Buck and Boost Drivers, Testing, Modding, and Discussion (Pic Heavy)

Can't be that bad, or does it?

No need to feel ashamed or guilty for anything, its our creation so better learn from the experience.

I've taken a look at the video from the ad, looks like its long-necked so long stock focal lenght. Since you changed its lens now it must over-focus, doesn't it?

If the driver is good and the emitter is well heatsinked, it may be a good host after all.

But does it output 50K lumens?

Sure!

Yes stock lens focus right at furthest point from emitter, with alternative lens prime focus is half way instead so a good 50% closer to emitter, but yes will over focus if you move it out to far, in all honesty with a genuine XHP50.2 fitted it puts out a reasonable amount of light

Heatsink is not great , the head is not connected to the body it slides forward/backward on the body so that large heatsink is basically just for show and does not aid cooling, the metal is quite thin even with current reduced to 4A it still heats up pretty fast

Perhaps 2k lumens is more truthful stock figure, the Fake XHP70’s do put out fair power

Just came across these 7A Buck wonder if they are any good?

Also that manta Ray driver is available in Single cell as well

10% - 50% - 100% - strobe - SOS :facepalm: Awful.

Gives me the creeps, and no need to say that ∅32 × 20mm is a lot of space for that kind of performance.

[quote=The_Fat_Controller]

The driver has arrived.
I made a quick test just before feedback the order.

It works well with 3V XHP50.2, although the coil tends to whine softly in high and turbo. To be honest, it was just a really quick test, I used a cheap adjustable buck power supply with quite long wires and crocodile clip connections, and it seemed that better clamping decreases the buzz. So the final installation can be better in terms of noise.

Mmmkay but why 3V XHP50.2? You could drive a (2S) 6V emitter for double the power and higher efficiency.

Because this is an XHP70.2 driver. On 6V output it burns the flashlight. :wink:

Mmm, so you used the 1S/3V emitter hack because you intended to use the driver for long periods on high, isn't it Lacerta?

My 6V XHP50 ≈4A SK98 does good, but its heat path is enhanced and I certainly don't keep it on high for long periods and never out of my hands. On the other hand a triple Sofirn C8F on high with a mid-power 18650 will burn your hand way before its 2m 30s step down if you keep it tail standing. ;-)

I am not a big fan of short lasting turbo levels. :laughing:
Basically the host can handle ~1500 lumens from an XHP50.2 continuously, so the high of this driver with ~1400lm is good, and the turbo is ~2000lm and can be activated separately. This one also have good mode spacing.
Moreover, 6V output buck drivers cannot hold constant current through the whole 2S battery capacity range in high levels, considering the 6V emitter Vf, the battery voltage, and the driver maximum output voltage ( which is ~Vin-0.3V in the best case ).

[quote=Lacerta]

Finally I started to rebuild the host. And also I made some further tests with better wiring.

The first 3 levels are good. Input values are showing constant output values which are corresponding to the specs. With the 3V XH50.2 50mA, 150mA, and 750mA. For 6V led 100mA, 300mA and 1500mA is specified.

But at high and turbo level… The driver seems to get mad. :person_facepalming:
The input current should be around ~1.6 and 2.4A.

But it’s 3.4A at high and 4.5A at turbo! And the inductor is whining like hell. Seems that the regulation is not working properly at higher levels at the increased Vin/Vout ratio. :cry:

I wonder whether the replacement of the inductor would help this? Currently a 4.7uH is installed.

Hello Lacerta,

This thread's been sleeping for a couple months, it would be helpful if you could recap a little bit better what you are trying to diagnose. This is, are you having trouble powering up an 1S emitter (confirmed) with a ∅22 mm Manta Ray buck driver?

You say the driver is pulling (input) ≈3.4 and ≈4.5 A in high and turbo? Could you measure the output figures? That would help to diagnose what is going on. That seems pretty weird but if the thing is really doing its job efficiently the output should be about twice the preceeding input figures (I presume it is being fed with 2S cells).

