Quote:
Originally Posted by BrianG
In another post somewhere, I do mention that the HS would most likely ablate (although I used a less fancy word  ) if it does happen to touch. I'm glad that these things are tested so vigorously, but shorting phases on purpose can't be good!
And I understand your point about the HS having more resistance than the coils, but the HS does not have any back-EMF that coils do. So, does that rule still apply?
Also, if a motor has X ohms of resistance, and the HS has X*2 ohms of resistance, then the two (effectively in parallel during a potential short) has X*0.66 ohms of resistance (until the Al ablates). To me, that's just pushing it for no reason. Even if the FETs don't mind this, this can't be good for the batteries.
As far as people modding things based on advice from these forums, I can take partial blame I guess. But, that was for previous versions and I did provide disclaimers (more than once). The only mod I have suggested to a V3 is to place a thin piece of lexan between the bullets and the HS, which of course needs no disassembly or soldering, and provides a little piece of mind (to me anyway). Believe me, I don't claim (not even close) to know as much about this stuff as a true engineer such as yourself, I just get a little apprehensive when I see things I don't feel is right. |
Hey Brian,
Well, in the experiments we did here, the heat sink ablates so fast it doesn't even warm the FETs much. (short term surge currents of 1200A don't hurt the FETs or batteries, but it sure vaporizes some aluminum pretty quickly!)
