[Update]Wurkkos dual LEDs 21700 Headlamp design Photos/UI update~

……yes, that is the point about size and weight when we decide to use a 21700, for a input and output 21700 with more power and runtime…
Power and runtime depend on much more factors. For example from driver efficiency. So what kind of driver you will use?

As far as I was told, HD20's driver will use FET. The charging currents are 2A (recharging battery) and 1A (reverse charging from battery to external device). Please note that this is yet to be confirmed by Wurkkos/Sofirn.

Fet!? For 1500lm? I don’t think it is good idea. Buck or at least linear driver is needed here.

Thank you for all suggestion for HD20 and thank you Lux-perpetua to collect all information. And finally we have confirm the UI and the LEDs

Spotlight—Cree XPL 5000K
Floodlight—LH351D 5000K 90CRI

UI details (except the raming mode)

Agree with AEDe

as it is basically Sofirn, why dont take driver construction from C8G? 21700, step+stepless, full stabilization - great driver

I like the choice of LEDs and the UI, I also like the design of the flashlight, I would like to be made in dark gray.

I know that there are flashlights that are regulated, and others that are not. I would be very interested if this flashlight had a good regulation. To give a good example, the Nitecore HC35 is capable of keeping 800 lumens totally stable for almost 4 hours straight with a 5000mah 21700, I would love for this Wukkos to do something similar. If this have a good regulation and a good price, No doubt, i would buy it.

Not sure if the C8G driver is appropriate here. It is designed to drive a 12V XHP35 HI emitter. The first batch I tested had a rather mediocre ramping curve when increasing the brightness. The current applied to the XHP35 HI was about 1.7A only, leaving a lot of potential unused. Moreover, thermal regulation acted way too early on this light. Fortunately, both Wurkkos and Sofirn have agreed to raise the thermal threshold for HD20 to 55°C in return for better performance/longer runtimes on Turbo/High mode. As far as I was told HD20 will be using an FET driver, i.e. no boost driver with full stabilization.

What do you mean

? Linear driver + DD? Linear driver based on FET?

Many of the Sofirn lights + Wurkkos FC11 use a CC linear driver AFAIK.

I would also prefer to pay more and have good regulation.

I’ll take CC linear running on a FET + sense resistor or similar over PWM’ed linear chips any day as long as there is a sub-lumen mode.

Once a cells voltage under load drops below the Vf of your chosen output it will drop anyway. Only a sufficiently low Vf emitter and buck driver, or boost/buck-boost will achieve what I see so many in this community call “regulation”.

If a flashlight has any electronics that control the flow of electricity in at least one mode, it is “regulated”.

Behaviour of fc11 driver
There is no stabilisation at all.
As I understand in Hd20 will be the same ugliness.

the factory engineer said the space of Program is too small so have to use a FET driver, i am not sure :person_facepalming:

I don’t really understand the benefit of defined steps to lower modes when cell voltage drops vs this. Either has the same end result of higher modes losing max output as the cell drains, its why I choose lights with boost drivers whenever possible… because that or multi-cell + buck are the only ways to avoid it.

Well that graph is a bit deceptive:

  1. the drain down to 2.65V is excessive. Most of our firmware triggers LVP at around 3.2 - 3.0V. Looks like this light has no LVP
  2. 3.4V down to 3.0V is a significant drop, > 50%. If you look at a normal drain from 4.2V down to 3.4V, the lumens drops in half. That's about right, and matches what many lights use as "Turbo" to "High". 3.4V to 3.0V is a small percentage of the cell range and happens quickly - refer to discharge curves
  3. lower modes are typically in the 1-500 range anyway, still quite relevant. Also lower modes could be using a low channel having better efficiency that the FET shown in the graph

This graph is typical of most of our FET based drivers running on only the full max FET.

When I turn on 100 lm mode I need 100lm during discharge, and then light should give me know that battery low without turn off.

I see no deceptiveness. I know that in real light will be hint of “stabilization” due to discharge curve of li-ion.
But yes it is classic ugly fet.

This chart does not show that the light will do that before the battery is extremely low. You’d need a runtime chart of that lower mode to see if it drops proportionally over a discharge cycle. In Maukka’s test Vf for 100lm from a 90CRI LH351D is only 2.7V.

Again, the only lights that can sustain brightness like that are those with boost drivers, or multiple cells (with combined voltage exceeding emitter VF) + a buck driver. As soon as the voltage at the emitter drops below the Vf required for a given output, that output will start to decrease. This happens with lights that have an extra 7135 channel for low modes as well since they also cannot step-up voltage.

What are some of the “real lights” that don’t have a drop in output like the graph you posted? What type of alternative driver would you propose for this light?

I think the contentious point is using either linear drivers or FET + sense resistor, vs just PWMing a FET.

The former will probably have constant output (smoother with no PWM, and constant current/lumens), vs just having a fraction of max output (FET-DDed LED crowbarred across the ever-decreasing cell voltage).

It’s switching the light on medium for 600lm across most of the cell’s SOC, vs 800…750…700…650… etc. lm as the cell drains.

Did I mansplain that about right? :laughing:

Oh, good point. I was under the impression that most of the single-cell, 3V emitter Sofirn and Wurkkos lights use CC, not PWM’ed FET so that’s what I’m assuming is planned for this light.