Since a lot of discussion has been about the case and heat dissipation, I was curious how the efficiency losses added up for this DIY controller vs. the Curtis 1231c I have.
I pulled up the component data sheets and calculated the mosfet losses according to:
Power Supply Engineer's Guide to Calculate Dissipation for MOSFETs in High-Power Supplies - Maxim
You can see the results here:
http://spreadsheets.google.com/ccc?k...KxRc7qBx_aacCw
It also breaks out the losses from mosfet switching, mosfet resistance, and diode voltage drop (all in watts). You can see that the curtis has a very high switching loss! (hence the need to drop the switching frequency to 1.5khz as thermal protection)
In Summary, the DIY controller is calculated to be roughly 4 times more efficient (as in, 4 times less heat dissipation) than the Curtis.
My heatsink runs 15C above ambient with the Curtis when I cruise at 200A. If we assume the heatsink to work just as well with the DIY controller (which, admittedly the curtis has a nice finned Al case to help it), 4 times less heat generation should result in about 4 times less thermal rise, so that puts us at roughly 4C above ambient...
That number might be a bit higher without the finned case, but that's something I can check for once we start testing.