Date: Mon, 29 Jul 2002 22:50:48 -0400
Reply-To: Myron Lind <mdlind@RICA.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Myron Lind <mdlind@RICA.NET>
Subject: Re: Batteries in parallel?
In-Reply-To: <009901c23762$b46d9b80$ca5fd63f@earthlink.net>
All the over the road truck I have seen had 3 or 4 batteries in parallel. As
one several month old battery would fail, only one would be replaced, not
all. Usually they broke due to a plate breaking off and shorting out the one
battery. While trucks do spend a lot of their time running (charging), many
of them sit (i.e. new on the lot for months on end) and there are no
troubles with that.
I also hooked two batteries in parallel on a tired old diesel rabbit to help
it start. It cranked much faster with the two batteries. It was typical use
of a car. One new battery, one 3-4 year old battery. No problems with that
either for the last 4 years of its life.
While there is theoretical merit to each battery draining the other there
seems to be very little automotive data to back this up.
Myron Lind
Harrisonburg VA
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf
Of JM/CO
Sent: Monday, July 29, 2002 8:48 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Batteries in parallel?
It is never a good idea to leave batteries connected in a parallel
arrangement unless the following conditions are met
1) The circuit is in ( or near ) constant use, where frequent charging is
happening.
2) The batteries are connected in parallel temporarily by a switch for
purposes ( let's say ) of starting an engine with partially depleted
batteries, and than, after the engine is started, the switch is restored to
the non - parallel mode. This is a common marine arrangement.
Batteries connected in parallel in other than the above situations will tend
to discharge each other, as the odds of their internal resistances being the
same ( required condition for zero current flow ) are next to impossible.
Chuck
'83 Westy
'84 Jag XJ-6 VDP
-----Original Message-----
From: George Averill <averill@LDL.NET>
To: vanagon@GERRY.VANAGON.COM <vanagon@GERRY.VANAGON.COM>
Date: Sunday, July 28, 2002 4:30 PM
Subject: Batteries in parallel?
Does anyone have any information concerning problems which may result from
connecting two 12 v. batteries in parallel to obtain more current? Seems
like I remember that there are problems to be considered, but can't remember
exactly what the problems were. Maybe some solutions?
George