On my prior phone I used a USB 2.0 compatible device charger from Griffin. It has an LED on it, that is green when no charging current is being pulled from it, and red when a charging current is being pulled from it. Using this charger, I figured out RIM's Blackberry (my prior phone), will charge for several hours more, after the blackberry indicates it is done charging.
I was interested how the HTC Rezound would do, so I tried charging it on it one weekend, and an overnight and half a day later, the LED was still red. The phone was in sleep mode, so the screen was off. Usually enough to get a good charge. I tried it again and had the Rezound powered off. After more than 12 hours on the charger while turned off, the LED was still red.
I warranty swapped the phone figuring it was a defect.
I tried it again today, a different HTC Rezound, and I used the Griffin USB 2.0 compatible charger I got for my wife. Exactly the same as mine. I tried it again. It should already be fully charged, so I powered it off, and pulled the battery for a couple seconds, and put back in the battery, making sure I did not turn the phone on. The LED was green. For about a second. Then it turned red. After two different phones, and two different USB port chargers (but same MFG and model), I have to conclude the HTC Rezounds are consuming enough power when turned off (not sleeping, but powered off), that they actually pull a charging current when you plug them in.
Anyone else run into this, or have some information that might explain what is going on in the phone?
I should mention I have not tried a replacement battery yet. That will be the next step. Repeat the test with a new battery. The battery I am using now though has only been actively used in a phone for a couple weeks or so.