Surface Pro 3 short battery life

No, I left the brightness alone.  In fact, the only thing I did was shut off sleep mode when on A/C.  Now, this is the i3 model and the CPU uses a lot less resources than the i5 and i7.

The battery will click down when doing a lot of web browsing or listening to music.  Did not pay much attention to video playback but did watch one movie and one TV show and the battery level barely moved.

It is possible that I may have a rare machine that has no defects or that the i3 models have no issues compared to the i5 and i7 models.

As for 8 or 9 hours of use; I think that was from one test bench model (i3) with nothing attached to it and all they did was turn it on and clocked it.  Not connected to the Internet either.

Only an ATOM processor could be productive and provide a 9 hour battery life.  I have the Asus T100 that gets 11 hours and I tested that 4 times and it actually does it.

I would say that it would be normal for the i3 to get about 6 to 6.5 hours, i5 about 5 hours, and the i7 about 4 to 4.5 hours with normal use and being conservative.

Now, if you shut the brightness down too much, it becomes not useable in a normal sense.  It is actually not worth it and the light panel is LCD and uses very little power.

Now, I did not detach the keyboard/cover and tested the duration of the battery that way.  I probably could get more by doing that.  I also don't use OneNote and barely use the pen at all.

My email is POP3 so it pings the server in milliseconds and should not even register power usage.

So, if I did go more conservative, I could probably stretch the power consumption to 7 to 7.5 hours (possibly).

Just to add another data point, I have the i5 256, and I'm also getting around 5 hours of web browsing, office, etc. To be a bit more concrete about it, here's a screenshot of my batteryreport:

I've had this Surface unit for about 5 days.

The weirdest thing to me is that the battery is drained quite fast on standby. It usually loses around 20% of battery in 4 hours of connected standby.

With the i5 and after the latest updates, 5 hours will probably be correct for that model.  I had guessed that the i7 model would get around 4 hours.

I don't think there is anything else you can do to increase that.  However, there was a thread regarding the video driver and an update for it from Intel.  If it is true and that update ends up in Windows Update in the near future, that could improve the over usage of power the tablets seem to be doing.

My i3 is a lightweight and had expected it to get pretty good battery life but six and a half hours seems to be the tops.  Don't know where Microsoft came up with 9 hours for any model.

That must be with no attachments and just turning the machine on and let it sit on the lock screen, maybe!

Setting brightness to minimum and turning Wifi and BT off.

I have i5 256GB version. The battery life is from 4 to 5 hours, when device is used for internet browsing with occasional youtube video watching. I made sure no resource-heavy background programs are running (CPU activity was varying  4-10%), the battery was fully charged and that the screen brightness was around 30%.

These results reported by me and others are obviously far cry from 8-9 hours of battery life that has been advertised!

With the i5 and after the latest updates, 5 hours will probably be correct for that model.  I had guessed that the i7 model would get around 4 hours.

I don't think there is anything else you can do to increase that.  However, there was a thread regarding the video driver and an update for it from Intel.  If it is true and that update ends up in Windows Update in the near future, that could improve the over usage of power the tablets seem to be doing.

My i3 is a lightweight and had expected it to get pretty good battery life but six and a half hours seems to be the tops.  Don't know where Microsoft came up with 9 hours for any model.

That must be with no attachments and just turning the machine on and let it sit on the lock screen, maybe!