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I have a pile of lipo batteries that have gone bad and haven’t been able to dispose of them properly. Most have a bad cell or two so they’re dangerous to throw away or destroy. I needed a solution to discharge the lipos completely and found a cool article by Oscar Liang for a do-it-yourself discharger. I followed his spec, except I only made a 12 volt version instead of his version with a jumper to switch from 12 to 24 volts. I have a cool little discharger (3rd image) for bringing batteries to storage voltage so any lipos I have that are over 12 volts I set them to 3s and let the discharger bring them down to the 12 volt range. Then I slap the battery on my discharger and it will kill them quite fast. After a few hours, or even overnight, the voltage on even a 6 cell is only around .01-.04 volts. At that point I can just short the positive and negative wires together and finish it off. Then I clip the plugs off and save them for other uses and the batteries are ready to be disposed of.
Being the geek that I am, I designed and 3D printed a little case to make it nice. Here’s the final product.
And here it is in action. The lights start out quite bright and hot if the battery is up at 12 volts, but after a few seconds they dim as in the photo below.
And below is the discharger which I bought at Pyrodrone for around 6 bucks. It has a little button to switch the values to 2s, 3s, 4s, 5s, 6s. The battery I’m discharging is a 22 volt 6S which I’ve got down to 15.2 volts.
I’m happy to report I passed the FAA Part 107 test for commercial drone pilots, Unmanned Aircraft General – Small (UAG). I scored a 90% but I know I missed a dumb question or two. I can now utilize my incredible drone flying, photography and video skills to make some money safely and legally.
Comments on the FAA 107 Test
Below are the general categories I missed questions in. I missed 6. I kind of remember some of them. I can’t believe I missed something on a METAR but I did.
One question asked if you can fly in prohibited or restricted areas. Everything I saw online said you can’t fly in prohibited (i.e. Camp David). I believe you can fly in restricted. But it said the restricted needed permission from the org that operates the restricted area, not ATC. It was a confusing question. Maybe you can fly over prohibited with permission. I’ll have to look that up.
The prior authorization required question may have been just a mistake on overlapping airspace on the sectional charts. I do remember one that I had to look at for a bit. The scenario was inspecting railroad tracks that started in G airspace and went through I believe E airspace, and back to G. I said yes on needing ATC permission, but perhaps that was wrong.
The balance, stability, gravity question was on that asked about the turbulence behind a climbing airplane and what angle or length that turbulence is. (I guess I won’t be trying to fly in the turbulence of an airplane anytime soon).
The balance/stability question may have been regarding the stall speed of an airplane which is overloaded.
“Performance data to calculate the effect on the aircraft’s performance”…. I don’t remember. If it comes back to me I’ll edit this.
Final Thoughts
I’m satisfied with a 90% but mad I didn’t get closer to a 95% because I know a question or two were probably just dumb on my part.
That said, I’m happy to now be able to take some commercial drone piloting gigs here in Utah, for money!
There are many different categories and styles I can cover with my various flying skills and 25 different drones. I can do anything from real estate to sports action. Below is a short list for SEO and reader purposes:
Related: Utah Drone Services
I just finished building a GepRC GEP-CX3 Pro recently. I haven’t built a 3″ for awhile and was itching to add another fun but small ripper to the fleet. This one I decided to put in a Caddx Vista Nebula as I have no desire to add anything analog to the fleet except for larger long range FPV quads.
The frame is an H style, so there are no props in the view of the camera. The rounded front and back make the body look like a Hebrew National, so I’ve named this on “The Hebrew National Quad.”
There was not much space for both 20×20 stacks to fit. One stack was the Vista Air Unit and the other a Mamba F405 mini stack. Wiring sticking out from either stack meant issues, but I did fit it in.
Parts List
The build went fine and the maiden flight was successful. The only issue I’ve had is the motors are hot and the battery life is not as high as I’d like. I’ve been in Betaflight messing with the gains and may have to also adjust the flight controller dampening.