This has happened twice to my iPhone 5 since updating to 7.0.3. Both at around 30-ish percent. One time I was on the phone with my wife and it just went dead with the spinning circle then cut off.
I remember thinking WTF because I didn't get any warnings about a low battery. I tried to turn it back on and it gave me the battery icon showing red telling me to if it in. I plugged it in and within about a minute it had rebooted and went to the lock screen with 35% and charging. Again, I said WTF and chalked it up as a fluke.
Then it happened again today. Was at about 32% or so and it cut off while playing music. I plugged it in and it rebooted.
I remember thinking WTF because I didn't get any warnings about a low battery. I tried to turn it back on and it gave me the battery icon showing red telling me to if it in. I plugged it in and within about a minute it had rebooted and went to the lock screen with 35% and charging. Again, I said WTF and chalked it up as a fluke.
Then it happened again today. Was at about 32% or so and it cut off while playing music. I plugged it in and it rebooted.