Looking for options to drive a pair of XHP70.2 off 12V DC

Rennfab

New member
Joined
May 9, 2021
Messages
2
I started a little LED upgrade to a small motorcycle headlamp assembly here. The factory unit is a LED assembly with an internal driver, however it puts out a paltry amount of light during night runs. I purchased a pair of Cree 12v XHP70.2 LED's, modified the heatsink to mount them in behind the lenses, and wired them(in series) to the driver. However when powered up, the system does not illuminate the LED's. They very dimly flicker at about 20-30hz.

Now I am no LED expert, but I am assuming that this means that the driver doesn't output enough current to illuminate them, so that leaves me having to power them via an external source. So I am here seeking advice on what drivers are available to run a pair of XHP70.2 LED's, 12-14V DC input. I don't need to overdrive these things at their max rated current, just looking for something that will drive them at an optimal level of output. Heck I suspect that even at 50-60% of their rating will be far greater than the OEM module that was in this headlight. I have done some google searching online, but I honestly don't know what is good/bad, what to avoid, etc, etc.

Preferably, I'd like to find something that has a fused 12V main input from the battery, and possibly a relay trigger that I can hook to the original low beam wire(either the switch or maybe the original driver) so that the hi/lo switching still works. I have to be able to seal it away from the elements, so that means I have to be able to either pot it or put it in a sealed enclosure. Having to build/solder it isn't entirely out of my capabilities(kit form) but I would need to know exactly what components to purchase and a clear schematic to work from(and maybe a few questions here and there answered) I do have to drive two of them, so I don't know what a decent amperage for these should be. Maybe 3-4 amps total at 12v?

Basically just looking for some input here on what to do or where to look/buy. Or should I buy the 6 Volt option xhp70's and work off a drive that doesn't 12V in put/6V output?

Thanks!
 

Dave_H

Well-known member
Joined
Nov 3, 2009
Messages
585
Location
Ottawa Ont. Canada
Sounds like the driver may not be able to deliver the voltage needed to drive two 12v LEDs in series. Driving in parallel may be an option but I would defer to someone who knows more and has done this.

Can you determine specs for the original LEDs and driver? If you are connecting different LEDs to the same driver, important to know, or find out as much as possible with some testing, if old LEDs and driver are still working. I could describe this.

This thread should probably be in Transportation Lightning. I'm no expert but be careful about regulatory compliance if used on-road.

Dave
 

Rennfab

New member
Joined
May 9, 2021
Messages
2
Sounds like the driver may not be able to deliver the voltage needed to drive two 12v LEDs in series. Driving in parallel may be an option but I would defer to someone who knows more and has done this.

Can you determine specs for the original LEDs and driver? If you are connecting different LEDs to the same driver, important to know, or find out as much as possible with some testing, if old LEDs and driver are still working. I could describe this.

This thread should probably be in Transportation Lightning. I'm no expert but be careful about regulatory compliance if used on-road.

Dave


So the new Cree XHP70.2 LED modules are rated 12V at 2400mA. I cannot find any specifications on the factory LEDs. I did test the Cree's off a power supply at 12V/1amp and tested the XHP's separate and together in series. That voltage and current lights them independently, but not in series. Stepping the current up to 4amps at 12v causes the flickering just like it did when I wired them to the factory driver. So I went and made a pigtail and tested the stock headlight driver while powered up on the bike and it outputs ~16volts at .97amp, so definitely not enough to drive these newer LEDs.

So I either have to step down to a less powerful/compatible LED module, or I have to wire in external LED's drivers to run these. Or maybe wire them in parallel like you mention. Just not sure what is the best route to take. I did look up some other drivers and found these Mean Well LDD Step up/ Step down up sealed drivers. Not sure about their quality though(they're pretty cheap, cost wise)
 

Dave_H

Well-known member
Joined
Nov 3, 2009
Messages
585
Location
Ottawa Ont. Canada
XHP70.2 is characterized at 12.2v max. and 1.05A (12.8W) each. Maximum at 1.2A approaches 15W each. That's a lot of dc, optical power, and heat to manage. Your present driver is definitely "boost", maybe "buck-boost", can handle at least 16W which is enough for one Cree at 12v not quite maximum power (1A), or two in parallel at somewhat below half-power each. Would that be enough?

If you were to run two at full power, with another driver, is your heatsinking sufficient i.e. keep the LEDs at +85C or below? Might be hard to figure out analytically. Looking at efficacy, count on roughly half the dc input power to go into heat.

If the driver circuit is visible, can you post an image and/or identify driver chip(s) and markings?

Dave
 

DIWdiver

Well-known member
Joined
Jan 27, 2010
Messages
2,685
Location
Connecticut, USA
This thread should probably be in Transportation Lightning. I'm no expert but be careful about regulatory compliance if used on-road.

Dave

No care needed. There is absolutely no way you can legally use a modified light like this on the road (on a motor vehicle).

Because it's illegal, forum rules say you can't even discuss it. The moderators are really adamant about this. Go to the Transportation Lighting section and see how many threads they have shut down.

That section is also a great place for advice on what you can and should do, and why.
 

Dave_H

Well-known member
Joined
Nov 3, 2009
Messages
585
Location
Ottawa Ont. Canada
No care needed. There is absolutely no way you can legally use a modified light like this on the road (on a motor vehicle).

Because it's illegal, forum rules say you can't even discuss it. The moderators are really adamant about this. Go to the Transportation Lighting section and see how many threads they have shut down.

That section is also a great place for advice on what you can and should do, and why.

Fair enough, good reason why I'm directing OP towards Transportation (Automotive/Motorcycle) forums. I'm reminded of the sensitivity of this topic. However, how these LEDs can be used can be applied to other non-automotive uses. As for off-road versus on-road use, I'll leave that one for now.

Here is an interesting, somewhat related thread, gives a taste of the level of complexity of this subject:

https://www.candlepowerforums.com/v...-Hella-motorcycle-lights-remmendations-needed

The 12v "auxiliary" LED lighting products I am somewhat familiar with appear not to be certified for on-road vehicle use; but still useful for other purposes, down to lighting up the back yard with a solar charged battery; topic for other thread(s).


Dave
 

DIWdiver

Well-known member
Joined
Jan 27, 2010
Messages
2,685
Location
Connecticut, USA
Yes, there are plenty of threads there talking about lighting for off-road use. You just need to be clear that it is for off-road only, and not in a 'wink-wink, nudge-nudge' way or they'll shut you down.
 

Latest posts

Top