M0 went up in smoke

Hello there

I am slowly getting crazy…

After I had trouble with my first board, I finally decided to get a new one and try to repare it when I have more time, the knowlege and the possibility to smt solder.

So I ordered a new board. After wiring, I finally plugged the battery in. First i did the usual beginner Tutorial to check if all worked. I noticed that the board was not running on the newest firmware. So I used pos.setpoint instead of input_pos. Not a big deal at all.

After that, I wantet to flash the current firmware. As the python dfu tool did not work again. I tried to do it manually.
I forced the Odrive in Dfu mode. But some time after I plugged the battery in, I noticed a white smoke comming out of M0. I immediately unplugged the battery. The motor did not heat up or anything.

I am using a Odrive 3.6 24V

With two 3s Lipos serial (23.54 V)

I am so frustrated. What may have caused this?
I guess, for now it means the end of my project until I get some money =(

Were you flashing during this, or was it only in DFU mode? Before it failed, were you able to connect on USB? How long would you say the battery was plugged in before the smoke escaped?

I was not flashing, it was not in DFU, I was able to connect to USB, About 2-3min

I googled “4C05N” from your picture of the exploded MOSFET and came up with this: https://uk.farnell.com/on-semiconductor/ntmfs4c05nt1g/n-channel-mosfet-30v-dfn-5/dp/2473411?st=NTMFS4C05N
This part has an “absolute maximum” instantaneous voltage of 30V, with a breakdown (ie guaranteed smoke) at 34V.

I suspected the reason that the 24V version is cheaper, is because it uses 30V FETs.
23.54V is way too close to the 24V limit for my liking.
Is it possible that the battery was charged to slightly more than 24V at the point when you plugged it in? In which case, that could have damaged the board by inrush.

When you first plug in a board, unless you use anti-spark connectors which have an internal resistor, the charge propagates like a wave across the board - even though you have a 24V battery, you could see slightly more than 30V (possibly 34V!) momentarily at the end of the board when you first plug it in, due to the inductance of the wiring and PCB traces - especially if you have heavy, high-current wiring between the battery and PCB, and especially if it is long and not twisted.

For this reason, I think the 24V board is no good except for 12V applications - maybe 16V - but certainly not 24V.
If you have a 24V battery, you should use the 56V board. The names are very misleading, and I think they need to either change them or discontinue the 24V version.

See: Overvoltage error with "24V" Lithium Ion batteries

Yes this is correct, though with normal wire lengths to the battery, meaning not too much inductance, it is unlikely to cause permanent damage. This is because the MOSFETs have an avalanche breakdown energy rating.

@Matthew I see you also had another board die. I would very much like to see if we can figure out why boards keep dying for you. To start with I want to send you a new board. Can you please send me a DM on our discord with your order number? I am “Oskar” on there. We can keep chatting there also and maybe find a time to dig deeper into this?