mthuhn - Having a device that power cycles is a pain we do not want you to have. We can work together and fix the issue you are having. When did the issue begin? Does this only happen when your battery is drained? Are you using the original charger?
Follow us on Twitter @VZWSupport
If my response answered your question please click the �Correct Answer� button under my response. This ensures others can benefit from our conversation. Thanks in advance for your help with this!!
I had basically the exact same issue! My phone battery would say there was roughly 3-5% battery left, then go into a cycle where the phone would keep rebooting. As time went out it would happen when the battery said there was 10%, 15%, 30% and up to 50%, but would last second drop to 2 or 3%... So I would take the battery out, but it back in to stop the reboot cycle, plug in the charge and the phone would read it was it 50% or whatever percent still. Very frustrating!
Then I called the jokers at customer support and they remotely ran some tests and asked some questions. The first guy didn't know what he was talking about, so I hung up and called again. The next person asked the same questions, ran the same tests, then said they would ship me out a new battery with overnight shipping. After a week and I had not received it yet, I called back and went through the same fun process again. They said the first guy never ordered the battery and sent another one. Waited another week, still no battery... So I called again, went through the same process again, and this person said the battery was on back order, so they said to order one off amazon or something legit and send them a picture of the receipt and my account would be comp'd the price of the battery. I think mine cost like $18...
After I finally got the new battery, I didn't have any other problems with the phone rebooting constantly. Although, I did have my phone replaced a few months after that because the charging port was bad, which was covered under warranty.... That process was a lot easier though! haha
I hope this helps!
Short answer, you need a new battery. Why the phone doesn't realize that the battery performance has degraded and adjust its meter accordingly is a question for Samsung. I first noticed mine when sour when it said around 20% remaining but within a minute or two would drop to 15, then 5, and begin boot-looping. The battery is dying before the phone realizes it is low and thinks it still has enough power to boot. Eventually after enough failed boot attempts it will think there is something wrong with the phone & indicate that the phone's software needs to be restored (which it doesn't). If you watch it you will recognize the low battery threshold and know that is the true zero point. My recommendation is to buy a genuine replacement battery from Samsung (my local Verizon shops do not carry them in the store & the associates directed me to Amazon for a replacement). I bought what I thought was a Samsung battery on eBay, but it does not have an NFC coil and whenever I take a photo with the flash on the phone shuts off & I have to pull the battery.