I have the same issue here. Got an OTA update last week, and ever since my Galaxy s2 will randomly shut off during use. When I turn it back on it has 1-5% battery left, even if it was fully charged before the shutdown. It creates a random dip in my battery life. If I plug it in and reboot, it will bring the battery % back up significantly. Contemplating a factory reset as the problem keeps happening more frequently.
If you're willing to try one thing you could go into recovery mode (Hold Vol Up and Power for about 15 secs... you'll see the indicator light flash blue, the battery show and then recovery appears.) and try to clear the cache only. This may help resolve your battery problems. If not definitely consider the factory reset... as well as installing FH13 updates if not done so already..
After having this issue for a couple of weeks, I started to notice my battery becoming physically swollen. Of course, that is very bad. I took it into the Sprint store and they gave me a new battery. Completely fixed my issue, and this battery lasts quite a bit longer as it is new and healthy. I would recommend anyone with this power issue to check their battery, and look to exchange it for a new one.
Great find. I'm having battery loss/reboot issues. I would take the battery out for a minute and then put it back in and it would work for a while. I also noticed in passing that it was becoming a little tedious to put the back cover back on. I read your post about the swollen battery, and I noticed that's why it's harder to put the cover on! I would have never thought about that had I not read your post. Thanx. lol.
There are a couple of different problems it might be.....one is the battery life and the other is the power button is off the track and keeps turning the phone off and on. That happened to me. I took into the Sprint repair store and after looking at the phone for 5 seconds, they said it was because I had water damage to it. I had never imersed it in water or anything and the last time it was a little wet was months before the problem started happening. They handed it back to me to say I needed to contact Sprint for a new phone. I looked at the power button when I got home though and it seemed to be stuck.....so I took it apart after observing what the tech did and found the power button to be off track. Viola, all fixed.
My wife and myself are having this sample problem. We both have the GS2, and both randomly shut off, and have massive instantaneous battery drops. My wife is on call for her work often, and it is unacceptable for her phone to shut off, only to be restarted with zero battery.
I have the same issue with the phone restarting. It has happened 3 times this morning already. I have updated the phone, have not installed any new programs although I have downloaded some music from the same source I have always used, we have cleared the cache. It has been doing this off and on for the past couple of months, but this is the first time it has done it 3 times on the same day. I have a full charge on the battery. This is very annoying.
I *think* I found the problem that drove me crazy with my Sprint Galaxy S2. I got a new battery ($7 on Amazon) AND turned off the Sprint Connections Optimizer. My first battery got ruined after an update that installed this optimizer (which SOUNDED like a great idea). The battery was swollen, and my phone would shut down all the time and not restart unless I plugged it in (REALLY convenient for a mobile phone!). I bought a new battery to see if that was the problem but it kept shutting down. I turned off the Connections optimizer under Settings > Network settings. It's been a couple of weeks and to my knowledge my phone has not shut itself down at all since then. It actually holds a charge again. I just have to manually turn on wifi or 4g when I want to. Crossing my fingers that's really it, but it's worth a shot if you're in the situation I was with an unreliable phone and a year left on your contract. If this is really the problem, sprint needs to fix this optimizer thing, which I think is what fried my battery.
I'm having the EXACT same problem. It's driving me nuts! Battery can be almost fully charged & it shuts down & won't restart until I plug it in. Once I plug it in at first it says the battery is at 1 or 2%, then about 5 seconds later it jumps back up to around 40 or so.
I just tried clearing the cache as someone suggested. If that doesn't work I guess I'm off to the Sprint store. It's very disappointing.
We have 4 Galaxy S2 Epic phones and two of the four have had this problem. My dad's phone was first. They took it in and the tech told them there is a prong that is bent the wrong way in the charging port and it is causing a short in the phone. They sent in the phone to repair, it cost $50.00 with insurance. Mine is now doing the same thing. I tried all of the suggestions listed here and was speaking with my mom when I found out about my dad having the same thing. Just thought I would share since there seems to be a lot of people on here having the same issue.