Streamlight Stinger XT 18650 Adapter

I found an old police Streamlight Stinger XT at the thrift store for $3. It had the old 3-cell sub-c Ni-Cd battery pack but no charger. Battery is NFG. Bulb looked good, so I took it home.

The original battery pack is 3.6V, so I figured an 18650 cell would work fine and modernize the light. I made this adapter to hold 1 cell. Works fine for an incandescent light.

The adapter uses a couple of washers soldered to some 18ga speaker wire to make the connection to the base. To my surprise, the