Hey all! New here, but have been a flashlight geek for years and finally decided to mod my first light.
It’s a generic quad-LED 12v pod light that uses 5054 LEDs.
My issue is that I can’t figure out how to determine the voltage of the LEDs so I can’t figure out what I should replace them with. I’ve attached pictures of the board, and I have no idea how to figure out what I could consider replacing these with. I have tried using all of my google-fu to identify the components to see what components may dictate the voltage, but all I can find is that the 470uh inductor may lower the voltage. Can anyone maybe bail me out and help me figure out what the end voltage may be with this? Or is that not possible without seeing if the LEDs are in series or parallel?
Hey, if you have a multimeter you could try to measure the forward voltage on each led’s from the side of it while it’s on.
As I see there is some of exposed pads on the sides of the led, try sticking the multimeter probe there to measure the voltage
This feels like one of those situations where I lost the forest through the trees lol. I’ll give that a shot and see how it goes.
Wouldn’t measuring the voltage at the red/black wires when the light is on tell you what volts the driver is putting out?
I see a little mark near the LED pads (next to the “L” In LED1/2/3/4). So it looks like they’re all oriented the same way, picture-wise, in terms of polarity.
Hard to tell from the pic, but I believe I see a trace from the top (pic-orientation) of LED3 to the top of LED 4. Assuming that’s the same polarity, I would think these are in parallel.
You could try posting a few more pics from different angles to help us see the underlying traces. Try to find where the traces begin and end and how they connect between the LED pads.
It only allowed one picture when I posted since I’m a new member, but here is the other one. It’s much clearer on the lines. It also looks like the LEDs are split into two pairs in the circuit.
I also finally ordered a bench power supply for me to play with my assorted 12v toys. It’ll beat lugging a car battery into my workshop every time I get an itch lol. Should be here tomorrow, and I can check out the voltage then.
Those are just inputs, it’ll be 12v there.
Much better pic, thanks. Going off the pic orientation, it looks to me like the top of all four LEDs are connected to the top of the inductor. I believe all four are in parallel. Does that look correct?
Do this at your own risk, but if it were me I’d check voltage with a neg lead on the top pad of L1, and the pos lead on the left side of D4.
Thank you! I have almost no idea of what I’m looking at, and your input is super helpful. If I can bother you for some more info, what are the risks of checking the voltage between the diode and the led? And what would the significance of that value be in contrast to just checking voltage across one emitter?
I’m seeing spots because I just checked LED voltage on one of my cheap lights while it was on. I’ve actually never done that.
AFAIK either should be fine as long as you’re careful with the meter probes. I’m 90% sure those are in parralel so you’d see the same voltage with either position. If they’re in series, you might see say 3V at one LED, but 12V between all four (testing between the top of the inductor and the left side of the D4 pad).
If you’re uncomfortable with doing the test, or this is an expensive light, etc. maybe someone else can give confirmation or a second opinion on how to test.
From the picture I can see that the LEDs are wired in parallel, and you can get their voltage by probing both sides of any one LED, or also probably by probing the solder blobs to the left of the label “D4,” but the light will need to be on in either case. You could solder a wire to either blob so that you can probe remotely without blinding yourself. “Sensepeek SP10” probes are quite handy for this sort of thing, or some DIY equivalent such as solid core wire with pogo pins soldered on, or even just bare solid core wires. Be careful not to short anything.
Thank you guys for the input! I’m waiting on my PSU to come in so I can do it in a little more controlled environment than just hanging some wires off a battery. It got delayed but supposedly will be here tomorrow. It’s a $10 light off ali so I’m not too worried about frying it, I got it to learn and worst case I’m out $10.
Okay, just checked the LEDs, and they are coming out at 9.4v across the emitter. So it seems I may have a fun time finding a viable swap option
They are probably just 12V LEDs and you’re seeing the effects of a voltage drop due to them being on.
Did you get your power supply? Perhaps ee if you can light one up with 12V.
I did, I have no idea why I waited this long. This thing is fun. And pushing 12-14.5v through it results in 9.4-9.6v so I’m thinking it could be drop across the LED. I just double checked the specs on the light and it’s meant to handle 9-36v, so I tried it at 25v and still found 9.5v across the emitter.
Awesome. This is fun figuring this stuff out together. So perhaps the next step is popping one of those LEDs off the board so you can see the exact footprint. Once that’s done you can double-check the LED will light up with 12V from your power supply (you could do the same test in place though).
It really is. Thank you again for all the insight. I’m gonna test on the board as I don’t have a hot air iron(yet) and am getting tempted to just mount these up and run them as they are while waiting for a new pair to arrive lol