Ok,  That is good info.  Thank you.  If I were to get 5 years of a laptop 
battery used under normal conditions, I'd be very happy.

------------------------

Keith Smith

--- On Sun, 7/22/12, Joseph Sinclair <plug-discuss...@stcaz.net> wrote:

From: Joseph Sinclair <plug-discuss...@stcaz.net>
Subject: Re: Laptop Battery Life
To: "Main PLUG discussion list" <plug-discuss@lists.plug.phoenix.az.us>
Date: Sunday, July 22, 2012, 11:30 AM

Current Li-Ion chemistry is much improved from a few years ago, and 
self-discharge rates are a lot lower (hence the amount of charge left after 6 
months).

It's fine to keep the battery in a drawer (cool/dry, of course) and charge 
every 6 months.  They will probably last longer, but perhaps not for the reason 
you would expect.
You also have to accept that you loose the advantage of the built-in UPS-like 
behavior of a laptop with a battery, but if you have an external UPS, you may 
be OK with that.

For storage you actually want to partially discharge the battery (to 80%) 
before putting it away; Li-Ion has self-damaging chemistry at both 100% and 0% 
(whiskering and swell-cavitation), so you want to discharge to 80% before 
storing it, then charge back to 80% before it drops below 30% (typically 6-9 
months, check it monthly to be on the safe side).

Recent systems won't "cook" a battery, the charge circuits automatically avoid 
overcharge, but any (commonly available) Li-Ion kept at 100% charge for too 
long will develop internal shorts due to the whiskering effect of high charge 
separation combined with corrosive internal chemistry.  Whiskering does take a 
rather long time, however, typically 3-5 years for good quality batteries.


On 07/22/2012 09:12 AM, keith smith wrote:
> 
> Sometime ago we discussed laptop battery life.� I asked the question about 
> leaving the battery out and if that would extend the life of the battery.� 
> I'm not sure that option was explored.
> 
> Last December I took the battery out of my two lap tops.� I use both daily 
> for about 15 or 16 continuous hours.
> 
> I have been thinking the batteries might be fully drained by now.� Much to my 
> surprise the newer laptop's battery was at 81% and the older laptop's battery 
> was at 58%.
> 
> Both are taking a charge.� After they are fully charged I will put them back 
> in my desk drawer and charge them again in 3 to 6 months.
> 
> I've have had poor performance from laptop batteries and did not want to 
> "cook" these.� It will be interesting to see if this extends the life of the 
> battery.
> 
> Any thoughts?
> 
> ------------------------
> 
> Keith Smith
> 
> 
> 
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