Yes i agree, its a good setup, and so are many others. You can also use the freewheeling / recirculation diode, thats would be a good addition, it has some impact, but i would not expect it to make miracles either. By far (very) the biggest difference should come when you do not pwm the bed, and only use 0%=off and 100%(255)=on, that is full off and full on. The implementation in firmware is different from one to another, sometimes things get strange. For example i know of one firmware if you select bang-bang in configuration, will actually make a sort of bang-bang between 10% pwm and 90% pwm, which is still pwm so its probably even worse than usual pid! So better check how things work in particular, check if you have minimum pwm and maximum pwm values for bang bag, and set them to 0 and 225 instead of any other values in between. Bottom line for heated bed, instead of pid, use bang-bang but double check to have no pwm at all, only constant state output, switching from 0v to 5v and then staying like that untill next change. This way the mosfet will have switching times between 1-2 seconds and more likely approx 5-10 seconds apart, at least mine is like so. Sort of depends on insulation and what value you choose for hysteresis. Mine with mediocre insulation and something like 2 degrees hysteresis is enough to have the mosfet switch very rarely and that means mosfet has really no stress, switching losses per time become neglectable and easily dissipated, and then most losses come from conduction losses only, and thats fine because its how it should be, and losses cant get any lower than that. This operation mode has minimal stress on heated bed mosfet.
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