X220 vs T420 battery life

Can't decide between the X220 or T420 but battery life is going to be extremely important to me. It seems from what I've been reading, both of the laptops have identical battery life. Does anyone know the battery life of both the laptops using just the standard 6 cell battery?

Also it seems that Lenovo discontinued the slice battery for the X220? Is that true? Its going to be a pretty big deciding factor if it is.

 

Battery life is not identical between the two.

My X220 with 9-cell gets around 12 usable hours per charge.

A T420 will get probably around 7-8hrs.

 

They run on the same components, so the battery life should be similar. The only different really would be the screen (14" vs 12.5"), but I think the T420 has a slightly larger 6-cell (in WHr).

 

I see, but how sure are you of those numbers. From what i've been reading, the X220 gets 6 hours on the 6 cell and the T420 also gets 6 hours on the 6 cell.

 

On the x220, the 6 cell will get you about 6-8 hours of real world use. The 6 cell on the x220 is rated for 62watt/hours. So, if your usage comes in at about 10watts an hour, You'll get about 6.2 hours of usage.

 

It should be similar. My W520 can get me 8.5hrs surfing the web on WLAN on a balanced profile (no Flash). So, I have no doubts that a T420 can do around 12hrs given the same ratio to the rated battery life.

 

Found something interesting about the batteries. It looks like the 29+ for the X220 is rated at 63Wh and the 55+ for the T420 is rated at 57Wh. So it looks like the X220 should technically have a huge advantage in terms of battery life over the T420.

 

When doing a lot of web activity over wifi, including a lot of downloading, I regular see about 8 hours life shown. I usually put power in after 5 hours or so. No point in running the battery empty.

 

Is that on the X220 or T420 with 6 cell?

 

T420 9-cell.