You could also use a triple XPG2 as the test LED, to mostly avoid the high-Vf-limiting-max-current issue.
HKJ, I was agreeing that the comparison should be based on lumen output rather than just current but that does make for a more complicated test.
I also plan to do the comparison based on light output, but I’ve not receive my sample yet.
You can do a fairly good estimate without doing the test, but if you have a 5A pwm driver it is not that difficult to setup:
Mount the led and a luxmeter at some fixed position (A luxmeter with PC logging is preferred).
Run the test with the pwm driver.
Use the LD-1 in ramp mode and adjust it to same brightness on luxmeter.
Replace battery used for adjustment with fresh battery and run the test again.
It could be interesting to do, but I do not have a 5A pwm driver for it.
Hhmm, gotta check my driver stock. I could build up a Nanjg to ~5A, but I do have this driver from Richard: http://www.mtnelectronics.com/opencart/index.php?route=product/product&path=67&product_id=214, but it's 2-3 cells. Didn't realize you gained 50% over a PWM mode - I knew it was better, but not by that much - cool!
That is because the XM-L2 has low efficiency at 5A.
I wonder what the efficiency difference might be at 1.4A, or 1.5A, or 1.9A.
The 1.9A light I just put together with a Nichia 219B is really nice, and the PWM is fast enough it looks almost the same as full current control… but the runtime won’t be as long. I never really use it above 800mA or so (average), so I could reduce its overall power to increase efficiency, but it’s nice having a turbo mode once in a while. The higher power is also nice for strobes, because a 0.3ms pulse looks brighter at 1.9A than it would at 1.4A.
For a bike tail light, I went with 700mA because djozz’s measurements show that as more efficient than 350mA or 1050mA on a red XP-E2. I don’t need it that bright, but it should increase the overall runtime at the same brightness levels, even when using PWM.
The efficiency difference is because a 50% (or whatever) constant current requires a much lower Vf, compared to a PWM'ed 50% which is full current for half the time and none for half the time (assuming both drivers do the same current at 100%). The average current might be the same for both drivers but the voltage isn't and the total power used comes from both volts & amps.
Update added to OP. I'm probably not going to have time to do battery time tests, least not as thorough as I'd like.
Thanks for all the testing Tom E. You are trend setting here.
Im still waiting for mine. Nothing in the maibox today either. :_(
Getting my fix here in the meantime. No need to rush the review though.
Just fyi... I wasn't sure how turbo mode works. He is saying basically it's DD - very high amps, more than the 140% increase he listed. Basically turbo takes it out of current controlled/limiting mode -- this is a very nice feature!
Also, HKJ found an issue in high mode using higher powered cells that needs a cap to be replaced, and once done, fixes the issues that HKJ was seeing. So, I'm holding off more testing til I get the cap and can mod the driver. It's a tiny 0402 -- I never worked with a cap that small, so may have a "super tech" at work do the replacement. He would have no problem doing this, so less risk than me doing it 
.
This HD2010, btw, is a total PIA for this experimenting because of the poor clearance for the bigger wires, big flat reflector bottom... Also the plastic LED alignment piece they ship with HD2010's now is too small for the opening, making it almost impossible to center the LED... Ugh. The older HD2010's I have didn't have this promleb- the LED alignment pieces fit much better.
Is this driver listed as something besides LD-1 on Intl-Outdoors?
I see 18 drivers there and don’t see this one.
Would this work well in a BTU Shocker host?
http://www.cnqualitygoods.com/goods.php?id=1818
Off topic:
Would a 60 Watt Weller temp controlled (700 & 800 degree F tips) soldering station work OK for reflowing LED’s?
It’s a new linear driver by Led4power that does not use pwm for dimming so it has much better efficiency at lower currents. No relation to IO.
Thanks Rufusbduck
Meant to put it in the original thread.
That where they talk about it being sold by IO.
That’s refer to XM-L2 on copper, that HKJ probably need if he damage his leds while doing testing the driver.
Updated the OP with new tests of batteries, and enabling turbo mode. Also tested the medium against a PWM based medium mode in a Nanjg driver configured at 4.2A.
LD-1 has 10mohm sense resistor in current path,even on turbo,that's 50mV extra voltage drop.Could you post a pic of your setup,especially at which place on driver you soldered negative wire?Best place is very close to sense resistor(otherwise gnd ring will cause extra voltage drop that can be higher than 50mV).
Also very nice test Nanjg vs LD-1. It's important to note that results will be even better(worse for pwm) if that nanjg had 2 extra chips,because LED efficiency is worse at 5A vs 4.2A.
Thanks for doing the LD-1 / Nanjg efficiency conparison, saves me from doing that :-). The driver does what theory promises.
Not being able to get much over 5A on Turbo using a single li-ion is consistent with my numbers, to get over 5A the voltage at the driver connections must be almost 3.8V, not many batteries can keep up 3.8 V at 5A load for long, and in a flashlight there's even some voltage loss before the driver (spring, switch).
I mostly use modes in the 1 lm to 10 lm range, sometimes 0.1 lm or up to 50 lm, and more like 100 lm to 200 lm for biking… but anything above that is pretty uncommon for me. So, more efficient low/med modes sound very interesting.
Looks like this should be able to get about 40% or 45% longer run times on low/med modes, compared to PWM. Maybe less on lights which aren’t driven as hard, and more on lights with a higher maximum.
With PWM above 10 kHz, the output looks very similar to true current control… but the runtime is still shorter. I don’t mind this very much on 1x18650 lights, but it’d be really nice to get a current-controlled driver for smaller lights like 1xAA or even 1xAAA.