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View Full Version : Care and Feeding of the Lithium-Ion



mystro544
04-07-2006, 12:38 PM
I'll soon be switching to a camera with Lithium Ion 3.7v and needed specs
on maintaining them...naturally Usenet had the battery thread,a repost with credits below:

*****
From: Paul Cordes - view profile
Date: Thurs, Mar 13 2003 6:28 pm
Email: "Paul Cordes" <late*ma...@usa.net>
Groups: rec.photo.digital


You get slightly different opinions from different LiIon manufactureres, but
the common thread is that they should not be stored fully charged.
Partially discharged is OK, probably anything less than half charged.
Storage seems to mean for a matter of months, but nobody really defines
this.

A completely discharged battery can be damaged by the normal charge current.
I don't understand the electrochemistry of this, but all of the sources seem
to agree on it. The remedy, if this happens, is to charge it with a very
small current (C/50 or less) until it reaches a level where it can be safely
chrged with normal current. 6-8 hours should do it nicely. In reaqlity
this should never happen if you recharge it (and then partially dischrge it)
every few months. Most batteries these days contain a smart chip which
contains a charge meter, overcharge sensing, and shutdown to protect against over-discharge. If it gets too low, the chip will usually allow a trickle
charge until the voltage is high enough to be safe. I'm confused by the
statement "The battery may not be able to be recharged if completely
exhausted" as it would seem to mean that the chip cuts off all charge after
that and doesn't allow the trickle charge.

If the battery has more than 2 contacts, it's safe to assume it has a chip.
For more (and maybe better) information, try this question on the newsgroup
sci.chem.electrochem.battery



> Also, each battery says 3.7v on it - yet the camera's power jack says "DC
4.7v".

The battery is nominally 3.7 v through most of its useful charge depletion.
The charge circuitry in the camera requires 4.7v (or so) to provide the
proper regulated charge voltage/current to the battery.