[Top] [All Lists]

Re: Lithium ion batteries (was Portadisc)

Subject: Re: Lithium ion batteries (was Portadisc)
From: Walter Knapp <>
Date: Sat, 06 Sep 2003 02:19:47 -0400
Marty Michener wrote:

> Once again, I have underestimated you.  I should never have guessed in
> advance that you didn't know.  I now begin to understand the dilemma.  Bu=
> Sony seems to have solved it 10 years ago with all their cam-corders.
> What about temperature of the battery inside its case, don't tell me that=

> fussy voltage rating has no nasty temperature coefficient!!??  If the
> charger is in one case and the battery in another - - - how could the
> battery temperature ever be figured into that 1% from inside the
> charger?  Maybe that is one reason all the Li ion batteries have so many=

> connections . . ?
> And BTW ALL those connections had better be good ones. At one amp charge=

> rate obviously all it takes to get 100 mv is 0.1 ohm somewhere TOTAL
> between the cell internals and the charger internals - easy to achieve
> initially, but after several years of sloppy field use??  I think I'll go=

> scrub clean all my LI ion battery connections and chargers . . .

Note that all this precision is necessary if you want two things
combined, fast and full charge. If you are not quite so picky it would
be a little easier.

Some Li ion batteries have a lot of the control circuit onboard. Apple
does it that way.

Some others, like the Sony MZ-R30 batteries were a fairly slow charge.

Yes, temperature is in the equation.

I looked into it all when I first ran into Li ion batteries and asked
pretty much the question you asked. I've forgotten a lot of what I got
on the chemistry that caused the problems. I'd have to go look that up.
It was at least 7 years ago.

Note the two part nature of the charging. The 100 mv problem is in the
voltage control part, after you are done with the high charging rate.
The voltage part charges at a much lower rate. Still it's always a bit
surprising that Li ion batteries and chargers are pretty darned reliable.



Your use of Yahoo! Groups is subject to

<Prev in Thread] Current Thread [Next in Thread>

The University of NSW School of Computer and Engineering takes no responsibility for the contents of this archive. It is purely a compilation of material sent by many people to the naturerecordists mailing list. It has not been checked for accuracy nor its content verified in any way. If you wish to get material removed from the archive or have other queries about the archive e-mail Andrew Taylor at this address: andrewt@cse.unsw.EDU.AU