Super Simple Battery Powered Flame Light

During many hours of COVID-19 YouTube bingeing I became inspired by an episode of Adam Savage's One Day Builds, specifically the one where he builds a gas lantern prop for his homebuilt rickshaw. At the heart of the build was the conversion of an off-the-shelf, AC-powered flame effect lamp to battery power. I wanted to replicate but also improve on his design, specifically implementing a more compact, self-contained design. Plus, my wife and I had some decorative votive lanterns that would make a great way to display the lamp.

This instructable is divided into two parts. The first details the AC to DC lamp conversion, and is more or less just a restating of what you can view on Adam's YouTube channel. The second explains how I modified the decorating lantern and installed my lamp unit.

NOTE: I assume you have basic knowledge and experience in simple electric circuit assembly.

DISCLAIMER: This build involves modifying a 110V AC device. Ensure the flame bulb is disconnected from the socket and do not attempt to reuse the AC-DC converter in the base of the lamp. Also, the particular LED circuit referenced below operates on 3V DC. Other models may vary so, as with any electrical/electronics project take care when working with these devices.

Supplies

To create your own DC flame lamp you'll need:

LED flame effect lamp bulb (Amazon)
AAA battery holder (Amazon)
Micro switch (see instructions)
Copper wire
2 AAA batteries
Hot glue gun and glue
Soldering iron (ideally) or other method for connecting wires

If you want to replicate the decorative lantern you'll need:

Lantern (available on Amazon, eBay, craft stores, etc.)
Acrylic sheet (.080 thickness)
Clear matte spray paint
Black matte spray paint
Double-sided foam tape
Acrylic cutting (or utility) blade

Step 1: Disassemble Flame Lamp

The first step is to disassemble the flame lamp. The model I bought (and listed above) consists of a screw base, blue plastic plate, and plastic diffuser that disconnect simply by pulling them straight apart. (I first thought they might require a twisting motion and ended up snapping two of the solder connections, which was fine since I was going to solder new connections anyway.) The blue plate has slots into which tabs on the diffuser fit.

After separating the parts you'll see an AC-DC converter housed in the lamp base and a flexible PCB containing over 100 LEDs mounted to a rigid green PCB underneath the diffuser. (If you peak inside the flexible LED "cone" you will see the microcontroller that drives the flame effect.)

The final disassembly step is to detach the LED assembly from the AC-DC converter. You can either simply cut the wires or heat the connections with a soldering iron and remove them that way. Once the LED assembly has been detached pull the wires through the blue plastic plate and set it aside.

Step 2: Attach Battery Holder

Once you have the blue plastic plate separated from the rest of the lamp the next step is to mount the battery holder. For my build I did not have a AAA holder handy so I cut down a AA holder. Depending on the dimensions of your battery holder you may need to trim/sand the corners to get it to fit inside the blue plastic plate (I did).

Attach the battery holder to the blue plate (it doesn't matter which side) with hot blue and thread the wire leads through one of the holes to the other side.

NOTE: In the end my cut-down AA solution was not very robust and so I have ordered some AAA holders and will retrofit one when they arrive.

Step 3: Wire Switch and LED Assembly and Test

Now it's time to complete the circuit. How you do this will depend on the switch hardware you have. I happened to have some DPST microswitches in my shop with posts that conveniently fit through the slots in the blue lamp base. You may need to drill some holes or modify the base. (I did need to drill a hole to allow the wires to fit.)

If you look at the photos you'll see that I threaded wires through the base, soldered them to the switch posts and then covered them in shrink tubing. Whatever method you chose (solder, splice/tape, etc.) you just need to form a simple circuit with:

LED assembly (+) to battery lead (+)
LED assembly (-) to switch
Switch to battery lead (-)

Once you've completed the wiring, insert 2 AAA batteries into the holder and test the connections. You should see the LEDs flicker. If so, press the diffuser back onto the blue base. If not, re-check the connections.

At this point you have a compact, self-contained, battery-powered flame lamp to use in whatever application you wish. If you want to see how I mounted it in a decorative lantern just keep reading...

Step 4: Create and Paint the Lamp Base

The lanterns we had on hand featured a circular base designed to fit a glass votive holder. I started by making a template out of foam core that fit snugly in the lantern base. I then transferred that pattern to a piece of scrap poplar I had on hand. Next I traced an outline of the blue plastic base, trying to center it as much as practical inside the outer diameter. (I didn't need it to be perfect since it was going to be hidden inside the lantern.)

I used a drill and coping saw to cut out the inner circle that would hold the blue plastic base and sanded it until the base fit snugly. Likewise I cut out and sanded the outer diameter until I had a wooden ring that held the LED assembly. Lastly, I masked off the diffuser and painted both the wooden ring and blue plastic base matte black.

Step 5: Create Frosted and Smoked "Glass" Panels

In order to disguise the lamp bulb inside the lantern I cut four panels from .080 acrylic using a straight edge and utility knife based on the internal lantern dimensions. (Score the acrylic 5-6 times and then snap the pieces on the edge of your work table.) I painted them completely with clear matte spray paint and then applied an over-spray of black matte on one edge to simulate a "smoke" effect. I attached them to the inside of the lantern (painted side facing inward) with double-stick tape.

(NOTE: Our lanterns featured a hinged door with a locking mechanism that required one piece of acrylic to be slightly narrower to it would allow the door to close completely.)