "load" to
> the charged battery. Whenever I've put a large load on a battery, either
> the wiring was sized to handle the load, or the wire gets super hot and
> melts stuff. I don't think there will be enough resistance in
> the wire to limit the current.
Well, for sake of argument, let's say the trailer battery has been run down
to 9 volts, which is a pretty deep discharge (not good for the battery), and
the truck battery is at 12.6. 25 feet of 14 AWG is .075 ohms, so 3.6 volts
will drive 48 amps through it (until the voltage on the trailer battery
comes up, which will happen within seconds). That's a dissipation of about
7 watts/foot, which shouldn't be a problem for that short period of time,
especially for a wire run in the open (although of course it wouldn't meet
NEC standards).
All I can say for sure is that we used to do it at the end of every camping
trip, and never had a problem.
Randall
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