"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.

Later,

Tom

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

Bill McKee writes:

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

What you have is a compromised, but not uncommon, design. The biggest
batteries commonly sold aren't big enough for starting diesels. It would
be better if they put two 6V of the same size in series, or used a 24V
starter from two 12V in series, but it's cheapest to do it like you have.

"Richard J Kinch" wrote in message
.. .
Bill McKee writes:

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

What you have is a compromised, but not uncommon, design. The biggest
batteries commonly sold aren't big enough for starting diesels. It would
be better if they put two 6V of the same size in series, or used a 24V
starter from two 12V in series, but it's cheapest to do it like you have.

woooooooooosh

Bill McKee writes:

woooooooooosh

"Richard J Kinch" wrote in message
.. .
Bill McKee writes:

woooooooooosh

"Richard J Kinch" wrote in message
.. .
Bill McKee writes:

woooooooooosh

"Richard J Kinch" wrote in message
.. .
Bill McKee writes:

woooooooooosh



And a few more

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

Perhaps I wasn't clear. Paralleling lead-acid batteries is done, but
its not a good idea. If series is possible then use series. I believe
your reports of using them all over diesels where there is no other
option that cheap, but that doesn't mean it is a good idea for a little
trolling motor.

Shortwave Sportfishing writes:

"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."

A thoroughly shallow analysis, followed by ignorant opinions like: "a
cell rarely, if ever, shorts with a low resistance". All from somebody
trying to sell you something.

I suppose if you have never seen a car battery explode, you might not
believe the warnings, or at least you might not treat them with respect.
I know I didn't, until it happened. I still jump car batteries when the
need arises, but believe me, I do it with care and wearing protective
gear.

I'm not gonna get in a citation war. Look at lead-acid battery mfr
sites and you'll find they typically caution against paralleling if they
address the issue at all.

This religious advocacy of a poor practice reminds me of people who
advocate using suicide cords for portable generators. Yes, they work,
yes its done (and I have done it myself), but it isn't a good idea, and
it risks some serious problems.

On Sat, 30 Apr 2005 00:33:26 -0500, Richard J Kinch
wrote:

~` snippage ~~

I'm not gonna get in a citation war. Look at lead-acid battery mfr
sites and you'll find they typically caution against paralleling if they
address the issue at all.

Look, your position is ridiculous and silly.

Just admit it and move on.

Later,

Tom