shaman wrote: ↑
Apr 22 2019 5:31pm
ElectricGod wrote: ↑
Apr 22 2019 5:14pm
AKA good components hold up to over watting and abuse better than cheap parts.
There are still some "gotchas" behind this. Yes reputable semiconductor companies often derate their devices to ensure reliability over full temp range or other environment conditions. Yes you may be able to exceed Vmax by X volts at 25C ambient but that may not be the case at 100C. You also may very well decrease the life span of the device by exceeding it's max parameters.
However we can often get away with exceeding the max parameters of devices for short durations. It's you're call as an engineer/DIYer/user on how much you want to push that limit.
If by "short duration's" you mean years...such as in CREE LED's, then I agree. A typical real CREE LED is rated for something like 10 years of life. Admittedly I don't have 10 years on any LED I over watt, but I definitely have been over watting them for more than 1 year and that with regular use for an hour straight or more. When I over watt an LED, I run it continuously for an hour straight before I consider it reliable. What's more, I'm pushing the XHP70.2 to 7v and 9 amps, not 8v and 15 amps like I've seen documented with good reliability.
I'm not trying to be argumentative here, but my suspicion is that this is also true for good mosfets and that they will hold up to a bit of over voltage situations just fine. Heat is the biggest semi-conductor killer so don't let them get too hot. Of course pushing parts well beyond their limits is likely to be catastrophic..like my 36v mosfet at 48v showed. It never had a chance to get hot as it failed immediately. These comments are not in any way an attempt to say "Let's run at well over specs all the time", but rather "It can be done to some extent and be done reliably." Legit CREE LED's are proof of this.
I know lots of people that "just use ready made controllers" and have no idea what the parts inside do. For those folks, just stay within specs. For people like me that regularly get 5-6kw and more out of 12 fet controllers, well this isn't really a big concern. I'll happily push my controllers and "risk" the possibility of a blown mosfet. At 82v and 6kw is 73 battery amps. At 66v and 6kw is 90 battery amps. Phase amps is obviously MUCH higher and I usually have that set to 130...or peaks of nearly 11kw in the phases of a 12 fet controller. So far...several controllers later...no blown mosfets...as long as the controller does not get too warm.