In the product description of the VESC 6 MKIV I read:
In its development, no Mosfet switches were used - due to their tendency to eventually blow up. This saves on the additional costs of replacing them, & also adds to the longevity of the VESC 6 MKIV.
I thought "Cool! Maybe they went for IGBTs", however in the schematics I see that the H bridge is composed by six IRF7749 which are... MOSFETs!
I would also like to know if those can be easily replaced with something that can sustain a bit more voltage. I am planning on using a 16S LiFePO4 which tops at 57.6 V at full charge. While 100 A are more than enough for me, I wouldn't mind having a bit more margin on the voltage.
The MOSFETs are not the hard limit on the voltage, the DRV8301 has a maximum voltage of 60V. This is usually what blows up when there is a voltage spike. I'd also recommend not trying to replace/upgrade the IRF4479s as they are DirectFET L8 packages which are very hard to solder correctly.
That entire sentence is complete bullshit and probably should be removed. MOSFETs are switches, so including both words is pointless. They don't have a tendency to blow up unless you drive them wrongly or try and source too much current. The continual use of DirectFETs in official VESC ESCs makes them almost unrepairable. And the VESC 6 mkIV uses MOSFETs anway so it's complete nonsense.
IGBTs only really make sense when you want to run really high voltages >200V.
Eheh, I didn't want to say that but... it stinks pretty badly!
Thank you for the clarification on DRV8301. Do you think that it is safe to use it as it is with a 16S LiFePO4?
2.4V of headroom is not enough. Personally I stick to ~42V for my VESCs but I'm a bit paranoid, 12s/50.5V is pretty popular and about the highest I've seen that doesn't cause problems, so 13s-14s on LiFePO4 cells?
There are 75V VESCs that wouldn't blink at 16s either LiPo or LiFePO4 they may be better suited?
I have found three official models of the VESC: 60/100, 75/300 and 100/250. By no mean I need more than 100 A and as the price of the first is about half the one of the other two, I am reluctant to upgrade.
Are you referring to unofficial/clone models?
As an alternative to the official 3, yes.
I only really have experience with the clones. And while I have a 75/300 I've not used it yet.