What does it take to drive a C2000 off a 12V power source?

[numbski]

Hello... :) So, until I visited this site it was my perception that to drive an LED, you provided the right power input, provided a proper resistor (don't know the calculation for the "right" resistor off-hand), and off you went. The concept of the proper driver never occurred to me.

That said, the C2000's are an odd duck. They can take 12V input, put they're much happier between 16-18V, and they want 1.8mA. So it seems to me that in order to use a pair of these on my motorcycle, I'd need a 12V step-up convertor to get me into the 16-18V range, and then some way to regulate it to 1.8mA. I've seen all kinds of enthusiasm around here, bu nothing about how to properly drive these beasts.

Help welcome! Kthanks! In the meantime I've ordered 2 P7's for my low beams using a hipCC buck convertor to drive those. I figured I could go to 2 or 3 P7's on each side if I needed to go from low to high (cutoff notwithstanding, of course!), but running a pair of P7's for low and C2000's for high beams is an interesting concept too.

BTW - I'm thinking that if I went the home-grown route, I could build up something like this:

http://obs.nineplanets.org/meade/1812/1812.html

Only concern with that is that it's limited to 3A output, which means to drive two, I'd have to build two - unless I'm okay with limiting the LED's to 1500mA each. Also have to do an outstanding job of heatsinking both the circuit and the LED's themselves.

 

[VegasF6]

This post is confusing to me:

That said, the C2000's are an odd duck.

Do you mean the bridgelux C2000 here?

They can take 12V input, put they're much happier between 16-18V, and they want 1.8mA.

You must mean 1.8 amps, not mili-amps??

So it seems to me that in order to use a pair of these on my motorcycle, I'd need a 12V step-up convertor to get me into the 16-18V range, and then some way to regulate it to 1.8mA.

Again, amps, not mA. What kind of motorcycle are we talking about? Street or dirt? An actual alternator? Expect ~13.6 volts or better, but a pretty dirty power. In the data sheet I am looking at, typical Vf 13.2 at 1300 mA. Not that I would suggest direct driving from the motorcycle battery.

Help welcome! Kthanks! In the meantime I've ordered 2 P7's for my low beams using a hipCC buck convertor to drive those. I figured I could go to 2 or 3 P7's on each side if I needed to go from low to high (cutoff notwithstanding, of course!), but running a pair of P7's for low and C2000's for high beams is an interesting concept too.

BTW - I'm thinking that if I went the home-grown route, I could build up something like this:

http://obs.nineplanets.org/meade/1812/1812.html

Only concern with that is that it's limited to 3A output, which means to drive two, I'd have to build two - unless I'm okay with limiting the LED's to 1500mA each.

In the case above, are you talking about the P7s or the C2000s?
[/QUOTE]

Is this planned for on road driving? I assume you are aware of the legal problems and safety problems you face here?

 

[numbski]

You are of course right on all counts. I was reading 1800mA and thinking 1.8A and it came out 1.8mA. :P

I'm aware of the legal and safety stuff, yes. Doing all kinds of reading on what is legal and what is not, and also what is safe vs what is not. It will be used on-road. If it's not safe, I won't use it, pretty straightforward. :)

Those issues aside, I somehow got that idea that driving the LED straight off the battery was a "bad idea", so I needed a driver board. Yes, I am talking about the Bridgelux C2000's. For the moment I have already ordered P7's and a hipCC buck driver. The homegrown upconvertor would be for the C2000's, and I'm thinking I'd have to build two - one for each LED.

Anyway, cheating and using an led calculator, if I provided 17V source voltage, then I'd need a 1ohm, 3.1 watt resistor. Of course I'm only providing 12V, not 17V - said calculator says the LED won't light up at 12V. :)

 

[VegasF6]

Yes, but I suggest you check voltage at the battery of your motorcycle while running. Perhaps with and without lights on, and at different RPM's. Expect to see as much as 15 volts. (GM cars in particular are known for producing high voltage)

Also keep in mind that while starting expect voltage to drop, probably as low as ~7-8 volts! That can be very tough on electronics. I know on my bike at least, the headlight is disengaged while starting, so that is a good thing :thumbsup:

Automotive is a little out of my field, but I am slightly concerned with AC voltage leaking into the system as well. I guess it shouldn't, that is the job of the rectifier on your bike, but I would check for AC at the headlight circuit anyhow.

Sorry I can't be more specific with how to regulate those LEDs but I might just try hooking them up direct and monitor current. Perhaps put a 2 amp fuse inline while testing, if you can find one.

One option might be the Shark, or Blue Shark step up converter, but max current is listed at 980mA.
http://theledguy.chainreactionweb.com/product_info.php?cPath=48_49_61&products_id=721

Perhaps if you take it up with Wayne in his forum, he would have a suggestion?
http://www.candlepowerforums.com/vb/forumdisplay.php?f=38

 

[clint357]

CCHIPO at 2.5 amps will give you about 3000 lumens and will stay stable with good heatsinking.