My 3GS battery timings
Like many other people, I have been a bit dismayed to find the battery life of my new 3GS to be substantially less than my treasured 2G. I've been keeping fairly accurate timings when the battery hits the 10% warning, since purchased on release day:
Standby hrs / Use hrs
-------------- Purchase
20 / 2:00
21 / 4:00
19 / 4:15
24 / 3:34
26 / 4:00 *17%
21 / 3:43
------------- full restore recomm. by Apple support
21 / 4:26
------------- push off, fetch 30mins
34 / 5:33
22 / 3:46 (v bad coverage area)
*This measurements were taken before getting to 10% battery warning, to the numbers specified.
My usage pattern is what I'd classify as "light". About 50% of the use time is playing music with the regular iPod app, the rest on the web (50/50 WiFi and 3G). Not really any CPU-sapping 3D gaming or the like.
So my takeways are that I too felt like battery performance improved over the first few charge cycles charges. This gels with stuff I have read about lithium-polymar batterys that work best when "the electrons are kept moving", i.e. they actually benefit from light use (although it ads to the death-march cycle-count). It had been in a box in China unused for the last 2 months probably.
Although I am only on my first cycle with push off, I am seeing about 30% longer life. And my usage was a bit heavier this cycle with less music.
Now here's where the conspiracy starts. I use push for Google calendars and contacts only, through the official Google activesync implementation. Previously I was using Nuevasync for push Google calendars and contacts on my 2G, and I did not notice any decrease in battery life when I first switched to it a few months ago.
I am wondering if Google's implementation of activesync, for either the calendars and/or contacts is way too "chatty", perhaps pushing contact info for every piece of mail I get or something? I plan to do more testing with push enabled for just one of those services to see.
I had originally planned to return my 3GS for replacement by today, it's 14-day anniversary, but it looks like I won't get to it, so I think I will hold on and do some more testing. I'd hate to have to put another bloody invisi-shield on the new one...
Cheers