DANMAS@aol.com wrote:
>
> As for the use of parallel batteries in trucks, are you sure they don't use
> some type of isolation scheme, such as the use of rectifiers, to prevent
> this? I would be interested in learning more about this.
I have this fiberglass, shiny hulled, money magnet in the driveway (it
spends almost _all_ of it's life there) and it is running two batteries.
One to get the motor pointed to the dock in the middle of the night and
the other for everything else.
There is, of course, a battery isolator that prevents one battery from
'seeing' the other battery and there is a switch to select whatever
battery you want for starting. I'm assuming the isolator is just a
couple of really big diodes as the alternator can't 'see' either battery
if hooked up ahead of the isolator and this plays hell on an alternator.
What I did is just have the alternator output hooked to the switch for
the batteries. Thus it always 'sees' whatever battery is the main
battery and the isolator then splits whatever charge current is
generated between both batteries. This has worked well for five years.
Both batteries are still healthy and, when spooking fish in the middle
of the night with lots of lights and Willie Nelson, the boat always
fired up in the end.
Now I don't know what you need all that juice in an LBC for. It ain't
like your trying to fire up a high-compression small-bock V8 or nothing.
But it you did have a need for two 12-volts in an LBC, then the hot set
up from the Marine world is a 'two wire' alternator. This is a Delco
style 'one wire' alternator except two charging circuits are used
specifically for two batterys. This elimnates the need for the isolator.
And it wouldn't be too hard to cobble up a couple of old Ford starter
solenoids to give the starter a double dose of cranking power.
Howsumever, I was under the opinion that two heavy duty 6 volt batteris
could, in fact, out-amp two 12 volts in parrallel. Less cells should
leave room for more plates. But that may be 'old' wisdom and they just
don't make healty six volt batteries anymore. And another thing, I
thought big disels use 24 volt systems anyway.
I'm done now,
Bob Allen, '69CGT, '75TR6, derelict '61Elva yard car
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