I’ve finished my new bar light but not sure how many lumens I’ve got…
It’s 2 x XHP70 6V in series running at 5a (at the moment) with a taskLED H6Flex driver.
Anyone care to show me how to work out what I’ve got? Pretty please…
Lumens is a measured not calculated entity. It can be estimated by the numbers, but it’s best measured through a metered system for accuracy. The optics in front of the emitter play a role in actual out the front lumens, so calculations based on power supply, current and driver efficiency are only a part of it.
You should probably be seeing around 4000 lumens, at a guess, but of course it’s difficult to really say.
Ah, I see, thanks for clarifying.
Would that be about 4000 per LED? It certainly ‘looks’ a lot brighter than my old, 7 XML, light :sunglasses:
Are the XHP-70’s set up in 12V then wired in series at 24V? For 5A at 24V? That would change things considerably.
Otherwise, I would expect the output to be in the 4000 range for the pair, or 2000 something each.
My P2 binned XHP-70 at some 11.7A 6V makes 7245 lumens all by itself. Likewise, in the L6 at around 5A the XHP-70 is doing some 3500-4000 lumens in 6V configuration and eating all 5 of those amps alone. Does that help?
2 x 6v in series @ 5a input current 
Well, they could be doing around 7000 lumens in tandem that way. Not sure how you’d get a true reading on such a light. Know anyone with a lightbox?
Unfortunately not 
I was guessing around 7-8000 so quite happy with that, thanks Dale :+1:
Dale how are you liking the L6 with the FET driver? I keep considering building some TA drivers for mine but just not sure the extra heat is worth it.
It does indeed make a lot of heat, at 11.7A it’s pretty crazy really. If you could resistor it back to some 9A or so it’d probably be all right… would still get hot unless it were cool out but it’d fare better and be more within it’s limitations both emitter and host.
For this one, with ramping ability, it’s easy to pull it back slightly… not encumbered by 3 or 4 mode selections. All in all I like it a lot, glad I used the ramping from TK though.
Edit: Different cells would probably be an easy answer. Just go with a cell that won’t deliver that maximum output. Or use something less than 18ga leads in the wiring. Or some of both. 