Extra battery: Li-Polymer or Li-Ion 9-cell?

[Mofongo]

So I held off getting an extra battery for my T42 until I had used it awhile and gotten a better feeling for what I need. But I have had my Thinkpad about 2 weeks and I still am not sure which one to get.

Currently, it has the standard 6-cell battery, and I get about 3.5 hours of usage out of it with all the power-saving features enabled (which, for once, is about what the TABOOK says). I like the idea of the Ultrabay Li-polymer battery because most of the time I am wandering around away from a power source, I do not need my DVD/CD drive, so the Ultrabay battery provides a great way to have the weight and form factor of the unit stay the same but increasing my battery life 33%.

On the other hand, I do a lot of flying, and some of it is trans-oceanic. Although aircraft are getting much better at having the laptop power plugs, many of the ones I end up on (and especially, it seems, the transoceanic ones) are too old (I have always found this bizarre...here I am on a $250 million aircraft with 4 super-high-wattage power generators within 100 feet of me...and I can't get an extension cord??) Anyway, I am lured by the 9-cell because it in combination with the 6-cell will give me 9.25 hours of battery life (with one battery swap). I also attend conferences where they often have wireless availible but not reachable power sources. So 9.25 hours would let me last all day at the conference.

So my questions is should I get the Li-polymer or the Li-ion. They are about the same price. I would appreciate feedback from people that have either the one or the other (or both) as extras and how often they find themselves using their extra battery.

Thanks,

Mofongo

[ryan]

Who's your source for the 33% gain in battery life with the Li-poly? I know the tabook says that it's 33%, but I was wondering if you checked somewhere else? When I called IBM I was told that the Li-Poly offers just as much battery life as the normal 6-cell.

[Mofongo]

Oops..I should have said 50% gain. The Ultrabay Slim battery is 3-cells (Li-polymer and Li-ion have about the same capacity per cell). So basically, a 6-cell Li-ion plus the Ultrabay Slim battery gives you the same lifetime as a 9-cell...very roughly.

Here is a link to some info on the Li-polymer battery. They still do not give the actual capacity, but say that battery life is "up to 2 hours". The highest I have seen on a T4x with a 6-cell is a little over 5 hours, so the estimate is actually a bit less than 50%.

http://www-307.ibm.com/pc/support/site. ... MIGR-46436

Can any Li-polymer owners out there give us some real-world numbers??

Thanks,

Mofongo