Has anyone modded a H1-A boost driver?

I recently built a p60 dropin with the Kaidomain H1-A boost driver (What did you mod today? - #2814 by vinte77) and I wanted to see if anyone had any mods that they’ve done to the driver. The driver has 5 modes: LL-L-M-H and double click for strobe. Additionally, here’s a several things I’ve noticed about the driver : 1) there’s a pre-flash when you go to the lowest mode, LL; 2) there is next mode memory; and 3) on my build a tail light switch does not affect the driver modes (without adding a bleeder resistor). The output on the driver is good, I got around a 5 amp reading on 22 awg wires and no wire bypass on the driver spring.

Main issue for me is the Next Mode Memory, I would like it if there was a way to bypass NMM and always start on low.

Couple pics




Should be one of the capacitors (brown thingies) for Next Mode Memory, but which one?
The big resistor (black thingies with numbers on ’em) should be the current sense resistor (lower for more output), and the big capacitor and inductor (big gray thing) should be the main power circuit.
The big IC (black thing with multiple connections) under the inductor is probably the microcontroller, and the 3 connection IC on the bottom is probably a FET for the switching circuit.

Also have people tried this with 12V leds? From the looks of it this is a basic boost driver so it should work but with half the output.

Unfortunately, I don’t have a spare driver on hand to test out any ideas on. Plus, I’m not sure I have the skills to figure out which capacitor it is that controls NMM.

You may want to try asking BanL, he's Kaidomain's representative (and flashaholic) around here.

Don't forget to ask how the @#$% do they dare to implement such a PoS in an expensive product geared for aware people who clearly dislike that sheesh. It's an awful joke.

I just PM’ed him. Hopefully, he has some insights into the driver that he can share with us.

You could try the pencil trick on each one.

But if I do the wrong one will it change anything else on the driver?

I guess I am lucky the H1-A driver I got also does have the pre-flash when you switch to low mode, but it has on-time memory with a ~3 seconds set time. I would rather have off-time memory but on-time is better than next mode memory

@ doubleone44 : I will test the driver with a XHP35 when I get home it didn’t even cross my mind that it could work.


Just tried a XHP35 didn’t work I measured 7,22 V @ the emitter.

Or it could be that the driver I got that has an issue. I have more on the way that I can test once I get them in a month or so.

So I got confirmation from Ben that the driver has 3 second on-time memory as khas has said. I think I might’ve done something to my driver where the on-time memory got disabled. I asked Ben if he could point out the resistor that affects driver memory, so I’ll report back when I get a response.

Kaidomain has a 12 volt version of this driver. It’s rated at 1.5 amp at the emitter. The H2-C.

RS. FREAK at TLF (in German) made a resistor mod and measured lumens (but not current) on an XHP50. Using measured XHP50 power curves and a stock current of 3A for the H1-A it can be calculated that adding 1xR100 gave him about 3.55A and 2xR100 about 4.2A. Driver gets pretty hot.

Determining the current sense resistor stack value for a given current is no rocket science. It can be clearly seen in the photographs the driver uses an onboard R025 sense resistor. Thus:

V = I × R = 3A × 25mΩ = 75mV sense voltage

It can now be clearly seen how each R100 set in parallel adds 0.75A to the total driving current. Of course, excluding losses.

In conductance terminology: 0.025Ω is 40Ʊ (siemens, A/V), so when 75mV drop on a 40Ʊ pathway (resistor), 3A of current flow through it. For the same reasons, when 75mV drop on a 10Ʊ pathway, 0.75A of current flow through it. A 10Ʊ pathway is 100mΩ.

This conductance stuff is interesting for certain applications, because:

G = G1 + G2 + … + Gn (R = 1/G)

1/R = 1/R1 + 1/R2 + … + 1/Rn (G = 1/R)

G is conductance, unit siemens, symbol S or Ʊ.



So any idea how to fix the next mode memory?

It doesn’t have that. Never did.

Ah cool, read the other posts properly.
So it’s on time memory.

Mine doesn’t have next mode memory

Yes, Banl said so in a post about these drivers and I also got a email from Kaidomain stating it as well. User Khas has an H1-A and reported the same. Mine should be arriving soon.

It has on-time memory. Meaning you have to leave it on a level for 3 seconds and it will be memorized. If you turn the light off before 3 seconds it will register that as a half press and then turn back on in the next mode.

I believe this is a driver Kaidomain is making themselves. They created the firmware themselves and its kind of a basic design. Hopefully they will figure out how to put off time memory in it. They also said they can do custom levels if 25 or more are ordered.

Thanks I missed that earlier, definitely an option now.