how to drive 6x Xpl-Hi in parallel

AmberFlo · 2019-09-06T07:00:53.000Z

hey, i want build mobile worklight powered from 18650, i want use 6x xpl hi, one led needs about 3A so 6x3A=18A so driver must output 18A, so i have 3 question.

on datasheet of xplhi i see that vf is about 3v it means that it if i provide for led 3v and 3A i get max output of lumens? so after you cross 3V only A decide of lumens or i must provide more V ?
i didnt see driver that is capable providing 18A , so can i use some cheap china step down or buck converter that convert 4,2v from multiple 18650 to 3v and output 18A?
should i use 18650 parallel or in series ? what will be more efficient ?

kiriba-ru · 2019-09-06T07:18:13.000Z

Hi.
Do you have any flashlight with 3amp powered xpl-hi?
What optical system (reflector, TIR, mule or matted plastic) are you going to use?
Do you have heatsink good enough for 60W of heat?

You need a driver that limits current. Im not sure you need 3A per led, this current is good for flashlight but seems to big for other uses. Driver input voltage should exceed led voltage at current needed.
This is not great idea, this converters are great for diy but efficiency and reliability are not good at all.
Series connection is usually better. With series connection you avoid big currents, all wires and connections are not overloaded.

AmberFlo · 2019-09-06T07:24:04.000Z

so i can wire emitters in series?

KevinZA1988 · 2019-09-06T07:26:32.000Z

If you get a 2A 24VDC driver you can connect them in series. At 2A it will produce around 700 lumens per LED at a Vf of 3.32V. That’s over 4000 lumens in a 6 LED setup.

KevinZA1988 · 2019-09-06T07:27:42.000Z

At 2A in series the for 6x XP-L HI the Vf should be around 20V.

AmberFlo · 2019-09-06T07:41:10.000Z

ok, so best will be connecting led in series, and 18650 also in series, and then step down to 20v right?

KevinZA1988 · 2019-09-06T07:55:04.000Z

If you use protected 18650 cells you can SAFELY connect 6 in series, so in theory your voltage will range from 24V on a full charge to 18V empty. But it actually depends on the driver you are going to use. Sort that out first, then decide what you are going to do for a power source. At led4power.com you can get a 8-12A 3V LED driver so you can supply any amount of LED’s in parallel with 12A combined current. So if you want to use 6x XP-L HI it will be 2A per LED. If you go that route, you can connect your cells in parallel too… Very easy setup.

https://led4power.com/product/ld-a4-2-12amp-17mm-constant-current-led-flashlight-driver/

But, heat on the MOSFET on this driver can cause it to trip on high power parallel setups, so you should think about adding a silicone sheet and a copper plate on the driver to dissipate heat from the MOSFET.

KevinZA1988 · 2019-09-06T07:57:48.000Z

How does the setup look that you want to use the 6x XP-L HI with? A custom made thing? Otherwise you can use other products at led4power.com to make a very reliable running high power parallel setup using his products as a base to design from.

KevinZA1988 · 2019-09-06T08:00:53.000Z

And here is XP-L HI test that has a good chart to use as reference: XP-L HI 1A V2 LED Output test by Texas_Ace, Well, you have seen the HD, this is the HI. It is exactly what you expect.

AmberFlo · 2019-09-06T13:05:31.000Z

but making it cheap cant i just use lets say 6x18650 connected in series so i have 25V then use step down to make it 21V so each of 6 led should receive 3,5v and set the current limiting on step down to output only 2A with 21v so it will produce 42W for 6 leds. ofc led will be connected in series