Is like a small village with roads and buildings 
6 Likes
Nice pics man!
3 Likes
Thanks, I just borrowed this like 10 year old DSLR to try some photogrammetry out!
I tried getting the chip off while fully assembled but all the dang heatsinking makes the ground plane hecka hard to heat from top only.
I just ordered something I needed quite bad, a second hot air gun for dumping heat on DRV chips. This will allow me to blast air at the perfectly bare underside of the ESC directly under the DRV chip. Should work a charm I think. I even got some long curved nozzle for the job!
Makes me wonder if they make little riser blocks you can set on a hotplate to be able to transfer heat to a small surface are like that.
Ok on a second look my CAD model was quite wack
Hmm maybe I could have avoided the second hot air machine…
Or St. Anger for about an hour.
2 Likes
Put solder on the drv sink, don’t roast it.
Drill 10mm hole in table and hold with pliers.
Use a mirror to make sure you don’t knock the iron into the fet, I held the esc solid with blocks.
Time for a quick test I guess.
This clip will help with confidence
4 Likes
I installed an NRF51 module and JST connectors, re-did motor detection and correctly set gearing and wheel diameter.
Took it for a ride and tops out at 55km/h until I get a 20s battery. The motor is a MY1020 style inrunner with 10 poles.
Tried raising battery amps from 70 to 75 and started getting ABS overcurrent again.
Full throttle up a steep hill for ~20 seconds got me up to ~53°C MOSFET temp.
Finally getting logs and a stable connection, just need to force my phone to keep GPS on with a locked screen…
2 Likes
Did you leave the switching frequency up higher than default? If not, try bumping it up to 30 to 35kHZ
Good job! This is thermal management done right
2 Likes
I’ll try 35, but it was still set at 30khz from before. I wonder if the 14awg/2.5mm^2 phase wires have anything to do with it…
3 Likes
The cable size probably doesn’t have anything to do with electrical stability but I would say that 14awg is a bit thin for the power you’re pushing
1 Like
Yeah, it definitely is. I’d like to replace them with 10 or 8 gauge cables and beefier bullet connectors. Same for battery cables. It’s just what the Chinese shipped the motor with and I’m slowly upgrading parts.
I’d also like to mount the thermistor onto the windings directly.
I’ll see what happens when I get a 20s BMS and finish a new battery…
1 Like
So, I’ve started my own build thread
I definitely welcome any feedback on the build.
I’d also like to confirm my plan for mounting the little FOCer to the box body. I’ve searched around but haven’t found much info on how to properly heatsink the mosfets. I know they can short if they touch the heatsink, so I’d rather make sure I’m doing this properly. Apologies if I’m asking about something obvious.
The plan is to use 4mm metal standoffs that are screwed to the bottom of the alu box. Then I’ll use 0.5 mm isolating washers (fishpaper-like material) and I’ve got a 0.5 mm silicone thermal pad, that I’ll put under the mosfets. I’ve measured the spacing on the heatsink that came with the Little FOCer and it’s the same dimensions: 4mm plastic standoffs with 0.5 mm washers and what appears to be 0.5 mm silicone pad. The mosfets should be 4mm.
Is there anything special to be careful about? Anything I should do differently?
3 Likes
The mounting scheme is similar to the CFOC2 and how the guide outlines it. You can also simplify the mounting hardware by using 5mm spacers and 1mm thermal pad. Just use good quality thermal pad.
2 Likes
Hi everyone, I have already ordered everything for diy onewheel except the control unit. I really want a little focer. Do you know when it will be in stock?
First time doing SMD or using a hot air station… getting the chips off went good
Knocked a bit of solder mask off by the DRV with the solder wick but it should be fine.
5 Likes
Cool! Nice job so far. Be sure to let me know once you’re ready to boot up the new STM. There’s some preliminary checks I advise doing to make sure everything is operating as it should be
4 Likes
I did an 11km stress test ride, FINALLY with GNSS data (curse MIUI for making things difficult).
Found out my motor isn’t an MY1020, but a GoldenMotor BLDC-108 10 pole inrunner rated at 48V 1500W, 3000W peak. Basically no info on the internet of people using this motor, not much info from the manufacturer either. I don’t know how much faster I’ll be able to spin it above it’s 5kRPM rated speed without the magnets flying off, kinda bummed. Could use a higher gear ratio without losing top speed.
Top speed is 55km/h. Running 70A battery 120A motor. Raising any of these even by 5A gets me overcurrent. 35kHz switching didn’t help, observer gain is already half of what was detected. I’m not sure how high I can set ABS max, right now at 155A.
When trying to do a burnout, the overcurrent only happens on a grippy surface when the motor just starts to spin with full throttle, right above 2k ERPM. When starting from standstill it seem to vary a little and happens between 3-4k ERPM.
Did 7 full throttle runs up a 15% grade hill. 30m elevation change in 200m, regen braking all the way back down. Started thermal throttling on the 4th run up, decided I didn’t need acceleration temp decrease. Motor case was at 50°C after the 7 runs, so it seems to be handling the power really well.
If by chance the log is of any use to you Shaman, I could send it to you.
Overall, I’m very happy with how it’s all performing.
5 Likes
Great feedback! Yes I’ll take the log file. I’ll also think of maybe some things to try now that we know the actual motor you are using
I sent you a PM.
I might look into replacing either the motor or the whole scooter. Sell it with it’s original controller, make a profit and look around for a new host…
I’m definitely keeping the FOCer though 
1 Like