Re: Sealing NiMH Battery Pack?

If you have a large number of cells in series, and allow the pack to
discharge completely. One or more of the cells will reverse charge, and
release hydrogen. I once saw a device using 18 NiMH cells in serial mounted
in a steel tube with a cork in both ends. The tube was opend for charging,
and the device was turned on and cealed.
It was then submerged until the battery was compleatly drained and then
some, after recovery one of the end corks removed it self with conciderabel
force ( and a loud bang).
So make sure you can release any overpresure inside the enclosure, and make
sure you don't cover the safty valve on the cells with resin or glue etcetra
( belive me i seen "profersonals" do it).

Steinar

<[EMAIL PROTECTED]> skrev i melding
news:[EMAIL PROTECTED]
> Robert <[EMAIL PROTECTED]> wrote:
> > Hello,
> > Can I permanently seal (make waterproof) a pack of NiMH batteries. The
> > reason I am thinking I can't is because of off gassing of the cells.
> > Should I be concerned about this or not. If it is a concern does anyone
> > have any ideas about making a pack waterproof?
> > Thanks.
>
> This should only be a problem when charging.   The only time you will have
that
> problem while submerged is if you wire the batteries in parallel and
> one goes bad, causing the other to try to charge it.
>
> Princetontech fixes the problem by including a small capule of some
> hydrogen absorbing chemical (a platinum catalyst)  in their multiple
> cell flashlights.
>
> Interestingly, these don't build up enough presure to blow out the case,
but
> do explode in when a spark is created by attempting to remove the battery
or
> turning the light on/off.
>
>
> See
:http://www.candlepowerforums.com/ubbthreads/showthreaded.php?Cat=&Board=UBB
1&Number=318168&page=&view=&sb=5&o=&vc=1 for an interesting discussion.
>
> Daniel