[rescue] NiMH Batteries, test outside computer?

[John Ruschmeyer]

> From: vraptor at employees.org
> To: Rescue Mailing list <rescue at sunhelp.org>
> Subject: [rescue] NiMH Batteries, test outside computer?
> 
> Can anyone offer any pointers for testing batteries
> outside of the computer that uses them?
> 
> I have several NiMH batteries for these Duos that I am
> working on.  The Duos will not boot if they perceive the
> installed battery as "bad".  I am going to try the trick
> of resetting the power manager on the Duos to see if that
> helps them recognize the batteries.

Are these Type 3 batteries by any chance?

Duo Type 3 batteries have an interesting "failure" mode in that the
voltage gets so low that the Duo can not run or boot with one installed.
Putting them into an exteral Apple charger will cause them to try and
charge for a while, but ultimately get the red LED signifying a bad
battery.

The good news is that often such a Type 3 battery is not bad and can
recover to all/part of full capacity. In my case, I've had very good
luck running them through an old Lind SuperCharger II. In the SC2, the
battery usually trickle charges for a while, then drops into regular
charging once a sufficient delta V is detected, until a full charge is
detected. That, and a couple of reconditioning passes brings most of
them nicely back into shape.

(My own experience is with 10- 4 ultimately returned to most of full
capacity, 4 to a diminished but still usable capacity, and 2 refused to
ever take a charge again (though could now reside in a Duo harmlessly).)

Alternately, there is the trick of passing a high current through the
battery for a short duration in order to jumpstart it. I've heard of it
working, but am concerned about possible trauma to battery or operator.

FYI, contact me off list. If we're talking about a relatively small
number of batteries, I'd be willing to put them through my SC2, in
return for postage and some kind of token to make it worth my while.

<<<john>>>