Solar-Powered Interior Mailbox Light

My wife recently ran over one of our cheap solar lights and demolished it. The electronics were still intact and operable, so I decided to tackle a little project I conjured up a couple of weeks ago.

This project re-uses the electronics from a battery-powered, solar-charged outdoor light and adapts them for installation in a standard US mailbox.

I checked the USPS Mailbox Guidelines before I started and didn't see any regulations against this type of project. Here we go!

Step 1: Gather Some Items

This won't be an exact instruction set - just some things to help you think about what you'll need to complete this type of thing.

• A working electronics set from a solar outdoor light, including the rechargeable battery
• A project box to house the electronics and battery
• A mailbox that you don't mind drilling into
• Common shop tools and materials:
  • drill & bits
  • soldering iron & solder
  • electrical tape
  • adhesive or mounting tape
  • caulk or silicone sealant
  • hot glue & gun

Step 2: Remove the Electronics

Carefully extract the electronics and solar panel from the assembly. If you can't keep everything intact, ensure you have documented the wiring connections you severed. Electrically-speaking, this system will be re-connected exactly as it was originally. Only this time inside a mailbox.

Step 3: Disconnect the Solar Panel

My intention was to mount the solar panel on the top of the mailbox and have everything else inside. I disconnected the wires from the panel so I could run the connections through a small hole in the top of the mailbox.

Step 4: Install the Electronics in a Project Box

I went looking for a project box in the shop and came across a surface-mount telecom box that happened to be the perfect size for what I was doing. The AA battery fit across perfectly!

Find a way to mount the battery connections to hold the battery in place and drill a hole in the box to place the light in. Arrange the wires as necessary and glue things in place wherever you see fit.

When everything is in order, you might want to test the kit to ensure it's all working (except the solar panel, obviously). When you are satisfied, everything is in place, and the cover is on, it's time to mount everything on the mailbox.

Step 5: Prepare the Mailbox

I picked a spot toward the back of the mailbox to mount the light and drilled a hole to pass the photoresistor and the wires for the solar panel through. The photoresistor at its widest point was 9/32", so that's the size of the hole I drilled in the top of the mailbox.

Step 6: Run the Wires and Reattach the Solar Panel

Pass the photoresistor and the two solar panel wires through the hole and re-solder the connections. I chose to hot-glue the photoresistor back to the window in the center of the panel since that was part of the original design. I didn't see a need to deviate from that - this was a perfect setup in my opinion!

Step 7: Make a Mess With Sealant

At this point if everything still works (please test operation at each step!) you should be ready to mount the solar panel to the top with a silicone-type sealant. I happened to have a tube of silicone-based, clear-when-dry door and window sealant so I just smothered it on all over. I'm a function-over-form sort of guy so as long as it works it's fine with me.

Step 8: Mount the Light Inside the Mailbox

Almost finished. All that's left is to stick your new light box to the ceiling of the mailbox. I used hot glue because I couldn't find any mounting tape.

Reaching in a mailbox with both hands and a hot glue gun is not a good idea. I would recommend mounting the light box with some double-sided foam tape or automotive trim mounting tape.

Step 9: Test the Light and Install the Mailbox

All done!

If everything still works, install the mailbox and enjoy!

This is my first published Instructable and I hope I've been clear enough about the process - let me know if I skipped anything major!