Unused Li-ion battery pack
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From: N_Cook on 1 Oct 2009 09:29 How to store to retain it for possible future use? deliberately discharged and then unattended outside of pc charged up in pc and then unattended outside of pc charged via otherwise unused pc once a month? 6 monthly ? yearly ? and then removed from pc stored in a fridge? or just a cool dry place or a warm place
From: Geoffrey S. Mendelson on 1 Oct 2009 09:54 N_Cook wrote: > How to store to retain it for possible future use? > > deliberately discharged and then unattended outside of pc Will destroy it. > charged up in pc and then unattended outside of pc Yes. If you have an antistatic bag and a moisture abosrber, put them in it and seal it. Keep cool, but do not freeze (as the UNIX fortune program used to say). In case any one wonders, the cells themselves are not affected by static, but the electronics inside the battery pack are. If you are the cautious type, place the anti static bag inside a sealed zip lock bag. If the cells leak, the electrolyte is extremely corrosive. I have no proof, just a feeling, but I would not place them in bag and seal it using a vacuum food sealing system. The cells are designed to not leak at seal level air pressure, not a vacuum. Geoff. -- Geoffrey S. Mendelson, Jerusalem, Israel gsm(a)mendelson.com N3OWJ/4X1GM
From: William Sommerwerck on 1 Oct 2009 10:12 Anti-static bags are conductive. Not like metal, but they conduct. Make sure the battery's contacts are covered.
From: Jeff Liebermann on 1 Oct 2009 12:34 On Thu, 1 Oct 2009 14:29:37 +0100, "N_Cook" <diverse(a)tcp.co.uk> wrote: >How to store to retain it for possible future use? <http://en.wikipedia.org/wiki/Lithium-ion_battery#Shelf_life> Store at about 50% charge in the coldest place you can find. Warm to room temperatures before using. "At a 100% charge level, a typical Li-ion laptop battery that is full most of the time at 25 �C or 77 �F will irreversibly lose approximately 20% capacity per year...." >deliberately discharged and then unattended outside of pc That will blow up the battery. >charged up in pc and then unattended outside of pc Full charge will eventually self-deteriorate the battery. >charged via otherwise unused pc once a month? 6 monthly ? yearly ? and then >removed from pc Nope. Lifetime is measured in charge cycles. That would just decriment the number of charge cycles available. >stored in a fridge? or just a cool dry place or a warm place Cool. Cold is better, but don't freeze. Optionally store in sealed plastic bag to prevent condensation when removed from fridge. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
From: who where on 1 Oct 2009 21:15
On Thu, 01 Oct 2009 09:34:43 -0700, Jeff Liebermann <jeffl(a)cruzio.com> wrote: >On Thu, 1 Oct 2009 14:29:37 +0100, "N_Cook" <diverse(a)tcp.co.uk> wrote: > >>How to store to retain it for possible future use? > ><http://en.wikipedia.org/wiki/Lithium-ion_battery#Shelf_life> >Store at about 50% charge in the coldest place you can find. Warm to >room temperatures before using. > >"At a 100% charge level, a typical Li-ion laptop battery that is full >most of the time at 25 �C or 77 �F will irreversibly lose >approximately 20% capacity per year...." that's seriously dated and extremely inaccurate. It doesn't explain the packs that are ten years older (or more) and still can demonstrate 2/3rds of original capacity. Unfortunately some of these references seem to never track reality. >>deliberately discharged and then unattended outside of pc > >That will blow up the battery. That's also an extreme view, assuming discharge to the "normal" end-point and *not* to zero volts per cell (which is geberally precluded by the pack protection module anyway). Have you ever witnessed that occur? The normal decomposition of cells allowed to deteriorate from EOD is non-spectacular, just a quiet process without the leakage that say an alkaline primary would exhibit. >>charged up in pc and then unattended outside of pc > >Full charge will eventually self-deteriorate the battery. The things that determine the rate of loss_of_usable_capacity are temperature and state-of-charge. Also simple choices (not generally available to the user of consumer appliances) play a big part in cycle life. Lowering the end-of-charge voltage from 4.20 to 4.10 returns a trebling of cycle life in return for a small reduction in usable capacity. >>charged via otherwise unused pc once a month? 6 monthly ? yearly ? and then >>removed from pc > >Nope. Lifetime is measured in charge cycles. That would just >decriment the number of charge cycles available. It isn't that simple. >>stored in a fridge? or just a cool dry place or a warm place > >Cool. Cold is better, but don't freeze. Optionally store in sealed >plastic bag to prevent condensation when removed from fridge. |