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Problem solved yay
Hey guess what? My controller no longer blowing mosfets!!!
Problem source:
Switching ~380 amps is no small task.
Doing it quickly is substantially more difficult.
Even tiny inductances will cause voltage spikes
V = L * di/dt - Vdd
To get a 100V spike (as I must have, to fry the old mosfets)
L = (100 + 12) / (di/dt)
di = 380 amps
dt = 50ns
<I know that's not proper calculus but it gives us an approximate linear slope that in fact should be the best case! i.e. lowest slope>
L = 112 * 50n / 380 = 15nH
One inch of buss bar (or so I have read) at best case is about 10nH. No wonder it fried the mosfets! The voltage spiked over V_(BR)DSS and took it out.
The only thing we can change is dt, the time to switch. I have increased it to 200ns. The theoretical inductance needed to fry my mosfet is now 60nH.
So my starter motor is very happy, spinning away for me, singing me a song. Or so it feels.. This success has been a very long time coming.
I want to thank everyone that helped out in this thread, especially saand for staying with me all the way and giving a lot of sage advice.
Thank you!!!!
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