I initially bought it with a big 8 cell battery which feels quite okay. But it just has around 5-6hrs runtime...
It's still much more portable and lightweight than a Z61e with 9cell battery and a T42 (even with a normal battery).
I was asking about the extended life battery that docks at the bottom, and how much it adds up to thickness etc. in practical terms.
(this one: http://shop.lenovo.com/SEUILibrary/cont ... de=40Y7005
btw: My 8 cell battery doesn't wiggle at all, it is no problem to grip the laptop at the battery. It even feels quite comfortable to hold it there...
I just ordered the extended life battery, I could get it quite cheap here.. I will report back here about my experiences!
I have a new X61s that got from the Outlet; it came with the enormous 8 cell battery. I also ordered one of the slimline 4 cell batteries (that was a "scratch and dent" one from the outlet for less than $40), and an extended life also. The extended life battery (also scratch and dent, not as good a deal, around $80) was old and in unacceptable condition; I sent it back and then ordered a new one under a deal on an affinity site, and that extended battery arrived yesterday.
The extended battery has about the same charge capacity as the 4 cell slimline (~28 Wh) which is around 25% less than the regular small battery that can be used with either the X60/X60 or the X60s/X61s. The large X6x battery (which can also be used with the extended battery), according to power manager software, has about the same runtime as the combination of the slimline and the extended.
With only the slimline battery attached, the X61s has very nice tapered lines, with an appearance and weight not much more than a "netbook." With the extended battery the laptop has a much thicker back than its front. With the large 8 cell battery the depth of the laptop is much extended and the laptop no longer has any apparent advantages in form factor over the standard X60/X61 (non-S models).
In summary, If I'm going to use the X61s mostly with the charger, as I usually will, I'd much prefer the 4 cell slimline. If I was regularly going to use the laptop on battery power and for periods of time longer than an hour, I'd use the 8 cell. If I was traveling and would use the machine both on battery and AC, then I'd maybe bring along the extended along with the 4 cell slimline. For maximum amount of time away from an AC outlet, I'd use the 8 cell AND the extended battery, however the form factor of the laptop then changes completely and it becomes heavy and a bit unwieldy.