@doomy if you don’t have any thermal adhesive on hand you can simply mix epoxy and thermal paste. Roughly 50 50 seems to work.
@shaman The field weakening is just my crude implementation. I tried the Axiom PR and it just squealed and didn’t spin? I did copy their field weakening ramp down though as that seemed like a prudent safety feature.
In any case I was able to get 30% extra speed from field weakening with a few hundred watts of extra heat. It seemed to work just as well as on phase shunt hardware but not surprising as the observer is usually fine at high speeds and moderate currents. I got a quick video of it which I’ll upload later.
It probably doesn’t make sense in 4.12 hardware, but for others you should consider providing the option of attaching screw terminals. Like the DieBieMS.
Yeah I’m probably not going make this happen for the cheap FOCer. Maybe for my other designs but I need to see if it has any advantages other than convenience.
Thanks @district9prawn, i used a epoxy and thermal paste mixture like you suggested.
The focers got some real action today, run them with both 7s and 13s BLDC.
Also finished beefing up traces on focer nr4.
A few hints:
Try to get some solder on the other side like in the following picture, the lower part of the mosfet legs is not very thick so this will help getting the current to the upper part of the leg.
Thanks shaman, i know 13s is already over the save limit but most of my batteries are either 13 or 14s. I successfully run the flipsky 4.12 fsesc on 13s for over 1000km now. Hope to do the same with your focers. If a DRV get blown up i just replace it, got some spares and alot of practice now thanks to you.
I just run the board up a steep hill and down again and the even without cooling the mosfets only got up to 50C thats already better than the flipskys. Will do some more tests and post updates here.
Yes i plan to run them on FOC but probably not with a full 13s battery
I just ordered my parts, PCB (10pc’s) + Stencil came out to 28~ due to shipping. then parts sans anything not on the BOM was about 78~ for two (plus a pair of extra DRV’s). so about 53ish per vesc, less you count the per/pcb cost its closer to 41~.
Laborwise, this all seems pretty simple to solder, i grabbed the stencil so i can just paste, place and solder with no fuss, id bet with some practice you’d get a board done in 1-2 hours?
If you order for 5pcs it will be around 25$ per piece.
The first one took me around 3h to build. The other 3 maybe 3h more. Practice makes perfect
I also spent around 10h looking for and resolving minor faults and errors like current/voltage sensing problems, can bus not working, resistors going up in flames and fawlty drv’s mostly due to bad soldering.
The first board took me a few hours and it felt like most of the time was spent matching up a component with its designator. Once I had an assembled board as a reference and some familiarity with the layout it got much faster.
