Help with driver modification for higher current draw

Flashlight Modding and DIY Parts
1

Hey guys,
I have this driver (22mm Output 6v Led Driver Circuit Board Für Xhp70/70.2 Leds 2/3 3.7v Li-ion Battery Powered (input 5.6-12.8v) - Buy 6v Driver Board,6v Circuit Board,Xhp70 Driver Product on Alibaba.com) which is rated for 4.8A. I recently upgraded the batteries in the light where I have this driver and they are now capable of delivering 10A continuous. Do you know of a way to upgrade this driver for higher current draw? Or would you just suggest to get a different driver instead? The LED is a XHP70 6V so it should be able to handle the higher current without issue afaik.

Thanks for your help

2

Does anybody maybe have a schematic for the driver? This would be a lot of help

3

Might be a low-value sense resistor which senses current. Halve that resistance, and get twice the current, etc.

I wouldn’t push it too hard, though, because if it uses an inductor, that might saturate and just burn up heat vs delivering current. Also, FETs might be pushed too hard and go pop. Etc.

It’s like boring out an engine. You might get more horsies for a while, but then other things not meant to handle the extra, just go snap at random times.

4

The only visible resistor is 1Ohm which is to high for a sense resistor afaik.
Maybe I will just look for a different driver

5

There’s a sense resistor next to the LED- wire, but we can’t read the value on the product pictures, can you take pictures ?
but beyond changing the sense resistor it depends on what the buck converter is capable, everything is mostly covered by the inductor so it’s difficult to say.

6

I made a mistake, I misread r010 for 1 Ohm, not for 0.01Ohm.

So this seems to be the sense resistor. I will try a smaller resistor and see what it gets me.

7

I’ve a similar driver and might be interested in a similar mod, keep us updated :grinning:

8

First I need a small enough resistor. The smallest one I have at home is 1.8 Ohms. Adding this in parallel wont make a difference.

9

Just for confirmation, I swapped the resistor with a 1.8Ohm one. This results in a current of about 29mA so I can confirm that this is the sense pin. At this current, the battery life should be amazing. The light output however, is not.

10

…upgrade wires , remove RPP fet (maybe), overcome spring.

11

What does RPP stand for?
there are 2 Mosfets on the board as far as I can tell. One on the backside and one below the inductor. Both have the same inscription: 7409 bv7g1h
I guess this means this one https://aosmd.com/sites/default/files/res/data_sheets/AON7409.pdf.

12

And which wire size would you recommend?

13

Use thick copper core as possible

14

Its rated for 4.8A. Do you think it can handle 6.4 before it blows up?
For that I would add a 0.03Ohm resistor in parallel

15

The resistors arrived today. I have added 2 0.03Ohm resistors on top of the 0.01Ohm resistor. This should give me a total of 8A. The light is noticably brighter and I dont think I should push the driver further. I cant measure 8A but I think that this is because of my multimeter having too much internal resistance.

16

Get a clampmeter that does DC, like the venerable Uni-T.

You’ll thank me later.

17

Thanks I will look into that. I have been thinking of changing the emitter as well. I looked at the XHP70.2 and it looks like a decent upgrade because of the lower voltage. How does the XHP70.3 compare the the XHP70.2? Havent found much data on that.

Is there another emitter you would recommend here?

18

MT-G2, but people would laff at my “antiquated” choice.

Dunno if it’d handle that kinda power through it, though.