how hard can i drive an xr-e emitter?

[PilotPTK]

@texaspyro

@PilotPTK

You could put 100A (yes, 100) through an LED (XPE, XRE, XML, XPG doesn’t matter) if you had enough voltage. It wouldn’t survive for more than a microsecond, but you could do it.

Been there, done that. Actually lasted at least a millisecond…

Hehe… yeah, I’ve done it a few times as well… Fun to watch for that millisecond

Mains voltage through a bridge rectifier? That’s how I most commonly pump a gazillion amps through an LED unintentionally…

PPtk

[GottaZoom]

@PilotPTK

@Pok

@Pulsar

so today i swapped the driver in the tf-r2 to a nanj 2.9a driver… but its still only pulling 1.96a at the tail. ive got 4 solder points to the pill, and set to three mode. any idea why?

XR-E Vf is high, when you drive at 2-3A Vf near 4V.

Yep, exactly. To drive an XR-E harder than about 2A, you’ll need to use a switch-mode buck driver and power it with (most commonly) 2 Lithium Ion’s in series.
A single LiIon can’t maintain enough volts to push more than that through an XR-E. An XM-L can be driven much harder with a single cell because it has a lower Vf.

PPtk

Missing PPtk posts recently.

Just put a dedomed XRE with a not-great East092 driver and it’s pulling just under 1.5A with protected UF3K (chosen for high resistance and protection in this test) in a SF L2. This driver went up to about 2.8A on high with an XPG2, assuming my memory is close. I’ve seen others say other LEDs will pull less hard after being dedomed.

So my guess/question is does the result sound reasonable?

I was concerned that starting with an Sony IMR might be too much, but it looks like that should be OK on high (direct drive?) now that I know the drop-in works?

[comfychair]

If it's too much they'll give you a good warning by turning blue before any damage is done. Just start with running it a few seconds at a time, gradually running it longer each time, and watch for it changing color.

[Pulsar]

From what I was told, the VF keeps the XRE right around 1.8-2a even direct drive from a single cell. I have had a few XREs pulling 1.8 dedomed and they seemed to hold up fine. Anything more than that you will need multi cell and a buck driver

[comfychair]

I've swapped a 2800mA 105C into an XR-E light as a 'hell, why not?' experiment, before completely gutting it to replace everything with good parts. From an ordinary grey 4.2v Panasonic 2900 (new laptop pulls) it did 2.70A at the tail, and the LED seemed to handle it with no issues.

[GottaZoom]

@comfychair

If it’s too much they’ll give you a good warning by turning blue before any damage is done. Just start with running it a few seconds at a time, gradually running it longer each time, and watch for it changing color.

Seems to still be doing good @ 2.3A on a freshly charged HiMax (one of my lower resistance protected cells). The L2 is one of my higher resistance hosts, so I’m sure it will go higher. I probably shouldn’t but … well, you know ….

Kinda like the tint on this one (though not pure white it beats angry blue!). In a OP reflector it has an graduated hot spot - real tight & hot in the center with less intensity aroundf before falling off to spill. Built up to use with a fixed aspheric that came with an XML driven @ 2A in a different body; it will be nice to compare and swap around.

Edit: KP3100 does just over 2.5A and Sony IMR does 2.7x still in the L2, and led still doing oK. It’s on alum from an SK68, so it might not last long.