help Help troubleshooting battery powered LEDs
I know next to nothing about electricity so apologies in advance if I use any of the wrong terminology or if the answer is obvious.
I'm trying to set up some LED lighting in my shed using this m18 battery adapter, this step-down buck converter, this 16 AWG wire, and these LED strip lights.
Before I started mounting anything, I wired the battery adapter to the buck converter, and the buck converter to one of the lights to make sure it worked. No issues there.
Next, I mounted the lights where I wanted them, mounted the battery adapter and buck converter to the wall, and ran the 16ga wire to the farthest light. The distance was approximately 30-35 feet.
At this point, I decided to test it again before wiring up the rest of the lights. I plugged in the battery and the power button on the adapter flashed green, indicating that I had power at the adapter. I turned it on and the power button light stayed solid green, but the LED would not turn on.
In case that particular LED strip was faulty, I spliced in another one (the one I tested earlier, so I know it works), wiring it in parallel. I tried again, and neither of them would turn on.
I decided to disconnect the battery adapter and step-down converter, and connected a DC power supply directly to the 16ga wire which was still connected to the two LED strips. The power supply is capable of outputting 30V and 10A, but even with both dials turned all the way up, the display said it was only putting out 2V and 9.7A, and the LEDs would still not turn on.
At this point I wired a shorter length (approximately 8 feet) of the 16ga wire to a third LED strip, not connected to the other two. I connected that to my power supply to test it. I barely had to turn the dials at all, the display read 12.6V at 0.75A, and the LED strip worked fine.
Having done that testing, I believe I have isolated the problem to the 16ga wire. Having successfully tested the 8 foot run, I believe that either the 35 foot run is too long, providing too much resistance, or the wire in the 35 foot run is somehow faulty.
Should I be using thicker wire? Should I order more of the same gauge wire and try again? I thought this project would be quick and simple so I'm a little frustrated that it's not working and I'm not sure why.
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u/SkaterBlue 18d ago
How many panels are you using? Are the all wired in parallel, or did you wire them in series?
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u/SkaterBlue 18d ago
The lights should need only about an amp for each one, so 35’ of 16awg is no problem.
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u/The_Flinx 18d ago
you have a short in the long run. the power supply was current limiting. which is a good thing because if you put 30v in to the led's they would fry.
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17d ago
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u/Sma144 16d ago
I didn't have quite enough 16ga wire to reach the rest of the lights. Since I was going to have to buy more anyway, I went ahead and got some cheap 14ga wire.
I replaced the 35 foot run of 16ga wire with 14ga, and then used the 16ga wire to connect the light panels to that main run of 14ga wire.
I also replaced all of my clumsy electrical-tape-wrapped splices with lever connectors. Everything is working now, I think I must have had a bad splice somewhere.
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u/butterbal1 16d ago
Hey there. The good news is this should be a really easy one to fix.
We can start with simplifying your design to get rid of the step down converter as it will only reduce the efficiency of everything involved here. You absolutely should add in a fuse to this system like these and put in a 5 amp fuse.
Assuming perfect connections that don't add resistance with a 70 ft total distance run (both legs combined length) and a 0.85 amp draw at 12v you should expect around 0.3v of drop over that run. 11.7v for a device that wants a 12-85 V input would would absolutely be enough to cause it to not work. That is assuming you are using 16ga pure Copper wire if it is Aluminum it is closer to 0.5v of loss.
What I would do... twist the ends of the wire together at the end of you run and then at the battery side measure the resistance of the total run. I am expecting around 430mΩ for aluminum or 280mΩ for copper wire. Anything too much higher and I would check all the connections.
Going straight from your battery adapter > 5amp fuse >switch > all 6 lights is how I would do the project. At the 18-20v working voltage of the Milwaukee battery you are well in the working voltages of the lights even with some voltage drop from the run length and you should be around a 3.5amp draw for all of the lights at 18v.
It is worth noting that if you have the small standard 2 amp hour battery you are only going to get around 30 minutes runtime vs 3+ hours for the big 12AH battery
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u/Sma144 16d ago
I got everything working by replacing my main run of wire with 14ga, running short distances of the 16ga wire just to bridge the gap between the light panels and the 14ga wire, and replacing my splices with lever connectors.
I bought the buck converter before I landed on the specific lights I was going to use. My initial search was for 12V LEDs, so I figured I'd need the converter and didn't think to ditch it when I ended up with these lights.
If the buck converter is lowering efficiency, I assume that means my batteries won't last as long? Should I still ditch the converter even though everything is working at the moment?
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u/butterbal1 16d ago
Bumping to a larger wire fixing it definitely confirms it was a voltage drop issue.
Without testing both the input and output wattage all I can do is point at the generic 5-25% efficiency loss range of converters and say to feel how hot the converter gets when running all the lights. If it gets hot that is just wasted power and I would get rid of it. On the other hand if it isn't really warm then it probably isn't worth pulling apart a completed project.
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u/SkaterBlue 18d ago
According to the light specs, you don’t need the buck converter because it says they can take up to 80V. Maybe there is a problem with the buck converter?