Convert Ikea LED Candle to Smart Wifi Candle

The Ikea "Godafton" block candle is a battery powered LED candle, with a timer function, 6 hours on 18 hours off.

These look pretty good, but they are known to be voracious battery eaters, 2xAAA. And thanks to the timer circuit, continue to drain the battery until it leaks all over the place.

So instead of throwing away the 6 candles I had, I wired then to a USB power source, to eliminate the battery limitation, and added a wifi controlled switch.

Step 1: Safety First!

Safety first! Put on safety glasses, don't take them off until you're done! I don't want to hear any excuses. The combination of bad chemicals and little springs under pressure practically beg to flick something nasty into your eye.

Step 2: Clean Up the Mess

Corrosion and battery mess everywhere. Take out the batteries and put them in a bag for safe disposal.

Neutralize the corrosion with vinegar. Since the back cover took the brunt of the battery spill, I took it off and soaked it in a yogourt cup filled with picking vinegar. Look at the bubbles! Better living through chemistry!

Clean the terminals with a q-tip. You better be wearing your safety glasses! The damage ranged from bad to not much at all across the six.

Step 3: The Circuit

Two AAA batteries supply a voltage of 3V and according to the back cover, power consumption is 0.06W. Using V=IR and P=I^2R, I solved for a resistance of 417 ohms. The closest I had was 220 ohms.

Wiring up a test circuit, and measuring the voltage was about 2.5V. a little low, but it was working fine, so I can live with it.

Step 4: Wire It Up

I used some speaker wire I had left over for power wire. Soldering is hardly my strongest skill, but I got some practice here, do everything six times!

I also nibbled a corner out of the battery cover for the wires. So the candle doesn't sit funny on the wires, I got some stick on rubber feet.

I took a USB male to male, type A, cable and cut it in half. This made my two power wires, since I was going to set these candles up in a set of 2, with separate power supplies. USB power supplies the juice.

Tiny little wires, what a pain. I'm sure there are better suppliers of USB cables made for splicing into random projects, but my supplier is the Dollar Store.

Step 5: Testing

Remember, diode = One Way, so get it right before you stick it together. You can unstick it if its wrong, but its a pain, so get it right the first time.

Step 6: Done!

Yes! All done! Wires can be a pain, but no more batteries, and no more meltdowns.

Step 7: Make It Smart!

Since these are going to be put in an awkward spot to turn them off and one, I am using wifi smart plugs. I got these at Costco, CE Smart Home brand, and they work well. I'm sure the security experts are rolling their eyes at the gaping holes in my wireless security since I'm using these, but they work well, and they work now. In the future I would like to replace it with an ESP 8266 wifi module relay. But that is another project.

Step 8: Final Things

Some things I would have done differently. I wish I had used smaller wire in white or clear insulation. It would have blended into the background so much easier than "vibrant blue". But blue is what I had.

Using the cheapest USB cables as a power supply was not the easiest to work with. When I replace the USB smart plug with the ESP8266 relay, I will defiantly buy a USB Type-A cable with wire leads, no more “chop off the end and sort out the wires inside”. The wires are so fine, I am a little concerned that the connection won’t last very long before it fatigues and fails.

I checked the final voltage at the terminals, because the candles seem a little dim compared to what I remember. The candle has a circuit built in to make the LED flicker like a candle flame. The voltage is all over the place when I measure it, bouncing from a low of 1V to a high of 3V. I still don't know if the resistor I used was the right size. Unfortunately, the only other sizes I had was 1K ohms, 10K, and 100K.

Overall, I'm happy with the result.

Comments

[ludvik.tesar]

I was also experimenting with similar IKEA LED lights. They are made to flicker like a flame, but in my opinion, they flicker very little. You have to focus for a while to see it. So, I hacked them to flicker more. My version was 1814 Godafton typ M1604 for 3V lithium battery CR 2032. In the end I added resistor 4k7 between plus pole of the battery and pin 5 of the 8-legged chip. It is the only pin that seem to be unused and floating, but it has a suitable place to solder something. Resistor 3k9 make it flicker too much and too regularly, 10k is still not sufficient. 4k7 seems to be right one to make it flicker like a flame.

[nataelj]

Something in the resistance calculation seems off to me. I think there's a resistor already in the candle actually, which you can sort of see in the video ataround five minutes in.

Unfortunately the video isn't clear enough for me to see exactly what resistance it is, but through simple testing I found that a 22 Ohm resistor added to my new circuit seemed to result in approximately the same current as from batteries. That might be more the ballpark to use to keep brightness levels the same, and I'm guessing that means the resistor in there might be around 36 Ohms?

In my case though I also seemed to have about double the amps you did so it's possible I have a different model of candle; for me the amps jumped around between around 16 and 23 mA.

[dchall8]

A couple of ideas came to mind on this. First of all, great idea and implementation. I LOVE this.
What about this idea: instead of hard wiring the candle, install a telephone receiver jack on the candle. Wire that to the candle, then you can use telephone wire for the connections. Connect and disconnect the wires with the clip on the end of the wire. Phone wires are solid copper and there are four in each wire. For the USB connections, you can buy a gang block that takes many phone jacks to collect them all for the USB connector. You could put a USB female on the phone block to take regular USB wires.
And can they be made to flicker?

[Rice_and_beans]

Using telephone wire is a great idea. Hard wiring is so permanent, and I originally wanted to be modular, almost as flexible as batteries. Ill keep this in mind for the next project.

They flicker, but that is all part of an internal circuit by Ikea. They also have a timer which shuts them off after 6 hours.