+1,
I would definatly take a hard look at that battery, Falling from 90% to 5% in 2-3 minutes is not normal, I'm guessing that is the stock NiCd battery that came with the radio. If you never ran it down past that point (or cycled it) before it may have deveploed a memory issue and once it got low, just dropped off the map.

I'm curious, How old it the Tx battery?