[ltp] Don't buy the IBM 8K8190 / 8K8191 Ultrabay Slim Battery.

[Thomas Roessler]

Executive summary: Don't buy this battery. Buy the 9-cell
Li-Ion battery instead (that's the one that puts the bulge on
the back of the Thinkpad), it's the same (or even more) bang
for the buck, but keeps the Ultrabay free. Only buy the 8K8190
(aka 8K8191) if you need to squeeze every minute of
battery-powered independence out of a Thinkpad.

For the record: I fell into an IBM marketing trap here.  The
ultrabay slim batteries for the T series thinkpads *do* *not*
double the capacity of the machine, despite the fact that

  http://www5.pc.ibm.com/europe/products.nsf/$wwwPartNumLookup/_08K8190?OpenDocument

talks about "doubling" the working time:

  Install the battery in your ThinkPad's Ultrabay Slim or
  Ultrabay Enhanced bay. Working in parallel with the standard
  system battery, it can double your 'unplugged' time and
  reduce the inconvenience of needing to stop work to switch to
  a new battery.

(The Ultrabay battery that I had in a previous R40 did indeed
double the working time, but it does not fit into T series
thinkpads.)

Here, however:

  http://www-307.ibm.com/pc/support/site.wss/document.do?lndocid=MIGR-46438

the real technical specifications can be found, and it's
suddenly just "up to 2 hours without recharge" battery life --
hardly doubling the 3+ hours that I get with the original
battery. Unfortunately, I hadn't seen that page before buying
the battery.