[ltp] T60 battery

[Theodore Tso]

On Mon, Nov 27, 2006 at 08:08:54AM +0100, Laurent Gilson wrote:
> The pendrive wins. It may wear out quickly since pendrives can only take  
> XY writes before giving up. But the number of cycles is very high for  
> quality flashmemory and even with saving every minute it should last years.

Keep in mind though that on the T60 when you enable the USB, this
enables a lot of other USB devices (fingerprint reader, synaptics
touchpad, etc.) which draw a lot of juice.  If you rmmod ehci_hcd and
uhci_hcd, you will see a pretty big power drop.  So what I normally do
is use a mail reader like mutt, and make sure I've read in my entire
mailbox at startup, and then let the hard drive spin down and just
read e-mail without letting the hard drive spin up.  When I'm done, I
save it all out and let the hard drive spin up briefly.

There are some magic bind/unbind hacks if you are using the latest
kernels that are supposed to allow you power down an individual
internal USB device without needing to bring down the entire USB
subsystem, but it's all very manual right now and a pain to do, so
normally for me I just make USB an all-or-nothing thing....

Also note that you need to be careful about how much you spin up and
down your hard drive.  I used to use very aggressive hdparm settings
to spin up and down my hard drive, and I found that after 6 months, I
had spin up and down my laptop hard drive a little over 206,000 times
--- and the hard drive is only rated for 600,000 head load/unload
cycles.  So I had chewed up one-third of my hard drives lifetime very,
very quickly.  So I've since disabled the hard drive spindown unless
I'm really desperate for extra battery lifetime.... not that replacing
the hard drive is that expensive (if you use a generic hard drive,
it's roughly the same cost as replacing the battery), but the risk of
data loss since the last time I backed up my hard drive is the much
higher potential cost.

Regards, and good luck!

						- Ted