Wonderful!
I hope to try soon!
thank you again!
Awesome.
I cannot wait till this driver is available for everyone to buy.
There is nothing else out there quite like it.
Great!
I hope to see it in soon!!
Won’t want to miss that!
Updated OP with some details,giveaway here:
I am assuming these will be available for purchase after the giveaway?
Thanks! Glad to see this coming into reality. The features and performance of this driver look outstanding!! The overheat protection setup seems quite original. I love the e-switch support! Mode choices are quite well thought out.
Maybe I missed it, but I don't see any strobe mode. Most of my lights support it. It's been proven to be the best mode for self defense. I've heard it from actual home break-in's to Special Ops guys. It's not worth much though if not easily accessible, and certainly doesn't apply to all flashlights. I prefer to include it only in larger, brighter lights.
If you decided against to include strobe in the design, that's fine, but will somewhat limit my potential use of this driver. I have many people ask for it, not all for sure - some see no value in it whatsoever.
No,I must order parts and pcb-s,and that means 4-5 weeks.
Yes,no strobe or other blinkies for now.I'm no against strobe,the problem is, so many wishes and just one switch.
Would you consider putting in a hidden strobe?
That way it’s completely optional to see and for those that don’t use it, they’ll never even know it’s there.
Maybe something like 6 or more very fast taps. Set up like the programming mode of DrJones drivers.
Just a thought, this driver still has everything I’m looking for and I’m excited to see it brought to market!
So a week or so after the giveaway? I can wait.
I did some tests yesterday.
It was battle between nanjg(3 Amp version) vs. this driver (PWM vs. PWM-less) at low currents.
I used xm-l u2 on heatsink with small tir and hs1010A for lux measuring(at some distance).
First,I measured current and lux for nanjg at low (5%) mode:
Current:151mA
Lux:2620lux
Then,I did the same with this driver(current is as close as possible):
Current:153mA
Lux:3480lux
That's ~33% increase in brightness compared to 3Amp nanjg at same current.
Similar,I wanted to see at which current this driver will have the same brightness as with 3A nanjg:
Current:115mA
Lux:2600lux
3A nanjg consumes ~31% more current to get the same brightness.Same result as test #2 if we consider measurement errors.
Answer to question why this happens is:
Efficiency of xm-l u2(from cree pct) at 3Amp,25C: 98lm/W
Vf of xm-l u2(from cree pct) at 3Amp,25C: 3.34V
Efficiency of xm-l u2(from cree pct) at 0,150Amp,25C: 165lm/W
Vf of xm-l u2(from cree pct) at 0,150Amp,25C: 2.68V
Nanjg runs led at 3Amp on every mode,this driver runs led with constant current(no pwm).
Overall efficiency gain can be calculated as: (165/98)*(2.68/3.34)=1.68*0.80=1.34 or 34% which is very close to measured values.You can see that led is 68% more efficient at 150mA vs 3Amp,but driver burns more voltage because lower Vf of led at 150mA.Overall,gain is still pretty impressive.
BUT,to be fair this test should be 5Amp stacked nanjg(or DD fet driver) vs. this driver,since this is 5Amp driver.
Similar to upper calculation (this time I used some numbers from match graphs,since cree don't show 5Amp numbers):
Efficiency of xm-l2 u2 at 5Amp,25C: 84lm/W
Vf of xm-l2 u2 at 5Amp,25C: 3.8V
Efficiency of xm-l2 u2(from cree pct) at 0,150Amp,25C: 188lm/W
Vf of xm-l u2(from cree pct) at 0,150Amp,25C: 2.8V
Overall efficiency gain can be calculated as: (188/84)*(2.8/3.8)=2.23*0.74=1.65% or 65% increased brightness for same current or reduced current to get the same brightness.
And 65% reduced current means at least 65% longer runtime (that's like you have panasonic 3400*1.65=5600mah).
This is example for just one low current (150mA),but conclusion is pretty obvious.
When you consider one more important fact,that 5Amp pwm driver losses regulation very quickly(because of high Vf),pwm-less driver can maintain constant current/brightness until battery is empty (again because of very low Vf at low currents),advantages are even more clearer.
Edit:
Let's consider one more case: 5Amp buck driver(pwm regulated) vs. this driver.
You'll expect that buck is always superior compared to linear when we talk about efficiency.Let's assume 90% efficiency for buck.
