Re: Diode in NiCd pack - what is it?

From: mike (spamme0_at_netscape.net)
Date: 01/13/05 

Date: Thu, 13 Jan 2005 07:30:57 -0800

DaveC wrote:
> Panasonic 2.4v screwdriver battery pack consists of 2x sub-C cells in series.
> Pack has (+) and (-) terminals, and a 3rd terminal (charge sense?).
>
> This 3rd terminal connects the charge circuit to the pack's (-) terminal
> through 2 diodes and 2 resistors, all in series. The diodes are glass with a
> yellow band. When I hook it up to the charger, the diodes each drop 0.535v.
>
> What are these diodes? Germanium would drop 0.3v or less, and silicon would
> drop more than this 0.5, no?
>
> I want to make more battery packs for this screwdriver and need to identify
> these diodes.
>
> Thanks,

This has been another of those amusing threads.
You've gotten a zillion "answers" each of which could be paraphrased,
1)Stick your finger in the air, or your favorite orifice.
2)Make a GROSS, UNSUBSTANTIATED, SPECULATION based on NO, NONE, NOT ANY
information.

I read the thread again. I couldn't even find mention of the polarity
of the diodes in the circuit. Heck, one of us might even have relevant
information if only we knew the Panasonic model number.

You need to take apart the CHARGER and reverse engineer that.
If you published the schematic of the battery and charger, you MIGHT,
maybe, get a useful bit of information buried in the inevitable noise.
Then your problem would be reduced to deciding which of the conflicting
opinions to choose.

IF the charge termination is indeed based on temperature, and IF the
unknown elements are involved in temperature sensing, you need to
GET IT RIGHT. Did I mention IF???

Nah, who am I kidding. I'm certain the diodes are not diodes at all.
They're put there just to add to confusion in internet newsgroups.
Leave them out. Bummer, I think I got something on my finger... ;-)
mike 

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