I have never had the phone with a SIM/contract. I bought it off someone who's contract expired for the SOLE PURPOSE of using it as a PMP. I had read several reviews comparing it to the Sansa line, the Zune family, and the Cowon X7, all things I was considering buying. Most of the testimonies said that the SGS was superior, so I went for the buy. $100 for a like-new SGS seemed like a steal to me.
With airplane mode on, with moderate wifi usage (a few hours of IM+ and Face Book) I have never run the battery dry, unplugging the phone at 6:30 AM and plugging it back in at 11:00 PM with 30-40% remaining.
I'm using CM7.1 which uses noticeably more battery than Froyo does, AND my phone's overclocked. If I ever bothered with an extended battery (2600-3500 mAh), I could probably get a solid 30-40 hours of constant use out of the thing.
Quote:
Originally Posted by
Spardasieg 
I am about to jump ships to another phone service and was thinking of using this phone for my mp3 player only, thing is the phone only lasts from about 11am to 7pm and then goes dead(Light usage, maybe 10-15 mins of facebook, 2- 5 minute calls, and well thats about it). I cant really test the battery life without a sim card since I might miss calls/texts. Was your phone that bad when you used a sim? I am on 2.2 official firmware.
Not sure how to go about all that custom firmware, is it hard? Does it really help that much?