Fact or just old tale?

[CraigP]

Some folks have heat issues on part throttle because of other issues. When the fetus start to switch fast (carrier freq) the motor coil fly back on each switch cycle. Only the capacitors and batteries can control the amount of voltage that will be made. If you have poor or long wiring, or not enough capacitance to match motor, the ESC will over volt very briefly, like a spike. This happens 8 thousand times a second,per coil! This puts the fetus in avalange mode, essentially breaking down like a zener diode. It causes a lot of heat! It it's hot, get more caps and make sure your connections are rated high enough...

[ray schrauwen]

Darn fetuses.

[Fluid]

Perhaps he meant Festus from Gunsmoke?

Actually he meant FETs, or Field-Effect Transistors.


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[ray schrauwen]

I know, lol. Spell check sucks.

[CraigP]

I hate spell check!!! I say, leave my stuff alone! I look stupid enough without that.....

[CraigP]

Yeah, I really think hot ESC's are more than just the carrier freq kicking in these fets (not fetus) should take that easily. I have applications switching fets at current at 250Khz, so they can take it. It's usually a symptom of hitting avalanche mode. Google "Avalanche mode with FETs" and I think you'll see the common ground to our heat problem.

[CraigP]

BTW, building a new 34 Vortex Hydro and will be running 8S on 4074 1050kV motor. I'm going to build my own cap board that will include different capacitor technologies running in parallel. Each type handles a certain aspect of the switching spike. Also putting in TVS devices... that stands for "Transient Voltage Surge". They flip off (conduct hard) at a given voltage, keeping the ESC at its rated voltage. I'll let you all know how that works out, maybe post with pics and part numbers. If you can solder, you could build one of these...