Battery life on e6400

Ok. Going from BT off to on cut 2 hours out. Does that sound right?

 

Oh don't worry. When I plug my wireless Logitech mouse (VX nano) I also use about 2 hours of battery life, it's on 2.4 GHz encrypted wireless system. These things eats battery quiet a lot.
You SSD helps a lot on your battery life.. I have 7 hours and half using my 5400RPM HDD

If you do "Fn + D" (that will shut-down the screen until you press any key or move your mouse), wait a few minutes and youshould see your battery life in the 10-11 hour+ range.

Display, BT, wireless USB devices, optical drive (when at work), really eats your battery.
Then it's HDD/SSD, then GPU, then CPU, then motherboard, speakers, and the rest.

 

I discovered a couple of years back that Bluetooth (like Flash) does nasty things to the battery life. IIRC, it is not the direct power consumption but the indirect effect on CPU activity.

Look in Performance Monitor (Start > Run > Perfmon) and add a counter for the %C3 Time (this is indicative of the CPU low power sleep states). See how it changes with BT on and off. I am looking for a %C3 under light usage of 90% or higher.

Edit: Here's a couple of screenshots showing the time you should be aiming at (in the optimistic moments) plus a perfrom graph.

I've just treated my E6400 to a Samsung SSD (a slightly early birthday present) and it definitely helps with the power consumption. The 12 hour prediction is for minimum brightness, no web browser open, no wireless, and the extended battery options in DCP enabled (except for reducing the refresh rate). Running Firefox with about 30 tabs open drops the projected run time to about 10 hours.

Real-life usage with bursts of CPU activity will reduce the total run time, but as I type this the power drain is around 8W (it bounces around in the range 9W to 9W) which is consistent with getting 10 hours from the 9 cell battery. The display brightness is a usable 2 steps above minimum. Pushing that up to the dazzling maximum increases the power consumption to around 12W and the projected run time to below 7 hours. The Mobilemeter plot shows how the power consumption jumps around (that graph has one data point every 6 seconds).

John

 

I never got this "Fully charge capacity" How can it be fully charges if the "current state" is way over it.
This is what I have under Vista 64-bit:

 

My interpretation is that the "fully charged" capacity is the effective capacity.

The "remaining capacity" seems to match the "design capacity" and, when charging stops, the battery reports this charge level. If you pull out the power plug and watch the numbers, you will observe that the reported charge level quickly drops to the "fully charged" value and then declines gradually.

On this basis, the capacity of your battery is now down below 62WHr.

John

 

Wow, my battery is a 9-cell 85WHr, with only 28% ware level. Is it faulty? or is this normal?

 

How old is it and do you use it on a daily basis? That wear level will have progressively increased from somewhere close to zero.

It may, in part, be caused by a cumulative calibration error which you can try to reset by doing a deep discharge (disable the critical battery action in windows power management). If that doesn't work, then you might want to ask Dell if they will replace it.

John

 

So based on what I read here. It's not recommended to use BT mouse.
What about other wirless mouse, They also not recommended for saving battery?

 

The battery dates from December. I have been using the system everyday during university time. Summer it's at home plug-in. My last calibration was in end of May, when my university semester was well finished. I think the problem is that I use Win7, and that screws up the battery calibration as it uses more power due to the lack of drivers over Vista.

 

To really save battery, use the provided build-in mouse. Else a wired mouse for laptop. A proper laptop 2.4GHz mouse should use less battery but not by much.