I was in Scotland last week having a wee break (stalking

) I charged my I Phone the night before as I always do. Whilst on the hill, around noon, I made a call and the phone worked perfectly and there was 85% of battery power available. A few minutes later, I went to make another call but when I tried to turn the phone on, it remained lifeless. I could not get any reponse from the phone whatsoever.
Upon getting back to the hotel, I tried to recharge it but the phone refused to light up. The following morning, after having been attached to the mains for 15 hours or so , it still showed no sign of life. I disconnected it from the mains, and tried to turn it on again. Strangely it powered up with a completely empty battery and a message requesting that the phone be charged. I reattached it to the mains and after 10 minutes, it started to recharge.
Has anybody else had a problem like this? I will be visiting the phone store later today.