ORIGINAL: RCKen
No, it won't work. Most wall wart chargers that come with your radio have an output voltage of 6 volts. This is what is needed to fully charge a 4-cell (4.8v) pack. These cells are fully charged when they are at 1.5v, so 4 cells times 1.5 volts/cell equals a total voltage of 6 volts. To fully charge a 5 cell (6 volt) batter you are going to need a charger that can put out 7.5 volts in order to fully charge that battery.
Ken
That's interesting because I have been using the wall wart that came with my radio system to charge a 6V battery. I bought one of those Hobbico Hydrimax batteries and it even says in the instructions that you can use a standard wall charger.
Based on what you are saying I assume it may not be getting a full charge but I have been doing it this way for 2 years and have never had a problem. Maybe I am just very lucky