I’m contemplating tweaking my Q8 with XHP35 HI.
I’d like something that can sustain as many candelas and as many lumens as possible, so I need efficiency.
I don’t have the skills for such mod yet, but it doesn’t stop me from seeking options.
2s~~12V boost with XHP35 seems like a natural choice. Or even 4s>24V. Buck 4s12V could work as well, just like boost 1s~~>12V.
Is there anything that would work well in such setting?
I guess BLF GT, but it won’t give good current to 4 LEDs, will it?
Something else?
The BLF GT driver in stock form would be able to drive them at around 1.25A each, maybe a bit higher. If you upgraded some components it could do around 2A each.
Not great, but not bad either. Turbo won’t be as high as possible, but 8A is significantly above what Q8 can sustain anyway. Will fall out of regulation before batteries are half emptied. And efficiency should be good, right?
1.25A on stock GT driver with 500kHz frequency possible
I am working on an upgraded GT driver
I am discussing with del the needed changes
So far Buck frequency changed from 800 to 500kHz
input and output caps doubled, the design already has pads to fit 2 caps instead one
Diode 3A to 5A
inductor from 6A to 15.5A
6-8A should be no problem to get to
10A might be possible but that’s about the current the XHP35 get not much gain over 2A anyways
Yep, with those changes it should handle 8A. The issue then becomes it falling out of regulation very quickly due to the voltage drop with only 4 cells.
You could get fully regulated 50W output using LTC3119 buck boost with 4S input and 12V output. Around 4.2A output is my guess. Bonus is that lower output power can also be used with 1S or 2S input.
Using 2S input the MP3431 chip could probably give you 8A output fully regulated. I don’t know of any existing boards for either IC though.
If you want to design a PCB there will be some design considerations for heat, especially for the MP3431. Realistically we can assume around 90% efficiency, maybe a bit better, but at 100W+ of output power that is still going to be almost 10W of heat into the driver. Most of this will be between the IC and the inductor. So you will need to design a PCB using the full available driver size, and ensure that the IC has a good heat path to the host through the PCB. Remote mounting the inductor directly to the host with thermal adhesive would also help, and it frees up PCB space as a bonus.
This is a very powerful one, not cheap at all, but we target 8A for 6V LEDs, XHP35 can be as hard driven as desired
I got the board made in Diptrace I made improvements
power cap pad sizes increases to a 0805/1206 dual footprint, depending if 1206 fit to the driver cavity
other parts 0402/0603 Footprint
MCU/LDO caps 0805 size to use OTSM cap
and especially the thermal connection of the boost Chip got improved massive using the inner layers with direct thermal path through viases
No place for programming visases so a solder pads or pogo pin connector plate
ignore the 2. ring around it its just for production on a bigger board for easier separation
Really neat work with the implantation !
That big square is the coil I presume ?
I know it’s early stage development but do you have a guess at how how much it could cost once assembled/programmed for a lambda Customer like me ?
Also a Narsil variant will be coming as well, just needs further testing of a low standby current precision OP Amp
The bare material costs on this driver alone will be about 14$ From Mouser
Lets say about 6$ for assembly, customer support and testing
For first 50 drivers likely about 3$ to cover development
Shipping will be more expensive than TA drivers as its more than 10mm thick packed 4.5$
Its a small powerhouse, but the regulator can pull up to 19A from the battery, which gives an impressive output on 6 and 12V
For Narsil drivers above about 35mm the GT layout is likely the cheaper variant with same output and better efficiency on this the components are almost as cheap as regular multi cell FET+N+1 AMC based drivers
That’s really impressive, it means 50W output would be relatively easy right down to 3V, which in turns means 4000+ OTF lumens whatever the battery level on a single 18650 with the right led configuration.
That’s better than any production light I know of if it ends up being produced I’ll definitely have to get one.
I am so excited about Schoki’s Boost driver I can hardly contain myself.
I have actually been collecting parts and am now starting to look for hosts for this driver. These will be the first real lights I have built in almost a year, there was just nothing to significantly upgrade from what I had before.
Now I have plans to rebuild most of my collection around these drivers. The XHP35 is better then the XP-L or L2 in every way, more lumens, more throw, no tint shift. Then you have the xhp50.2 and xhp70.2 for some big flooder fun.
I have almost talked Schoki into letting me beta test some of these drivers…