I finally surrendered to the fact that my phone needs to be charged around 3-5 PM every day and bought a fantastic case called Third Rail. I can carry an extra charge in my holster and just snap it on when I need it. I don't always have my ZaggSparq with me, so this is working out very well and I'm no longer stressing about battery life.
I had this problem when I downloaded the latest software update; my phone started draining away as fast as sand through a timer. I searched forums and found an interesting cure. The writer suggested that the phone was working though something when I downloaded the software, and that it was now caught in a loop, constantly trying to finish the task. They suggested it was probably email related and to backup email/contact info and then remove all email and icloud apps, and reinstall them. As soon as I removed them my phone was back to its former self. It was at 80% and the next morning had only lost 1%, to 79%. I loaded the apps back on and everything is fine, and back to 2 full days of use before charging - it was just 2 hours at worst.
I can report the same experience. Right at about 35% too. I'll be snapping a photo for work, or possibly shooting a video (rarer) and the screen just goes black. Hop back to my truck, plug the phone in, power on and she's at 35% or thereabouts.
Not happy about the situation, but glad to learnt that mine is not the only 4s experiencing this anomaly.
Was thinking about replacing the battery, but now I'll hold off through another update or 2.
Thanks for your post.
I went to settings and turned off icloud and my hotmail email accounts. Then charged it up, turned the phone off and on again and it was fine. The next day I rather nervously turned the accounts back on again and the battery has been fine ever since. I don't have many apps on my phone, but I suggest you start with these two and if that doesn't work, look through the others if you have lots of apps.
I no longer have problems with my phone's battery life after being plagued with them for a long time however I can't recall the exact point at which it all worked
removed skype entirely
notifcations on only for:
fetch new data - 15 mins, push is OFF