If I read this correctly, the Nickle Metal Hydrid batteries your trying to use will acquire a memory -- that is if they are only partially charged, then in the future they may only partially charge. These batteries were our worst pain in digital cameras and to fix this I would recommend you use Alkaline batteries. We gave up on NI-MH penlights a long time ago because of this. For one, if your battery dies they are easily replaced and even if your out you can buy a new set at a local mini-mart you'll be ready to go, where as you may not be near a power source to recharge the others. The other bad thing about them is they won't hold a charge, usually only having a shelf life (that is to hold a charge) of 30 days or less. The newer lithium batteries that everyone is going to can hold a full charge for at least a year, and take many more charges than the NI-MH batteries will. You can always carry a few extra AA Alkaline batteries with you.
Hope this helps,
Don....