Battery Life is weird for 4820TG

Hi all

The remaining life of my battery according to windows 7 is screwey. On average the time remaining is less than 4 hours on the lowest brightness with wi-fi on, but the weird thing is that the number remaining keeps fluctuating. I think I actually get more than 4 hours, but the windows reading will jump from 2 to 3 to 4 to 5 hours remaining as the battery life goes down.

I have already tried discharging completely and recharging, but the problem remains.

What can I do to troubleshoot the problem?

 

I don't see a problem- Windows makes a calculation based on current power draw. Power draw changes when CPU and/or GPU load changes.
If the draw increases Windows recalculates its estimate- lowering the predicted remaining time, when the load decreases windows recalculates again and gets higher remaining time.

 

I don't understand? On my older laptop Windows XP always told me how much time I had remaining and it never fluctuated like this.

If I'm doing the same tasks, I check my battery life throughout, shouldn't the time left be always less than the last time I checked?

Like I'm getting instances where it'll be 6 hours at 100% 3 hours at 95% and then 2 hours at 90% and then 5 hours at 80% how does this work? How am I supposed to know how much battery is left?

 

You know for sure only how much capacity the battery at the moment (in %).
The remaining time is an estimate based on current power draw.
Let's say you went from 100% battery to 50% battery in 3hours just reading a PDF file. So you're left with 50%- which will last for another 3h if you continue reading PDF but only for an hour if you launch a game.

Why does the prediction increase?

If you take this example the other way around- play a game first for an hour which will make the battery go from 100% to 50% and then stop it windows shows you that you have another hour (of gaming) left. Then you start reading the PDF- the power draw drops and Windows recalculates that at this rate you have 3hours (of reading) left.

 

Ah that makes sense, but let's say I'm only browsing the internet and not doing other things, shouldn't the decrease in battery life be consistently going down if I check it after an extended period?

 

A lot more consistent than if you go from gaming to reading- yes- but keep in mind that flash-heavy websites cause higher CPU utilization and flash videos may be hardware accelerated which would mean GPU would use higher clocks and voltage (in case of ATI card). Also your W-Fi card uses more power when downloading/uploading then when doing nothing.
All in all browsing this forum would result in lower power consumption than watching youtube video (both flash video and download).

There are also other windows events, virus definitions being downloaded and applied (sometimes with so called start-up scan afterwards) and so on.
If your usage pattern is pretty consistent your estimated battery run will also be consistent but it’s still only a prediction based on how much capacity is left and how much power is being drawn at the moment.

 

Oooooh I see. If that's the case how can I measure the average battery life of my notebook?

 

You may try Battery Bar. It has a statictical approach for battery life guesstimation, so the predictions are not extremely fluctuating.

Michael