Re: parallel packs?

["David Roden" <roden ald net>]

"Max Hall" <maxo iname com> writes:

> should a person put a second pack of batts in
> PARALELL with the first, or should I SEPARATE the circuits to make the
> traction pack drive the tractor, and the second pack just do the thrower?

I would be careful about paralleling poorly matched battery packs.  If 
they were the same age (had the same number of cycles) and were the same 
brand and type, that would probably work OK.

With a mismatch, you can have one pack drained before the other.  Usually 
it will be the weakest cell which goes first.  Normally, when this 
happens, you notice the loss of power and quit working.  However, with 
the other pack still providing power, you wouldn't notice the weakness so 
much, so you could end up reversing that dead cell.  At best this will 
pretty well ruin it; at worst, you could blow it up.

I wonder if you could put a *big* diode in series with each pack before 
paralleling them.  That way both would supply power, but they could not 
charge each other.  I'm not an engineer, so I'd ask someone who knows 
more before trying this.


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