Specs:

• Target: Froyo Android 2.2
• Keep screen on when plugged in.
• Release screen lock when on battery.
• Remember timer / restore after restart. Compensate for time off (if accurate).
• Change timer color:
• white default.
• orange if > 24h
• red if > 48h
• red blink if > 72h
• Email updates notifications.

And yes, the target really is Froyo Android 2.2. I like to reuse old phones as dedicated one-off appliances.