Can I use a boost buck voltage converter with a COB LED to control current?

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MarkJohnston

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I want to make a HEAD light with some scrap LION batteries I have around. It's my back up light in case my main light breaks or I get a flat at 2am and need to fix it. (dark country roads out here) Anyhow, I've been doing a ton of research and IM STUCK. I have been looking at 100 Watt COB LEDs and want to make a 12v LIion battery (3s,2p) THe only issue is I hear these COBs will burn out without regulating the CURRENT. But in order to power these LEDs I need a boost buck up converter, or so it seems because the spec charts say I need at least 32 volts for most. I am wondering that will be enough to not burn out the COB. OR would I need a voltage regulator like this as well? OR maybe I'd only need the voltage regulater? Or perhaps I should just make a 8s batter in series with a cheapo BMS? The simpler this is, the better. IT;s going to take a good beating and knocking around packed in my saddle bags.:LOL:

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ALso here is my inspiration for this idea. BUt I am assuming this guys already burned out


:twisted:
 
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It will work with only a buck-booster voltage regulator. But to set the voltage properly you'll need to let your head light warm up. As LEDs warm up they will flow more current at a given voltage.
 
A voltage regulator is not a LED current regulator. So, on the surface, no, it will not work. The voltage regulator will keep pumping more and more current (to keep the voltage the same) as your LEDs burn out. By the sounds of it, you need a constant current, constant voltage boost regulator. This would increase your battery voltage and regulate voltage as well as current. (example below - this may or may not work for your specific application)

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Though as you say, the other option is just to make a higher voltage battery and use only a current regulator. That would be more simple and efficient.
 
4πr^2 said:
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DC-DC 8.5-48V To 10-50V 10A 250W Continuous Adjustable High Power Boost Power Module Constant Voltage Constant Current Non-Isolation Step Up Board For Vehicle Laptop Power LED Driver

Only US$3.40. Get the DC-DC 8.5-48V to 10-50V 10A 250W Continuous Adjustable High Power Boost Power Module for your vehicle, laptop power, or LED driver. This non-isolation step-up board ensures constant voltage and current for efficient performance.
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Though as you say, the other option is just to make a higher voltage battery and use only a current regulator. That would be more simple and efficient.
Click to expand...
Perfect. I guess that will have to do. I can only make so large a battery for this. I do want a a couple of the cells in parralel , because a 100 watt LED will consume a lot of current, though I wonder if the boost converter will be so inefficient as to make that entirely worthless. Maybe even 1 18650 ION cell would last a deciently long time? I can imagine this thing heating up extremely quickly.
 
One more question, more BATTERY RELATED vs ebike related! (Sorry) o_O(this is good practice, I want to build a reliable BATTERY SOON) I need to TEST my cells and FIGURE OUT how much CURRENT each cell has! I DONT HAVE ANY DATA!/last time I tried with the multimeter SPARKS flew!
 
would I be able to drill holes in a heat sink and be able attach this LED? IT looks like it has two notched ends on it for that purpose. I am also think I could use a 20 volt battery LION 18650 5s to power this thing. Could I use my 18.2 V 3.5 amp laptop charger to charge the battery? I want to buy a really cheap BMS to use for this project. I don't have a lot of cash for this. Looks like the LED is only $3? If this works I am never going to buy a headlight from anyone again lol. This and the voltage regulator are only going to wind up being $10 (Plus BMS of course) I can always spend more if it works and get a reflector and lens if I want longer throw. I just wonder how hot it's going to get. 77F by the look of the tempurature test?(chart)

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E-HP said:
Add some velcro to the back of this and on your helmet, and plug it into your battery pack:
Click to expand...
Only problem is I need to use it off and on the bike. Because it's mostly if I get a flat at 2am and need to fix it. Helmet will way down my neck when Im stooping, bending, contorting, cussing, the thing weighs down on my NECK! ALSO...

THAT's BORING! and IM trying to make my first battery! I'll probably keep it simple a 5s. I eventually plan on making a HUGE battery for a bike. ALSO...

