On Fri, 29 Apr 2005 02:50:33 GMT, "Bill McKee"
wrote:


"Shortwave Sportfishing" wrote in message
.. .
On Thu, 28 Apr 2005 16:56:12 -0500, Richard J Kinch
wrote:

Tim writes:

Any mismatch is destructive, and eventually, they will mismatch.

I really don't know what you mean by "destructive"

Two equally good batteries should work fine.

No. Currents are at best unstably balanced. Any mismatch (difference)
in the cells (size, manufacturer, model, flooded/sealed/gel/etc, date of
manufacture, age, prior application, usage history) at the start or
developing over time will result in loads between the batteries
themselves, which over time will accelerate the mismatching process.

A shorted cell, not uncommon, will result in enormous currents that can
cause a fire or explosion.

I know it is done, but only as a compromise, and a bad one at that.

I would at least put fusible links in series with each battery before
the parallel connection. That will at least give some protection
against the fire and explosion hazard.

Think of it as yoking a strong horse and a weak horse to a cart side by
side. The strong horse will be spent dragging the weak one. The weak
one will be spent just trying to keep up with the strong. The power to
the cart is a fraction of what the team is exerting.

Whatever.

I guess I better disconnect the 2nd factory battery in my Duramax Diesel
pickumup.

Yes - I must go out and disconnect my diesel batteries in my pickup
truck right now - they might be unstable.

Oh, and my '50 MTA International tractor - can't have that being
unstable. I'll just have to figure out another way to start it -
maybe like pushing it downhill.

Oh, and the storage batteries that buffer the diesel generator for the
house and barn.

I forgot all those diesel electric subs - hell, subs are dangerous
enough, can't have unstable batteries.

They are all unstable, YOU HEAR ME!! UNSTABLE!!!

I also need to get to my professors - if they are still alive - and
tell them that parallel batteries are verboten because the circuit is
unstable.

Here's a quote and a reference:

"Failure mechanisms of deep cycle batteries are described on pages
14-97 thru 14-98 of reference 1. Grid corrosion and plate shedding are
the predominant failures. Neither is a result of parallel
connections."

http://www.amplepower.com/pwrnews/parallel/

Might want to take a look at this one while you are at it.

http://www.batteryuniversity.com/partone-24.htm

I just can't resist - here's one more.

http://www.wagonmaker.com/newbatt.html

And let's not leave a manufacturer out of this:

http://tinyurl.com/acvgb

I have no freakin' idea what this is all about, but it is described as
a Intra/Extra Dimensional Shift - anybody ever watch "Sliders"?

http://nadia.delicata.net/appendixVI.htm

Later,

Tom