Can I parallel 2 lights?

[Momato]

Hi All

I have two triple cree lights with bFlex current controllers. I normally run them at 1A each from 14 V Li-Ions. Now, since I am building a new light, I wondered If I could run these two "old" ones in parallel at 500 mA from one battery? Just because two run at 500 mA should be more efficient than one at 1A...

Let me know what you think

Best regards, Morten

 

[Buck91]

I don't know much about running drivers in parallel but I know running emiters in parallel can cause issues since its virtually impossible to get identical vf's. Drivers though, may be a differen story.

 

[Jarl]

2 drivers in parallel is fine. (and very handy if you're hitting the current limit of 1 driver- just lob another in)

2 in series gets messy, though!!

 

[Momato]

yes, that is what I thought. Will there be a noticable difference in light output when running 6 leds at 500 mA instead of 3 leds at 1000 mA?

And does anyone have nice ideas for a 6 led setup (a housing)? Now, I am using the Achesalot design....

 

[Jarl]

I'd say, yes, there will be, but I'm quite a fan of ridiculous numbers of LED's at ridiculously low power for ridiculous efficiency. Plus the fact you can then whack them to full power for ridiculous amounts of light :devil:

 

[znomit]

yes, that is what I thought. Will there be a noticable difference in light output when running 6 leds at 500 mA instead of 3 leds at 1000 mA?

In my fav post on CPF jtr1962 details R2 lumens vs current and power.
You get 20% more light, and 5% more runtime. :thumbsup:

 

[steve6690]

I reckon it will work quite nicely. Recently I was testing a 6 x Q5 head with a bench power supply to see if there was any value in driving the string at 1A instead of 700ma. I concluded that the difference in light performance was not worth bothering with, in fact I and my wife found it hardly noticeable. When you consider the extra heat you need to deal with it becomes an easy design decision to make IMHO (and in the context of my design requirements).
I also tried other current levels. Runnning the 6 x Q5's at 500ma produced easily enough light for a bike light, and while it was noticeably down on output from 700ma, there was still plenty of useable light.
Two parallel strings of led's, driven by one driver, all in one bike light housing. I think someone has done that on here already, albeit with more led's, and it worked very nicely. I think they added red leds too...