[EMAIL PROTECTED] on 05/02/2000 12:04:47 PM
>Hello list,
>
>Thanks to those that helped me with my last question :-)
>
>I have a IBM ThinkPad 390X (2626MOU). That is working fine >with RedHat
>6.1.
>
>To maximize battery life I understand that it is good idea >to drain the
>battery right down to the point that the computer must turn >its self
>off. Does any one know of a safe way to do this while >running linux?
>As I am sure you know, if you do this now your hard disk >will not get
>cleanly unmounted and fsck must be run next time you boot. >Not having
>dos on my hard disk I am wandering if there is a way to >perhaps remount
>the root partition '/' as read-only when the battery gets >down to say 1%
>and unmount the other partitions. I believe this would >allow the
>computer to run till it was forced to turn off do to >insufficient
>battery power. I think that doing this manually would be >the only sane
>solution.
>
>If anyone knows how to do this or has a better suggestion >pleas let me
>know. I kind of think that someone should sell a battery >discharger.
>
>Any thoughts
>Mohrgan.
Well, this all really depends on whether you have a NiMH or Li-ion battery. NiMH
batteries suffer from the so called "memory effect" were repeated charging and
discharging to a common point, say 50%, reduces the future ability of the
battery to discharge below 50%. This occurs, as I recall, because impurities
build up a layer on the battery plates preventing the proper exchange of ions.
Lithium ion batteries, on the other hand, do not noticably suffer from a "memory
effect". Discharging fully this type will actually reduce the overall usefull
life of the battery, typically about 400 full discharge/charge cycles or 800 1/2
cycles. In short, if you have LI-ion don't unneccessarily discharge them as
you're only burning lifetime.
Personally, I never worry about a battery going dead while I'm in Linux. I have
a "save to disk" suspend partition set up and the BIOS will automatically issue
a system suspend when the battery drops to 2%, which APM faithfully picks up and
prepares for, leaving just enough power to save everything off to disk. You
might want to see if you can do the same and just let the machine run until it
gets critically low and then let it suspend and swap the battery.
Adrian