At low mode (for ex. same 150mA) we have next data for buck driver which is pwm regulated:
Efficiency of xm-l2 u2 at 5Amp,25C: 84lm/W
Vf of xm-l2 u2 at 5Amp,25C: 3.8V
Driver efficiency:90%
Input voltage:4.2V
Led power=0.15A*3.8V=0.57W
Battery power=(1/0.9)*0.57=0.63W
Current draw from battery(voltage depended,using 4.2V)=
=0.63/4.2=150mA
I used 4.2V because this way I got same batt. current as lin. driver,so it's easy to compare.
Led lumen generated=84lm/W*0.57W=48lm
_______________________________________
This driver:
Efficiency of xm-l2 u2(from cree pct) at 0,150Amp,25C: 188lm/W
Vf of xm-l u2(from cree pct) at 0,150Amp,25C: 2.8V
Input voltage:4.2V
Led power=0.15A*2.8V=0.42W
Battery power=0.15A*4.2V=0.63W
Driver efficiency=2.8/4.2=67%
Current draw from battery=150mA
Led lumen generated=188lm/W*0.42W=79lm
So,at same battery current of 150mA 90% efficient pwm regulated 5Amp buck driver will generate 48lm,while pwm-less linear driver will generate 79lm.That's 79/48=1.65 or 65% more,same as above calculation for 5A nanjg or DD fet drivers.
Note that linear driver efficiency is just 67% vs. 90%,but 188lm/W vs. 84lm/W of led efficiency totally changes final efficiency result(and that only matters).
The point of this calculation is to show that there is no advantage of having high current 5Amp buck driver(at least not for single li-ion),unless it's also pwm-less controlled(as we can see from various driver threads,even much simpler pwm controlled buck is PITA,not to mention size and cost).Also,that hypothetical buck driver looses regulation very quickly,since it can't increase voltage.
Stop showing off and take my money! :D
Led4power, really a great driver, I'm sure we all would appreciate something like this!
Since there isn't something as "enough", I'm going to ask the questions:
1) Would this be able to run a MT-G2 with the Zener mod done? (in other words, is it zener mod compatible?)
2) Changing the sensing resistor, what is the maximum amount of amps the board will safely take? I'm thinking 3 x XML2 (in parallel) driven from 1 x 26650.
Thanx, really looking forward to the release ;)
looks like the driver does as expected, nice!
Personally, I'm not that picky on constant regulation, I sort of like direct driving a flashlight with the output dimming as the battery drains, like the good old incan days :-) . But I do like efficiency a lot, that would be my reason to use this driver.
Nice very very nice…quite efficient!
1)zener mod doesn't work correctly with this driver because driver constantly adjust some parameters based on battery voltage to maintain costant current during discharge.
Something like this would work:
2)It's hard to tell,heat in mosfet and sense resistor are limitations,and they strongly depend on how good driver is mounted/cooled,voltage difference between battery-leds,and amount of current.For mosfet there is a point of max. dissipation,where (Ubatt-Uparasitic-Uled)*I=max.For example you'll expect that max. disipation is at max. current,but it isn't.
In my tests,driver driver dissipates more heat at 1.1amp than at 5amp,and that's because led needs more voltage,so less voltage is burned in mosfet.
On the other side dissipation in sense resistor is I^2*R.I use metal alloy 1206 sense resistor with 1W@25C rating(this is much more than common 1206 resistors-0.125W).
It depends on all that.
Wow!!
I will take at least 10 drivers.
-modes: 0.3–1.5–20–100,standard half press to increase mode
-“turbo” mode option (140%4.2V,drops linearly to 110%2.8V),turbo enable via solder moon 2
I’m not quite getting this turbo mode. The driver is rated for 5A. So I would assume that 100% = 5A. How can turbo be higher than 100%
Is the 100% level less than 5A?
Is turbo just a timer to drop back from 100%?
Wait a second, why did you take an efficiency of 84lm/W (corresponding to 5A) for the buck driver?
In a buck driver, if the average output current is 150mA, the current will vary around that value in a sawtooth shape. The current to the LED will be very close to 150mA all the time.
Even if the ripple is very bad (caused by a too low value inductor), let’s say that the max current is 300mA and the minimum current 0mA (averaging 150mA), the lm/W value to take will be very close to 188lm/W.
I agree that a buck driver uses PWM, but it’s only to control the FET. The inductor smooths things out and the output current is very stable. That’s the whole point of a buck driver.
Either you did a mistake, or did I missed something?
I took this picture out of HKJ review of a buck driver which clearly shows the sawtooth shape and minimal ripple. There is not axis annotations and values for the current unfortunately. 
The blue curve is lux, measured with a photo diode, not current. There is no annotations, because the values are completely uncalibrated.
Generally buck and boost drivers delivers a smooth current to the led, but there are exceptions.
And sometimes pwm is used for brightness regulations.