Makes me kinda glad for my little honda generator. Been there where the
wind died and drifting for shoals...batteries were too dead to start the
diesel. Went to start the Honda...found the end of my shorepower cable
(connecting the honda to the boat ) came off..here I am rewiring is before I
can charge the battery, before I can start the engine. Fun.

Glenn.
s/v Seawing
www.seawing.net


"Larry" wrote in message
...
Dave wrote in
:

OK, so I've been using the house battery and run it down pretty low. I
now want to start the engine and charge both batteries. Is your
suggestion the I start the engine on the starting battery, run it a
bit, shut it down, switch to both batteries and the complete the
charging?



Naw....Put 'er in BOTH, crank the engine, and run it. Sure there's going
to be current from the starting battery to the dead house batteries for a
few seconds until you hit the starter and draw everyone's voltage down
below 11, but it'll make no difference, whatsoever. As soon as the
engine cranks, the alternator's load will be very heavy on the house
batteries for a few minutes hauling them up to 12V when the voltage
starts causing charging current, instead of the discharging current
that's been going on since you threw the switch to BOTH, but that won't
hurt it any more than cranking a dead car with another car and a pair of
jumper cables...same circuit.

I always get a kick out of watching people in a panic quickly
disconnecting the jumper cables the instant the dead car starts as if
something is going to explode! How silly. Let the alternator of the
cranking car help give a boost charge current to the dead battery before
disconnecting it. If one alternator has a higher voltage limit, it won't
matter as long as there's a dead battery in parallel...loading the hell
out of both of them.

I think a lot of these tales about blown alternators, parallel batteries,
etc., goes way back into the generator days with the vibrating mechanical
voltage regulators rapidly pulsing the generator fields on and off. The
old generators didn't like it when the battery circuit opened as the
voltage regulators weren't made to just shut down, entirely, and the
generators, themselves, would run away from their own stored magnetism,
overvoltaging the hell out of everything! The solid state regulator
simply shuts down the field current, all the way to zero if necessary.
It's not rocket science, nor some Wicca curse.