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Re: [Phys-l] lithium batteries



The new Lithium Polymer batteries (LiPo) also have many of the
characteristics mentioned by various posters. I use them extensively on
radio controlled gliders - they definitely do not charge as well
outdoors in the cold. The package labels emphasize long term storage at
half charge. They also recommend charging the batteries in a fireproof
box as they tend to catch fire and sometimes explode.

Bob at PC

-----Original Message-----
From: phys-l-bounces@carnot.physics.buffalo.edu [mailto:phys-l-
bounces@carnot.physics.buffalo.edu] On Behalf Of John SOHL
Sent: Wednesday, January 09, 2008 12:35 PM
To: phys-l@carnot.physics.buffalo.edu
Subject: Re: [Phys-l] lithium batteries

I've been doing a lot of research on batteries and battery charging
for a
camping tent light product that I've developed called the "firefly"
(patent pending). Charging and discharging batteries is a remarkably
complex process. All chemistry is temperature dependent and battery
behavior involves a lot of chemistry and physics. Here is an inside
tip.
If you charge your Li ion batteries in the garage or other cold (or
particularly hot) environment, you might want to change that. Unless
you
know for a fact that your charger was designed for charging cold
batteries, you should charge your batteries at room temperature. (An
option that I don't have with a camping product. Thus, I've had to
build
in ambient thermal sensors and battery thermal sensors as part of my
charging circuits.)

One of the best web sites that I've found with general information at
a
level that is a fast and easy read is the Battery University. The page
of
interest for the discussion on battery storage and lifetime is:
http://batteryuniversity.com/parttwo-34.htm

Note, battery composition is not a fixed thing. Different
manufacturers
use different balances and elements from each other. Thus, it might
well
be true that a particular battery is best stored dead, but everything
I've
been reading says you should store your Li ion batteries somewhere
between
40% and 100% charged depending on how often you use the battery.

John

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
John E. Sohl, Ph.D.
Professor of Physics
Weber State University
2508 University Circle
Ogden, UT 84408-2508

voice: (801) 626-7907, fax: (801) 626-7445
e-mail: jsohl@weber.edu
web: http://physics.weber.edu/sohl/

Jeff Radtke <jr@cloudchambers.com> 1/8/2008 8:55 PM >>>
According to these people, lithium-ion batteries are best stored at
40% charge:
http://www.batteryuniversity.com/partone-19.htm

The newer A123 lithium nanophosphate batteries are best stored at
higher levels of charge, about 95%.
http://www.rcuniverse.com/forum/m_5048617/tm.htm

The A123 cells are fantastic: best cycle life with highest discharge
and charge currents. I built a cyclemotor that uses them:
http://www.neodymics.com/drivetrain.htm

--
Jeff Radtke
jr@cloudchambers.com
www.cloudchambers.com

Who stores all of his alkaline and zinc/carbon batteries on the fridge
shelf, where they last at least twice as long. See Fig 14.2.E in
Horowitz and Hill's "The Art of Electronics."


Quoting Bernard Cleyet <bernardcleyet@razzolink.com>:

New to me. I'll query the PHYS-L crew

T.K.Wang & Mary Brooks wrote:

According to the Canon instruction book, a lithium battery wears
itself out by being charged. they recommend DISCHARGING a battery
and
then storing it (when for a long time) and charging it the day of
use.
Just the opposite of Nicads.
T.K.


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_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l