Issues with Ultrabay battery - does your T60 destroy them?

[syncrotic]

I have a T60 that I use on battery power almost every day with a combination of the six-cell Li-Ion main and the Li-poly ultrabay batteries. The latter of these two has caused nothing but problems for me, and I think Lenovo's poor battery management strategy is to blame.

The basic problem is that, when discharging, the laptop will completely drain the Li-poly battery to zero before starting to drain the main Li-ion. This means that, in the course of your normal day's computing, you'll fully drain the poly battery every single time - even if you only use half the capacity of the two batteries combined.

I don't know if this kind of deep discharge / full recharge cycle is damaging to Li-poly cells in general, but my experience certainly seems to suggest it. After my first battery was reduced to half its rated capacity in just a few dozen cycles, I called up Lenovo and got a replacement under warranty. Well, my second battery is now at 54% of its original rated capacity after about four months and 65 cycles. That means that, under typical usage, it's now good for a whole 45 minutes.

Further suggesting that Lenovo's design is to blame: Dell Latitude notebooks will discharge the li-poly secondary to 10%, then switch to the primary. They drain the li-poly to zero only when the primary drops to 10%. The D610 that I used to own was at ~85% of its original capacity after eight straight months of daily use.

Are there any T60 owners with ultrabay batteries and similar experiences? Or opposite ones, for that matter? Have I uncovered a flaw in the design of these machines, or am I just the recipient of two bad batteries?


Note: the batteries are never subjected to more than room temperature - the issue is not thermal damage.

[stephenaron]

I have had IBM replace the ultrabay battery twice since i bought my T60p. Every 6 months i call them and tell them that it isnt holding much of its charge. They send me a new one, no hassle.

[abu_sme]

I agree that it is a little bit insane in my opinion how it works. I don't have the li-pol battery, and I have been hesitant to bite for this very reason. I am not overly impressed with what I have read. It seems like one of the most logical solutions would be to use the main battery and then supplement it when it gets low by insterting the extra battery. This may or may not be practical as you might not want (or be able to) carry the other battery seperately. I know that I would be unable to, as I keep my TP in my hands all day, and NEVER put it in a case.