DO you guys just SKIM through EVERYONES post and comment? I guess that's one way to get to 1 GW...
 
MarkJohnston said:
Only problem is I need to use it off and on the bike. Because it's mostly if I get a flat at 2am and need to fix it. Helmet will way down my neck when Im stooping, bending, contorting, cussing, the thing weighs down on my NECK! ALSO...

THAT's BORING! and IM trying to make my first battery! I'll probably keep it simple a 5s. I eventually plan on making a HUGE battery for a bike. ALSO...

DO you guys just SKIM through EVERYONES post and comment? I guess that's one way to get to 1 GW...
Click to expand...
I did the LED light building hobby for about 4 years. I have a big tool kit of drivers, reflectors, heat sinks, lenses, and everything for building them. In the end it’s cheaper to make them if you want a specific application (driver with certain features or specific reflector or lenses), but if you don’t have specific needs, off the shelf is usually easier and cheaper without looking dorky. At least I never have to look around my house for a light. It’s also when I started learning about 18650 cells, and even for lights, brand and model vs Chinese generic makes a big difference.

9000 real linens is too much to do work with. There is a point where a light is too bright for an applicaton. You need a constant current driver not a regulator. There are a few good forums for info on LED light building that are ptretty helpful, if they are still around; it gets a little nerdy, discussing the next new LED being developed, etc. budgetlightforum.com was a good one for the basics.
 
E-HP said:
I did the LED light building hobby for about 4 years. I have a big tool kit of drivers, reflectors, heat sinks, lenses, and everything for building them. In the end it’s cheaper to make them if you want a specific application (driver with certain features or specific reflector or lenses), but if you don’t have specific needs, off the shelf is usually easier and cheaper without looking dorky. At least I never have to look around my house for a light. It’s also when I started learning about 18650 cells, and even for lights, brand and model vs Chinese generic makes a big difference.

9000 real linens is too much to do work with. There is a point where a light is too bright for an applicaton. You need a constant current driver not a regulator. There are a few good forums for info on LED light building that are ptretty helpful, if they are still around; it gets a little nerdy, discussing the next new LED being developed, etc. budgetlightforum.com was a good one for the basics.
Click to expand...
It doesn't seem that hard. I'm not going to go with 9000 lumens anymore.... This will be a crude but very practical device. No one will see me with it because headlamps hide your face with a giant beam.
 
MarkJohnston said:
It doesn't seem that hard. I'm not going to go with 9000 lumens anymore.... This will be a crude but very practical device. No one will see me with it because headlamps hide your face with a giant beam.
Click to expand...
It's not hard. The concepts are simple, so the LED light hobby got boring fast. The lights were fun when going camping, since pointing the beams with the right reflectors into the air seemed like the beam would go forever, like a light saber and you could see the beam against trees a mile away.
 
Here's the finished product, if anybody is interested... Works pretty good so far, really had to jam the lid shut down on the wires, hope I didn't nick anything...

Super bright ! But I definitely wouldnt want to add any more LEDs, it gets warm with just the one.

I will say this took a TON of time, by now that I know I can do this, I can build any battery I want... Though I do say that with reservation, seems larger batteries take emore focus, patience and get more technical...

Yeah definitely cheaper to grab a black diamond headlamp for $50 off the self like others said on here, the time consumption here was insane. Also My materials cost for this was $20 for best budget BMS and LED DRiver. Not sure if these lower quality will fail, BMS is chinese and so is driver. I got a free charger by complaining at ALI express.The plus here is that this thing is jammed so tight together its pretty drop proof, though a plastic bad over it and its waterproof and expedition ready lol

But I will use this as a back up light and my work light for my ebike only. I have been stranded out on roads fixing stuff before in the dark of night 3am. Out here, there are no street lights.

I couldnt make it an all in one. Initial tests show the light can go 5 hours!!! Huge battery! It could probably be on for 8 hours and would just be dim, still usuable though

Will probably post a pic of brightness once it gets dark
 

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