Right... Finished the 2nd PWM mod today. The first one was a bit of a mess, holes drilled in the wrong place, window for display cut too big etc... It is working well however and I'm using it every day at the moment.
The parts are:
Big Al's 4S sled mount board
standard pot and 12mm flush switch
Fat Daddy's V4 510 connector
I've used the mod meter to have a bit more info. It shows watts, bat voltage, output voltage, current and coil resistance. Unfortunately it doesn't seem to show correct values. Values are changing when fired. I expected problems measuring the output voltage because of the PWM.
It is a well working mod but it is definitely a prototype kinda thingy. The box is messed up pretty bad, a few scratches, holes in the wrong spot. One of the magnets got in the wrong way so i had to push it in further and put another one on top. Of course the lid won't close completely now. I will probably take that mod meter out again (or better take the sled, board, 510, pot and switch into a nicer box) so I haven't tried to hide the wires/mess on the inside. It's the 2nd blue mod on the pic. The black ones are a Cuboid and a Cuboid mini to compare the size.
Here's the inside. What can i say, electrically sound but ugly.
Today I've finished the 2nd PWM mod. It is the first one of the 4 on the picture. Different parts, it is a Murata OKL2-T/20 module on a base board for easier wiring. Should be good for around 100W Relatively easy to build, a few smd components and battery clips on board instead of a battery sled.
Unfortunately the enclosure is just a little bit too small so i had to trim the sides of the battery clips off to fit he batteries. With the clips i can only fit one battery. I consider this experiment failed because to make this board fit properly you have to use a bigger enclosure. But in a bigger enclosure it wastes space because without the board and just the OKL2 you could then fit a 3S battery sled.
I will still keep it for a while before i use the enclosure for something else. It vapes well but has a few imperfections. I've epoxied the wrong color display into the box. It's a red one which i got mixed up with the blue one. Not a problem, just a bit annoying.
Next problem is that I must have used a wrong pin on the pot. Power is inverted, full at 0% and none at 100%. Also the hole for the pot wasn't quite perfect so the pot has a little gap.
The box is good, it closes perfectly and i was able to hide the scratch i made under the bezel.
Thanks to @Whiterose0818 i was able to finish populating the last board I've bought to find out which kind of technology i want to use for future PWM builds. It was a bare PCB for a PWM driver with a digital pod so it has up/down buttons for the voltage and can be locked etc. The board has been tested and is ready to go into a mod. But there are already problems with this board and I'm pretty sure i won't be buying it again.
The board is just too long. I could fit it in a wider box behind the 510 connector but in a box wide enough for this board i can fit 3x18650 and for 3S this board is not good enough. You can only use maybe 1.5mm² wire which is good for maybe 100watts.
Mounting it on the side gives you enough space for the voltmeter and the board but you have to use the on-board fire button. There's not enough space for a bigger fire button.
So.... learned a lot the last couple of days. I think for future builds i will use more Big Al's boards. There's a sled mounted "intelligent" one now which looks very promising and there are rumors it will be available in the UK soon. I've also learned that i should spend more time cleaning devices before i take pictures. I underestimated the camera. And i will have to buy stainless steel versions of the tanks from now on, the black ones look stupid on the blue boxes.
Wow... long post... thanks again to @Whiterose0818 for valuable advise, I'll definitely keep going and the next steps will involve resin and stabilized wood.