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.

Amps ...

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

"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