Was bored and planning to connect some SFH55’s together but for the life of me I cannot find a suitable driver. I know convoy has a 50a driver but the voltage is low so I’d have to buy many of them. Are there any known beefy drivers that can handle the load? Saw one on amazon/ebay but was reviewed with inconsistent current regulation.
You’re hoping to run 12 of these in series? and these things are 11mm x 11mm?
Is this for a flashlight? This sounds like it could be a stadium light.
I’m sorry I don’t know much about available drivers but would it be beneficial or easier to find a driver is you went to do a 2S6P Setup at 6V?
I mean I wouldn’t necessarily say its a conventional flashlight but it’s gonna be a hand held light definitely. Just might be a tad heavy.
Welcome to the forum @quixful
Sounds like you’re intending to use a tool pack for battery…?
Maybe you “could” get a dc/dc step down with variable output but that won’t address any thermal issues should they arise
I’d be running it using some batteries in series and then preferably stepping it down to correct voltage. I have thermals under control and would be using 10AWG wire so that’s all good. Just the actual converter/driver that I need to find.
+1 on a high outout dc stepdown converter. You can pick them up somewhat cheap from Aliexpress, BUT most all the higher output run off AC power and step down to DC (grow lights, aquarium lights, etc).
The ones that are DC DC appear to all be the same model which I couldn’t really find any reviews on about efficiency or consistency unfortunately. Rather not dump ~$60 onto a converter for it to not even have a constant high current output
There’s the “400w” and “300w” buck drivers on AE. Run a bunch of those to independent strings of LEDs, and control them all with a single pot. These claim to put out 15 Amps.
One of the more powerful drivers out there is the 1800w boost converter on Aliexpress et. al., although it isn’t small. Hook a pot up to the voltage adjustment, for full dimming down to a super low level. To get the most power out of it, Ideally it would be powered at the highest possible voltage with a 14s pack, and your LED string should consist of 24 or more LEDs. This configuration would allow for 1kW output, if the LVP were set to 3.0V.
You could also consider the SFH43 LED, for better optical control in smaller optics, and higher surface brightness at lower current. Or consider 6V or 12V LEDs, to get more power from less available current.
Alternatively you could run them in direct drive, matching the cell count to the LED count, e.g. 4s lipo to 4s LEDs, adding more LEDs in parallel if needed, like 4s2p and so on. SFH55 is super low voltage, so you could even DD them with lifepo4 cells. Switch a mosfet or solid state relay with a PWM signal generator and you’ll gain dimming. Larger SSRs are often only rated for 1kHz, from what I have seen, but that’s an ok dimming frequency.
I thought about running them in direct drive however I was planning to put 12 of them in series since parallel would have absurd current requirements. 12s lipos are too high priced so I might have to run lower cell lipos in series and deal with the restricted Ah. The main issue I was concerned about when running directly is that wouldn’t the lipos near maximum charge be exceeding the rated 3v voltage? I’m not too sure how well the sfh55s can handle an overvoltage
Also for using a pwm what would be the easiest way to go about powering it? Just using a separate battery completely? I couldn’t find one that has a ~36v input so I think that would be the only option other than running it parallel with a step down converter. Makes things more complicated though
For direct drive, also look into “DC Motor Speed Controllers” which are basically a PWM generator and SSRs in the same package. As long as the controller is rated for the amps your LEDs will pull, and the LEDs can handle direct drive, this would be a pretty simple way to power a high wattage array.
Here’s a test of a 55V 60A rated one. Needs strong active cooling at higher loads apparently.
Those look like they would work. Thanks a lot
I’ve looked at a bunch of controllers rated for 60a 55v and every single one I’ve found just had absolutely horrible reviews mostly saying it fries itself past ~30a and higher voltage. Do you know of any reputable models? I think they are over estimating the rated current and voltage for the ones I’ve seen
They need active cooling beyond a certain power level. I think the “DC 10-50V 100A 3000W” ones that include a fan look ok.
The first one I see that has a fan has a guy saying it overheated at only 30 amps with 3 fans (2 extra with the original). Kind of lost as to the best solution for powering these without going the individual resistor route because those i can at least directly cool. MOSFETS on the boards make it difficult to provide adequate cooling .
It is clear that you should perform your own bench testing and improvise on the thermal solution as needed to keep temps acceptable.
Convoy has a 50A driver? Store link?
Might try removing all the heatsinks and make one that I can watercool. As for the driver on their store they have 40mm driver for 3V LED, 28A 54A FET which would work for direct drive but I’d have to get a bunch of them
Well, you could probably put together a 4s DD fet driver like the TA46-Multicell and use an externally mounted high current mosfet or bank of smaller mosfets in parallel to handle the high current.
I don’t know what you’re trying to achieve. If the design is arbitrarily based around the SFH55, you could consider instead to design around a goal, in which case the SFH55 might not be the ideal LED by which to achieve the goal. There are plenty of LEDs that could be more readily powered by a few dc-dc regulators operated by a single multi-gang pot. (I’m not sure if a non multi-gang pot can be used to control multiple drivers, but I know that a multi-gang pot will definitely work.) Smaller LEDs can achieve a decent beam in smaller optics, so you end up with higher power density within a given volume. For instance, you could be running round die L90 LEDs in ~32mm optics or whatever size, powering them with one or more 1800w boost regs, or a bunch of 400w, 500w, 600w, etc. buck drivers. The buck setup is good if you want to avoid higher output voltages. Whether buck or boost, the type of dc-dc reg to use are the ones that have both CC and CV adjustment pots on board. You set the current limit via the onboard CC pot, and wire in an external pot to control the voltage ADJ. This gives you full dimming all the way down to 0% output, and current limit at the top end if needed. Some of these buck drivers have a circuit for low voltage shutdown, but it’s often not documented, and you have to swap a resistor or otherwise maybe add a trim pot to adjust the cutoff.
I did some more searching:
SZ-8025CCCv: 600w buck driver. Claims 25A max out.
AP-D5830A: 800w buck driver, claims 30A max out. Two of these might do the job, and they would fit well with a 140mm fan. I tested the SFH55 LED to require 3.1V at 30A, which is 93W, x 8 is 744W, with a string voltage of 24.8V. If you power this with a 12s pack, keep the voltage above 37.2V (3.1V per cell) to keep the input current to the driver below 20A, in theory. There is a 20A input fuse.
There are substantially more capable boost drivers:
AP-D5060B: 1500w boost, 60V in max, 70V out max, 30A out max.
AP-D100A2000W: 2000w boost, 60V in max, 80V out max, 50A out max.
I might just go direct drive without a controller honestly. Practicality isn’t the point of this build just for fun so I don’t think it’s worth spending ~$100 for dimming. I’ll probably end up getting a spot welder and making a 21700 pack for like 10/15Ah. Should allow for a decent runtime before the output decreases noticeably. Saves money on batteries aswell