Help HTC Wildfire battery issue

Wife's phone keeps discharging completely overnight when not used at all. Tried all batter monitoring apps and found some wakelocks, but could not isolate which app, so reset to factory settings and hoped it would be fine, but last night same thing again.

Battery health is showing as 100% though, so could it still be a battery issue?

I would like this phone to last a couple of months, so that she can take over my S3, and I can get something new - maybe the Note 2 or S4.

El Presidente

Beware The Milky Pirate!
If the issue persists after a factory reset, it's most likely hardware. You can pick up batteries relatively cheaply on Amazon so if you're only looking at using it for another couple of months, there shouldn't be an issue using a cheap one.

If another battery doesn't sort, it's obviously the phone.

Alternwtively, poor signal can have a massive impact on battery performance, are you aware of any issues in your area at the moment?