to all those with a 7cell battery

How many watt hours are you getting?

my 6 cell is correct in that 10.8 volts X 5.2 Amp-Hours = 56.16 watt hours

however my 7 cell shows (in power manager) about 65 watt hours but

14.4 volts X 5.2 amp-hours = 74.88 watt hours


upon further inspection, I noticed that the 7 cell has both 10.2 & 14.4 volts written on it

the only way it seems to make sense is if you average 10.2 & 14.4 volts to get

(10.2 + 14.4)/2 * 5.2 amp hours = 63.96 watt hours

how many watt hours am I supposed to get with a 7 cell battery? what numbers are other people getting?

I have a t61 14.1 inch wide (model 7662)

thanks for taking the time out to respond to this

 

That sounds about right. After about seven months of usage and almost 100 cycles, I'm at around 68Whr.

 

Don't tell me that kind of depressing news Arkit3kt! I want my battery to last...forever...like a diamond from DeBeers.

 

so a brand new 7 cell is supposed to show 65 or 75 watt hours?

 

It has always seemed odd to me how adding one cell to a 6 cell can increase battery life by 33 percent. I guess I always thought it had something to do with wiring (series vs. parallel, etc.), or different kinds of cells or something. But then why would lenovo market the batteries by the cell count if the cell count doesn't correlate well with the battery life? The whole thing doesn't make much sense to me, so I hope someone can explain this.

 

A 9% decrease in battery life in half a year is really good.

Brand new is about 75Whr.

 

While we're on the subject of batteries, hopefully this isn't too OT.
What's the largest battery that won't stick out the back of the T61P 15.4?

 

6-Cell I believe.

 

I may be thinking of the wrong thing but I remember that the reason they changed from the 7 cell to the 9 cell was because the 7 cell doesn't last as long (lifetime-wise). It has something to do with the fact that the 7 cell has higher operating voltages and how that works in with battery degradation. Someone correct me if I'm wrong.

 

that's odd, i have two new 7 cells and both show 65

 

I have a 7662 too with the 7-cell battery. "Design capacity" is 65.52 Wh, and after 7 months and 30 counts the "Full charge capacity" is 65.00 Wh. I'm not sure I remember well, but I think the remaining capacity used to be in the 70s when the laptop was new.

 

ahh i see, thanks for pointing this out. newer models (after the 7662) must use different batteries...