The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
Subject: Re: Reducing contact resistance for low volt use?
Date: Wed, 11 Dec 2002 14:39:45 -0800
X-Mailer: Mozilla 4.78 [en] (Win98; U)
References: <email@example.com> <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <email@example.com>
Here's some data
I took number 6 solid copper wire and rounded the
slightly. Mashed a pair of them onto the negative
end of a D-Cell
NiCd. Shined up the end of the cell with a
pencil. I pushed hard. My springs run out of gas
at about 10
pounds, so total pressure was probably 20-30
Lowest resistance I could get was 0.8milliohms.
That's 0.4 milliohms/contact point. That doesn't
include any of the
wire or connection clamps. Multiple contacts
with independent springs should reduce the
Here's a picture of the jig.
With such low voltage margin for the load, you
to resort to using a hall-effect current probe in
feedback to set the current for a passive
load...well not passive,
just not using a KW of power to create the load.
More volts would help. Can you discharge two or
more at once, but
just measure across one cell? That would make the
load design a
What characteristic of the cell are you using to
determine it's health?
Could you use a pulse measurement? That would
help the heat problem
Might be interesting to put a cell on a curve
tracer and see if you can
John Muchow wrote:
> >>>Looking at a RatShack c-cell, it has a big shiny top contact that's
> >>>most of the overall diameter across (and has the small, regular
> >>>contact bump in the middle.) It should be easy to hit this with 50 or
> >>>so pogos on each end, plus one extra for a Kelvin contact.
> Hmm...I could solder them all to a hunk of copper or silver (stepped
> so the outer Pogos can reach the battery terminal) and then solder (or
> bolt/solder the connector) the 4AWG wire to the same piece to connect
> to the discharger.
> I wonder if that would be better than just having a stepped copper or
> silver plate contact that would press directly against the battery. I
> guess a lot depends on shape of each cell...gotta check that.
> John Muchow
Bunch of stuff For Sale and Wanted at the link
Tek 2465, TFT projector, ham radio, 30pS pulser
Tektronix Concept Books...
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup