Converting a 3x AAA Battery LED Light to Li-ion

These LED candles provide a nice level of light and are safe to leave "lit" anywhere at any time unlike normal candles. What I don't like about these however is that they use three AAA batteries in series. With a typical capacity of 1200mAh (for alkaline) these batteries get notably dimmer in a couple of days, and become e-waste in a week.

So with a handful of parts (which costs less than the price of a new pack of AAA batteries) I'll show how easy it can be to make this type of light rechargeable!

Step 1: Disassembly

The wax body of this candle had some cracks from shipping which made pulling the plastic base out quite easy. This was held in with some hot glue, so a drop of IPA would also work to loosen the base.

In the second picture you can see a 6 pin IC with no markings which directly drives the LED via a surface mount resistor. This board also has what I presume is a 3 pin IR receiver, perhaps for different modes of operation? I did not receive a remote with these so I can only guess.

Step 2: Obtaining Parts

I had this TC4056A charger board on hand, as well as the DW01 protection board which is soldered to the 18650. The 18650 cell itself is salvaged from a laptop battery, it measures around 2.4Ah and will be perfect for this low drain application.

Step 3: Wiring

Place the TC4056A charger board in the battery compartment and pass wires into the inside, then solder these wires to the respective battery compartment contacts as shown.

Solder wires onto the Pack+ and Pack- terminals of the protection board, then solder these onto the same contacts as the charger board, noting the polarity. I added some tape to the exposed battery contacts just to be on the safe side too.

Step 4: Reassembly

I used some hot glue to securely mount the 18650 upright on the candle base, then glued the base back into the wax shell. The 18650 is not visible through the wax shell at all which I was pleased about, and now if it goes flat I can simply pop the cover off and charge it rather than put AAA batteries in there.

I hope you enjoyed this quick instructable and if you have any feedback please let me know :)