This is not the problem in this case:
If I turn off the phone and rurn it back on WITHOUT entering the PIN it will charge to 100% if plugged in.
I got a replacement battery from HTC Support and it acts exactly the same way.
I am quite sure it's some sort of 2.2 misbehaving....
Anyways, I have come to terms with this as it seems it is only the readout that is screwed - the actual battery capacity seems to be ok.