Something weird is going on. Devices don't care what kind of battery is powering them, as long as they have the required voltage and the battery can deliver the required current. (Not hard to do with these lights.)

Try putting some tin/aluminum foil on one end, just as a test, to make the battery longer. (If you still care that is.)

Alternatively, if you have any other way to charge the battery (another light perhaps?) then charge it first, THEN put it into your nightrider. See what happens then!

If you have an electronic savvy friend, take the battery and light to them, I'm sure it's an easy fix.