Back in 1998 I purchased a Niterider Digital Pro-6. The Lighting system worked great up until just last year. The battery pack is no longer able to keep a charge. Well, I took apart the water bottle battery and what I found was quite disappointing to say the least. To replace the batteries it would have cost about a hundred dollars plus shipping maybe, then throw in at least a week to two weeks for replacement from the factory. Anyway, to my horror there were only five 'D' sized batteries arranged just so to fit in the bottle type container. I believe that they are Ni-cads. Either they must be some special factory or industry spec'd batteries or I was really ripped off! I went to Radio Shack to find replacement batteries similiar to the ones I was replacing. I wasn't satisfied with the cheap regular ones, so I was thinking of using 7.2 volt battery pack used for radio controlled cars. Has anyone had any experience with this sort of thing or am I going to have to pioneer this thing and probably fry my headlamp. I'm a bit hesitant to do so on the account of using a higher voltage battery. Will overvolting the headlamp ruin the circuitry or processor? Also, what halogen bulb, if any, will work to replace the bulb currently in the headlamp now? If I'm able to figure out how to post pics, I will most certainly do so. Thanks in advance.