|
|
|
|
|||||
|
||||||
From: C. Marin Faure (no email)
Date: Tue Dec 02 2003 - 01:17:19 EST
From: "Brent" <>
Subject: TWL: RE: Re: Battery charging question
>>Bob Austin wrote:
>>There has been form of "combiner" around for at least 40 years on
RV's--basically when you turn on the ignition switch, a relay connects the
house and engine start batteries.
>Brent wrote:
>What happens when the "house" battery bank is badly discharged and you try
to start the engine? Does not sound good to me.
I've had a situation where one of the cells in the house 8D battery shorted
or died altogether, and the rest of the battery was drawn down to only a
few volts. I held my breath when I hit the starter button on the first
engine, which on our boat engages a relay that combines both house and
start batteries together, and the first engine turned over and fired as
rapidly as it does when both house and start batteries are up to full
charge. Same with the second engine. I understand the notion of a dead
or weak house battery drawing down the start battery to the point where
there's not enough to turn over an engine, but it doesn't seem to work that
way in practice.
As I said before, I'm pretty ignorant of how electricity works, but if you
have two batteries, one fully charged and the other almost discharged and
you combine them together, do you not have the sum of the power available?
So you'd have the fully charged battery's power plus whatever meager amount
is left in the discharged battery. So it would seem to me that even if
some of the power is "flowing" into the discharged battery, when you
connect them together with the starter combiner relay, you get the benefit
of whatever's in both batteries. I'll be the first to admit the
possibility I've got it wrong, and perhaps it doesn't work this way with a
more sophisticated system. But with a pair of low-tech 8D wetcells and a
starter relay that connects them together when you hit a start switch, this
is the way it seems to work.
_______________
C. Marin Faure
GB36-403 "La Perouse"
Bellingham, WA
_______________________________________________
http://lists.samurai.com/mailman/listinfo/trawler-world-list
To Unsubscribe send email to
Include the word "Unsubscribe" (and nothing else) in the subject or body of the message.
|