Animalector wrote:Yeah I agree with what you're saying to a point.. But.. Quality control during production plays a part. hobby ebike controllers are cheaply made from cheaply sourced parts. very little quality control. I'll bet a High-end manufacturer will be batch testing their mosfets, miller plateau matching them, blah blah.. whatever they do.. Then, they'll have temperature compensation set 'very' conservatively, they'll have current limiting in place to ensure it will never exceed it's capacity to deliver, and they'll be operating at voltages well within the stated limits for the device. From a design perspective, for an OEM product, replacing the FETs won't be a consideration.
The situations you've described are hobbyists extracting more from their device than what it was designed to deliver.
But I do agree, that TO-220 are easier to replace..
At the end of the day, i'm not going to be seriously stressing this controller (if it ever gets built) so I'm happy to try the SMT fets.
When I swap out mosfets I test all of them and look for the best of them of the stock I have on hand and then collect together the best matched of those mosfets. So called "high end manufacturers" are cutting corners all the time too. Everyone wants to build their stuff for as little effort and cost as possible. Do you get a bit more "bang for the buck" or "better engineering" if you buy supposedly "high end" stuff. I sure hope so! Otherwise, what's the point?
I'm not sure what a "hobby ebike controller" is. Is that the $35 special on ebay? Is that a home built controller? Are ASI FOC controllers or Sabvoton controllers categorically ""hobby ebike" controllers? That's a generic term that can mean anything and nothing.
I have several supposed "high end" controllers. They run motors. Do they do a spectacularly better job than some Chinese controllers I have? No not really....just a little bit better.
On both of the controllers that I have that had bad mosfets in them. One uses legitimate Infineon mosfets and the uses legitimate AOT mosfets. Both controllers were bench testing motors under zero load...just motors free spinning and then the legit infineon and AOT mosfets die? In either controller battery amps were no more than 6 amps which is so ridiculously low that there is no chance EVER that the mosfets were remotely close to an overload situation. Nothing you said about people over watting their controllers had anything to do with what happened to my 2 controllers. Bad components happen. Stuff fails sometimes for no good reason. I don't know what your back ground is, but I've been doing electronic component lever repair since 1988. I've seen lots of supposedly "High end" and well engineered electronic equipment fail for no good reason. Expecting that running components conservatively is not a guarantee that they will not fail. I'm still going to say that easily replaceable components that are more likely to fail is always the best policy.
From a manufacturers perspective, they want to sell stuff they make. They don't care that you can't repair their stuff. In fact they prefer that you can't repair it so that you have to buy another one! From their perspective, SMT components are perfect for them! Also, SMT components are easily machine placable so that saves them manufacturing costs. In anybodies attempt at cutting costs, this is always a good thing for them and bad for people like me. I don't want to throw away an expensive electronic device when I can otherwise repair it. I'll take TO-220 or TO-247 mosfets over SMT mosfets every day of the year for this reason alone. SMT parts make repairs for whatever reason 10X harder to do. Trust me, I KNOW this is a fact! Your logic is flawed in this regard. SMT is good for manufacturers and BAD for you if/when you need to repair something. Does that mean I won't use things that have SMT components on them? No way...that's stupid. But at the same time, if I can avoid it for certain types of parts, well I'm going to avoid it...every time I can. Can SMT power mosfets be reliable? Sure they can, but they also take the brunt of abuse in any controller there is no matter who makes it or how well it is designed.If something is going to fail, it's the mosfets that are going to pop first.
I want to build a Lebowski controller so that I can build the power stage how I want it built. No thank you to SMT mosfets!