Carson Magnifier Head Light 16340 battery mod

The original Carson Magnifier Head Light runs on 3xAAA batteries that take too long to charge, so I made this mod that houses a single 16340 / RCR123A  Li-Ion battery instead. Rechargeable li-ion batteries have more capacity and take just one hour to charge.

Required material

• 1x pair of 18650 battery box lead contacts (found on AliExpress)
  • 1 flat (positive)
  • 1 spring (negative)
• small flat screwdriver
• small wire cutters
• file for plastic/metal
• soldering iron, tin and paste
• hot glue (optional)
• one rechargeable 16340 li-ion battery

Instructions

Taking apart the old battery housing

1. Take out the batteries (if any).
2. Using tiny wire cutters, cut the two wires from the battery leads in the housing.
   • Check if the red wire connects to the ‘+’ pole (the flat battery lead), and the black wire connects to the ‘-’ pole (the one with the spring), as sometimes the wires are mounted in reverse.
   • If your wires are reverse (black is ‘+’) it is might be a good idea to open the LED housing and swap the wires by resoldering them so the red wire is ‘+’ and the black one is ‘-’.
3. Using a flat screwdriver as a lever, carefully push out the arm holding the light, from the old housing.
4. Take out the magnets:
   • Pull out the base plate (doesn't matter if you break it) and push out the magnets.
5. Take out the white ribbon for pulling the batteries:
   • Using the screwdriver as a lever push out the rectangular plastic that holds the ribbon in place.
   • The ribbon has a knot on one side - leave the knot.
6. Save the battery cover, as you will reuse it on the new housing.

Printing

Slice on PrusaSlicer, default 0.20mm QUALITY settings with 10% infill, organic supports (on baseplate only) and a brim. I recommend organic supports as they are easier to remove.

Print in ASA, PETG, or PLA.

Installing the new battery housing

1. Clean up the printed part:
   • Carefully remove the supports and the brim. 
   • Be careful not to break the battery contact holders.
   • File down the edge where the brim was connected.
   • Ensure that the battery lid can close and open without obstructions from the remaining excess plastic.
2. Mount the LED light in the housing:
   • Lead the wires through the hole on the housing
   • Push the arm holding the LED light in its place. It should fit snugly.
3. Connecting the wires:
   • Cut the tabs on the new battery leads, leaving just 5mm.
   • Bend the leads at 90° angle.
   • Solder the wire to the battery leads before pushing them in their place in the housing.
4. Push the white battery ribbon through the opening on the bottom:
   • The knot should be tucked in the rectangular hole.
5. Push the battery leads in their places:
   • Positive pole (flat) should be on the side near the ribbon.
6. Fix the excess wires in place:
   • Put the LED in the most upward position to ensure that the wires are long enough.
   • Tuck the wires in the channel on the bottom. Optionally, you can fix them in place with a drop of hot glue.
7. Mount the magnets
   • Clean the holes from the supports and push both magnets in firmly in place.
   • Magnet polarity does not mater.