battery drain

[Guest]

Are laptop batteries(or any battery) supposed to drain when they aren't used? I know some laptops will drain the battery even when they are off, do most laptops do this or is it a sign of a particularly crappy laptop.

also, don't batteries lose their charge when they aren't used at all? like if i charged up my laptop battery and then took it out of the laptop and left it on the table, it would lose it's charge in a week or so, right? same with disposable batteries, if you don't use them soon enough they just lose their charge in a year or so, right? correct me if i'm wrong, but can i remember trying to use a 5-year old unopened pack of disposable batteries once and they were all dead.

 

[frozenlead]

All batteries lose energy over time - basic law of chemistry there; electrons like to be in a stable state. Lithium Ion batteries (like those in laptops) show better shelf life with a charge, but they, too, will drain over time. I've known my extra laptop battery to hold a full charge for a week (never tested it past that). Ni-MH batteries lose their charge faster when on the shelf or in the drawer. Ni-Cads even faster. Chemical cells like disposable batteries, though, have much longer shelf lives then all three; the disadvantage, though, obviously being they can only be used once.

But, I would expect a particularly low quality notebook's battery shelf life to be (keyword) somewhat lower - but really...how long do you leave your laptop away from a plug? I suppose it applies if you have an extra battery, but out of all the people I know with laptops, I'm the only one who actually has one.

 

[Guest]

the reason i asked is because i've been thinking about buying an eee pc, but i heard about the battery drain issue that they have and it got me thinking about how much of the drain was actually caused by the laptop itself.

 

[kgrach]

Nicads and NiMh self discharge 10% per week.
Lipo's self discharge about 5% every Six month's.
The main disadvantage of Lithium chemistries is the three year limit.
The life of lithium batteries start ticking the instant they are made.
Example Sony protection circuitry turns off their batteries on the day of their third birthday.


Kgrach