This short Instructable shows you how to convert a flickering flame light bulb into a battery powered offgrid device.
This conversion works with most flickering LED light bulbs on the market, but maybe not with all. I can you not give you a guarantee for that! You might brake the light bulb and void the waranty! But on the other hand you can get them for less than 10$ in a special offer.
Advice: If you want to go for a long battery lifetime go for the ones with 3W output. They might not be as bright but consume lower power!
This is a 3W Light-Bulp.
This is a 4-7W bulp.
Step 1: Disassemble the Bulb
I usually test the light bulb before I start the conversion. If it is already broken, send it back and get a replacement!
Before you start the disassembling make sure to unscrew the light bulb from the socket and disconnect it from the power!
The milky opaque upper cover can in the most cases just be unscrewed from the base. Sometimes it is glued and needs some breaking forces. Make sure not to break the cover or you will have to go and look for a replacement! :-)
Then you already see the LEDs and the drivers on the cylinder on the inside.
The lower metal E27-socket part can be removed with a strong plier. As you can see in the fourth picture, one wire goes to the lowest part of the socket and the other wire was just clamped between the outer part and the plastic housing. A potential thread for a deadly electric shock if the lamp is screwed into the socket.
Step 2: Remove the Existing Power Adapter
In the cylinder itself is the mains power supply unit.
These are very simple ones and create a lot of EMC noise and if the fail, the may cause a fire, because they usually operate at the upper level of what they could supply!
Cut the wires and through it away!
Step 3: Check the Power Supply and Current
Now it is time to have a look at the connectors for the power wires on the cylinder.
Best if you can find some marks of "+" and "-". Then it is obvious.
If that is not the case, mostly positive end uses red wires while negative end uses white or blue wires. But that must not always be the case.
If you are not sure there are several ways to check:
- Connect the cheap power supply to 220V and measure which cable is which polarity. This is very dangerous because you are handling with 220V AC without any safety measures. I would not advise you to do so!
- Much better: Look at the cheap power supply and look how the output is labeled. In best case there is the polarity noted. If not, there might be a polarized capacitor close to the output. This can be used to see which output is plus and which is minus.
- The easy way: Look at the PCB of the light bulb that is there on the cylinder. you might find some connections from the power supply to the IC part. Then you only have to check the datasheet to see which is which.
- the experimental way: apply a small voltage with limited current (<50mA) and see if there is a reaction. This way you risk to damage the device completely. At the latest when you see the magic smoke leaving the device you know that this light bulb is gone.
If you already know the polarity, you can test in the next step how much current the light bulb wants and if it also works with a plain Li-Ion battery (3.7V).
Step 4: Add USB Power Supply
This is the easiest way to power your bulp, because with the USB cable you can use any USB power supply to drive this device.
This might be a power bank or a wall wart USB-charger.
I would always use this approach if the bulp will be installed inside a lantern or mounted on the wall. Because you will eventually never have to touch the device again. Only plug and unplug the USB-cable to switch it on or off.
You can use an old USB cable or buy a new one specifically for this purpose.
If you use an old one, make sure the polarity is correct! Because red and white are used for the D+ and D- of USB, the power lines mostly have other colors. But you can very easily and without any danger measure that with a multimeter!
Step 5: Add Li-Ion Battery Holder
I chose to hide a 18650-size Li-Ion cell inside the LED cylinder. I have a lot of these cells harvested from old laptop batteries.
I already checked that the device could be operated with 3.7V and it worked. The current while flickering was about 230mA, the "all-LEDs-On" was about 300mA.
This is a very powerful bulp, because with 5V it drew almost 0.9A. Which is certainly too much for most USB-Ports! Although newer power banks should be able to deliver that amout of current.
Just solder the battery mount to the power connector and as soon as you insert a battery the bulp will light up.
Because that is a little bit inconvenient, I added a small switch to the bottom of the bulp.
Step 6: Add Switch
The switch is mounted to the side so the light bulp can stand on its own on a flat surface.
I just drilled a hole in the side of the lower mount and glued the switch in.
Make sure you add sufficiently long enough cables to the switch and the battery so you can change the battery without removing the switch!
Step 7: Mount the Remaining Light Bulb
Optionally you can mount the rest of the light bulp to a wooden board or a cardboard.
Of install it into a lantern.
And then enjoy your off-grid mobile fire!
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