My kids love to read in bed, we have bought bags of these one dollar headlamps over the years, until I started converting them to rechargeable. After converting these to a rechargeable battery they can be charged using a simple cell phone charger.
My kids love these. The conversion only takes about twenty minutes to do.
One thing that I want to make clear is that this does not just apply to a certain headlamp purchased from walmart. This is meant to be a guide to adding a rechargeable battery to any 3v electronic item. If you have something that takes two double A batteries, then the chances are that this process would work to make that electronic item rechargeable. I have used this process to convert many toys, remotes, flashlights and many other things.
It is a bad idea to completely drain a lipo battery.
Step 1: Parts / Materials
Here are the parts that I used to build this Headlamp
- el cheapo headlamp -- Walmart - $1
- Micro USB 1A Charge Board -- Amazon - $1.30
- 380 mah Battery -- salvaged from rechargeable Bluetooth keyboard. See more about salvaging batteries in the next step.
- Heat Shrink tubing -- I have used this heat shrink kit for a while, it works great and has a good variety of sizes.
- Big heat shrink Tubing - I also use a 1 1/4 in heat shrink for this project. It can be found here
- Soldering Iron -- If you do not have a soldering iron This one is an inexpensive good one with variable temp.
- Hot Glue Gun -- Dewalt (obviously)
Step 2: Salvaging a Battery
I am salvaging my battery for this project from a bluetooth keyboard. I received about 150 of these keyboards from a computer recycler. I contacted an electronics recycle company many years ago and have worked with them for many years. Lots of parts and electronics do not hold any value to a recycler who basically wants these for the precious metals. There is not a lot that can be recycled out of a plastic bluetooth keyboard. A lot of times they (the recycle guys) are more that willing to let you have the stuff that they can not recycle. The key thing is to be polite and respectful, remember that this is what they do for a living. Offering a few dollars or a case of beer is a good way to get lots of parts that may not be valuable to them, but would be very valuable to you.
Another great source of parts is just unused electronics and toys. I have salvaged batteries from radio control cars, helicopters, other toys, etc. Anything with a battery, fan, motors, even wires and connections should be salvaged before it hits the trash.
The best recycling is reuse.
Back to my project. I took apart the bluetooth keyboard and unsoldered the 380mah battery.
Step 3: Take Apart the Headlamp and Prepare the Case
The first step is to take apart the case of the headlamp. This one was easy as it only had one screw. One thing to make sure is to mark the positive and negative on the board so that you make sure to hook it up to the battery correctly.
I also used the dremel tool to modify the case so that the battery would better fit behind the light.
Step 4: Hook It All Up
The hook up for this is easy. The battery leads needed to be extended, and connected to the charge board. Easey peasy, the red goes to positive or "+", and the black goes to negative or "-". another lead goes from the charge board to the light. Easy as that.
I then put a peice of large heat shrink over both the battery and the charge board to hold everything in place. Before I shrunk the heat shrink, I measured and cut a hole in the heat shrink so that I would be able to see the red and green charge light once the heat shrink is "shrunk".
Next I shrunk the heat shrink down so that everything is held into place. Then I ran the remaining leads to the LED light board. After that I put the covers back into place and assembled the headlamp. I Hot glued the battery / charge board assembly to the led light assembly.
Step 5: All Done
The headlamp is all done. It has been retrofitted with a rechargeable lipo battery. It runs longer, and will save money in the long run.
Thanks for reading.