The inductor may require a swap for better driving 1S/3V emitters (higher inductance). I'm no expert in these matters so wait for some proper connoisseur to chime in.

Hi Barkuti,

Yes, that’s the exact driver.

I did not check the output values since the led base was soldered to the driver. But the led was very bright and dissipated very much heat very quickly.
Another interesting fact. Before this testing, I made another one. The led was also soldered to the driver, and the supply was delivered to the driver through crocodile clips. But the first case the clamping was less firm.
At that case, the input current was ~1.7A in the 4th level and there was no inductor buzz. It is a little high comparing to the expected 1.6A, but still OK. In turbo, the input current was ~3.2A and the inductor had audible whistling.

Previously, I experienced quite similar results when the led was clamped to the driver with crocodile clamps.
For me, it means that any factor which limits the current like wiring / contact resistance helps to eliminate / decrease the inrush.

It seems that the inductor core is saturating and that’s why the PWM controller cannot stabilize the output current. Since the duty cycle is lower than with 6V leds, the peak currents ( caused by higher voltage difference ) should be too high.
And that’s raise a dilemma!
To avoid saturation, a lower inductance needed ( assuming the same inductor size - it’s 1040 actually ). But it also furtherly increases peak currents. To lower peak currents, higher inductance is required. But higher inductance has lower saturation currents.

Of course, using a bigger size inductor is an option, and there’s place to install. The problem is here that there’s a huge selection of cheap 1040s to play with, but not from bigger sizes.

Wellp, as I said before I can't assess the optimization needs for that driver to operate nicely with slightly larger input to output voltage difference, although I can read and pinpoint some interesting tutorial/article like How to Choose the Right Inductor for DC-DC Buck Applications @ Passive Components Blog.

I bought some Murata FDA1254-H-4R7M (half an inch square, 4.7 µH, rated current Isat/Itemp: 11.2/10.2 A) inductors for a crazy mod project more than a year ago, do you think these would do the job any better?

No, I did not expect You to tell the Highest Wisdom. :innocent:
Just talking about modding.

The working theoretics are clear for me, but the calculations are not easy since the major vast of required data is not available.
Though, it is clear that increasing the voltage difference between Vin and Vout reguires higher inductance value for the same ripple.

In the meantime I got remembered that I have some spare inductors in my loot trunk. :sunglasses:
And I’ve found some 4.7uH inductors and also some 10uHs. different sizes, different qualities. Some of them are Coilcrafts.
I removed the original inductor and will test the other ones. :smiley:

Thanks for the tips!

Looking more closely the stock inductor looks about ½" × ½" (more or less like the Murata I mentioned above) so, if its inductance is 4.7 µH, its current specs should be high enough. But of course, very possible it is that whoever is making these drivers may not be purchasing top spec inductors. Just a little bit more inductance should be fine.

You might try the xal7070 series coilcraft inductors. I have used a few and never heard a whine.

Has a low DCR so you should gain a little current without the whine.
The New XGL series looks interesting.

Actually, it’s a 1040 size inductor. On my driver it’s not covered by glue and the 4u7 mark is clearly readable.
The size is not a big constraint, bigger inductors can be easily installed.

I’ve found in 4.7uH some MSS1048 Coilcrafts, some SER1360s and a noname 1080 one. Also have some 10uH SER1360.
I will test whether the inductace value, or the current handling capability is the bottleneck factor.
Thanks for the tips!

Wellp Lacerta, according to what you are saying the stock 10 × 10 × 4 mm inductor in the Manta Ray driver is likely doing its best already, or very close. I mean, were they had chosen a lower specified inductor the driver would have malfunctioned.

The way metal alloy inductors work, their inductance diminishes as they approach their current limits. This basically means a proper quality, higher current rating bigger inductor quite likely will work right even if the Vin to Vout delta is somewhat bigger.

Now that I think of it, the FDA1254s I have lying around will find home in some of these drivers sometime, hope I can raise the current output a nice bit with them. ;-)