Re: laptop battery cycling
On 28/05/12 14:01, Doug wrote:
> On 05/27/2012 09:57 PM, Scott Ferguson wrote:
>> On 28/05/12 11:37, Robert Holtzman wrote:
>>> For the record, I'm running a Lenovo T420i with a 6 cell battery.
>>>
>>> In the past I've been told that it's bad practice to run a laptop on
>>> AC with the battery installed because it would cause reduced battery
>>> capacity.
>> Your Li-ion battery will have a longer life if it's stored in a well
>> sealed plastic bag in the 'fridge with a 40% charge than on constant
>> maintenance (trickle) charge plugged into the laptop. Take it out of the
>> 'fridge and fully charge prior to using. Keep it in the 'fridge state
>> when running on mains.
> /snip/
>
> I've often wondered, after reading this advice time and time again:
> how do you determine that the battery has a 40% charge?
>
> --doug
>
>
Depends on the laptop.
With the Thinkpad/Levenos - a battery charge indicator in the BIOS
and/or read the state from tm_smapi (acpi tends to be very inaccurate).
Both methods are only reliable when the battery gauge is "calibrated"
using the BIOS tool (the older the model, the more often that is required).
I usually use kde-power tools set to shutdown at 40% and just leave it
running till then. After shutdown I bag the battery with a little dry
rice and put in the 'fridge (gas tight freezer or oven bags, not
polyethylene). The rice desiccant is to absorb any moisture that
condenses on the cold battery when you remove it from the 'fridge
(LiAlH4 likes water).
NOTE: I've discovered that even if the battery has been in a warehouse
on a shelf unused for 4 years - it has little useful life left. Those
genuine Thinkpad/Levono replacement battery bargains from China on eBay
aren't always bargains. If the laptop is more than 2 years old, buy a
recent repacked or third party battery - not an original.
I could be wrong - in which case I've got some original Toshiba
PA3356U-3BAS and ASUS U5FL721 batteries at postage prices (make great
paperweights and conversation pieces).
Kind regards
--
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