A Haikelite HK90S driver with some photos (and some questions that I have!)

Flashlight Modding and DIY Parts
1

A month or so ago I ordered a Haikelite HK90S with the intent of modding it, since it could handle bigger (9090) LED’s and has a FET driver so in theory it should be able to push a powerfull LED quite hard.

Today I removed the driver, mainly because I wanted to replace the very thin (22AWG) wires that Haikelite used, but after I was finally able to remove the driver (it was ‘glued’ in place), I noticed a couple of things that raised some questions (for me).

So I decided to take photos of the driver and to dedicate a topic to it.

First of all a general overview of the driver:

1000012211
10000122111920×2122 727 KB

A ‘close up’ of the charging SoC IC:

1000012212
10000122121920×2080 730 KB

But here is the part/section of the driver that raises a few questions to, given my lack of (enough) knowledge:

1000012213
10000122131530×2040 321 KB

1000012214
10000122141963×2013 462 KB

As you can see in the photos above, it uses an Infineon (real/fake?) BSC010NE2LS MOSFET, but to the left of it there is an unoccupied pad, which, as far as I can tell, could also house a Mosfet.

My question now is: Would it be worth it (and would it work) if I place a second MOSFET there, given that the whole purpose of this flashlight is to mod it and put a more powerfull LED in it?
(I would probably swap out the current FET and install 2 brand new, matching ones.)

That brings me to my second question:

As you can see in the photo below (and probably already noticed in the photos above), Haikelite did some really “Creative Soldering” on the driver, next to the MOSFET(s):

1000012216
10000122161487×1432 423 KB

What is the specific purpose/goal of this horrible and ugly solder blob?

The R18 and R17 markings above it, indicate to me that it originally was intended for 2 resistors, but I assume the bridged the pads by use of that solder blob.

Does it relate to the unoccupied/unused MOSFET pad/slot?
(In that case I assume that, if it is worth placing a second FET, I have to remove the solder bridge and place the correct resistors on R17 and R18.)

So to recap: Is it worth/will it work, placing a second MOSFET on that unused slot and secondly: what is the specific purpose of that ‘solder blob’ and/or is it related to that second MOSFET slot?

2

Blob: where the current-sense resistor would be.

FET parking space: possible, but you might possibly get always-firefly mode from leakage, and you’re chancing the gate drive to get halved.

Unless you’re okay with reworking it multiple times as trial and error, I’d just leave it stock. Cook the glue too much, and you risk lifting the traces off the board.

1 Thank
3

I constantly monitored (inside and outside of the head) and it never exceeded 70 ℃ (max. I measured was 68 I believe). I was fully aware not to heat it too much due to the risks to the driver. It turned out it was more something like a (flexible) sealant and just above 60 ℃ it became just flexible enough I could push out the driver out and break the connection.

It had to come out anyway, because the 22AWG driver wires are (almost) certainly too limiting for the LED I’m planning on putting in the light.
Modding this light was the sole reason I ordered it, so I knew there could always be risks or setbacks when disassembling the light.

Hadn’t thought of that, thanks!

Fair points and viable (possible) reasons not to put in a second FET.

It’s not my favorite activity, reopening/reworking the same light several times and repeating work that I’ve already done.

I wasn’t planning replacing or adding FETs in this light, but when I unexpectedly stumbled on that open space, I started thinking about it, since I had the light disassembled anyway.

For now I will leave it stock and first check out how the original plans for this light turn out. I could always go back in anyway.

I constantly monitored (inside and outside of the head) and it never exceeded 70 ℃ (max. I measured was 68 I believe). I was fully aware not to heat it too much due to the risks to the driver. It turned out it was more something like a (flexible) sealant and just above 60 ℃ it became just flexible enough I could push out the driver out and break the connection.

It had to come out anyway, because the 22AWG driver wires are (almost) certainly too limiting for the LED I’m planning on putting in the light.
Modding this light was the sole reason I ordered it, so I knew there could always be risks or setbacks when disassembling the light.

4

I meant soldering multiple times, not in operation.

1 Thank