On Sun, 8 Feb 2004, M.Hockings wrote:
I think that most modern laptop batteries are "smart", that is they have a chip that tries to keep track of the battery's available power. If you don't completely discharge the things once in a while they kinda forget about the rest of the battery. Going from memory I think the way to recover some of the lost capacity is as follows. Power off the machine, then power it back on to the power on password or hold it in the bios setup or whatever until the battery completely dies. Then plug it in and let it completely charge. That should help calibrate the chip. I seem to recall reading in the specs for one laptop about how long the battery would last when new and how long when 1 year old. It was diminished by a significant amount.
Mike
Joel Jaeggli wrote:
Batteries wear out. discharging lithium-ion or polymer batteries to the end of their usable charge is a good way to damage them faster...
to quote some motorola engineers:
The relationship between DOD (depth of discharge) and cycle life is logarithmic. In other words, the number of cycles yielded by a battery goes up exponentially the lower the DOD. Research studies have shown that the typical cellular phone user depletes their battery about 25 to 30 percent before recharging. Testing has shown that at this low level of DOD a lithium-ion battery can expect between 5 and 6 times the cycle numbers of a battery discharged to the one hundred percent DOD level continuously.
http://www.motorola.com/ies/ESG/testlab/article1.htm
I did not say to do it continuously, just as a way to reset the battery chip.
I believe that the recommendation with IBM Thinkpads is to do it monthly though I can't find the doc right at the moment.
Mike
