[ltp] Running with line power and no battery

[David A. Desrosiers]

On Thu, 2008-02-28 at 11:53 -0300, Henrique de Moraes Holschuh wrote:
> Even when the laptop is in my desk, which has a damn good UPS feed, I
> still keep the battery inside because I often want to sleep-to-ram and
> remove the laptop to work on another part of the house (and I do NOT
> trust sleep-to-disk).

I've had Thinkpads consistently for the last 10-12 years, and I've tried
two distinct usage patterns, both of which seem to have a very negative
effect on battery life: 

1. Plug in the laptop with the battery attached, use it until the
   "Battery is fully charge" alert comes up, then disconnect AC, and
   run exclusively on battery. When the low-power alert comes up, plug
   AC back in and continue to work until the laptop battery is at 100%
   charge again. 

   Lather. Rinse. Repeat.

   Time and time again, across about 7-8 different Thinkpad laptops,
   this has proved to "kill" a battery before the initial warrantee
   period of the battery expires (i.e. no longer holds a charge). A 
   call to IBM for a replacement battery, and you can start all over
   again. 

2. Charge battery to full while on AC, then remove the battery, working
   only on AC power. When you need to disconnect from AC (or work
   mobile), plug the battery in and use until the low-power alert comes
   up. At this point _switch_ the battery for a full-charged second
   battery.

   Take the first battery and use the "Battery Rundown" tool to fully
   drain the battery (usually will provide at least 1 more hour of
   "life" past the low-battery audible warning alerts). I've usually
   done this before the end of the day, so I can then plug the laptop
   into AC with a _fully_ run-down battery, to charge it to full by the
   morning commute outbound.

Both of these approaches seem to rapidly kill Thinkpad batteries (direct
from IBM, not third-party replacements). 

I spoke to an IBM tech at one point about #1 above, and he recommended
that as the best way to ensure you don't "prematurely age" the battery.
He said that keeping the laptop plugged in while the battery was fully
charged was a bad idea, if I wanted to ensure long life from that
battery. My own tests confirm and validate this.

> My 9-cell and bay batteries are at 95% of their design capacity after
> two years of use (proper storage at 10C).

10°C is 50°F... are you storing these in your refridgerator in a ziplock
or something? Keeping them in a metal container in your basement or
cellar? 


-- 
David A. Desrosiers
desrod@gnu-designs.com
Skype...: 860-967-3820