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 positive spring makes good and consistent contact with the top of the cell, so I didn't have to do something about the Streamlight's ring terminal piece that brings the negative up to the top of their battery for the recharging port. If I keep working on this, that will be the next task.

I made it with a channel to run the wire connecting the washers or if you have a