radio charging time??

[badas]

Got a BT Freeway FM radio and i charged it the other day in its dock but the red light just stayed on for agers.

So i disconnected the radio from the charging dock and it said the battery was full..... Turned hte radio on a day or two later and the battery was dead :S i had not used it since charging.

So its back on charge again now and its been on for an hour atleast but the charging light (red) is still on and i don't know if its ment to go green when finished?

How long should this charging take really?

ty