I think the pictures are from different Sevcons EDIT: it should be: a different Sevcon. I used 150V FETs since he wrote that it has a 350A 2 min limit, which matches the controller with a 116V max battery voltage, which should use 150V FETs.
http://www.sevcon.com/media/2104/gen4_data_sheet.pdf
Now that I take a second look, I think that they are maybe 100V FETs, since the allowed nominal voltage is 80V.
With IRFB4110, you can divide every number in the previous calc by two. It's still roughly on par with the SMD version.
EDIT: After looking at it a third time, I'm back to thinking it is 150V FETs. Sevcon could never specify 116V max voltage if they are using 100V FETs. 80V nominal battery on 150V FETs, thats a good margin.
http://www.sevcon.com/media/2104/gen4_data_sheet.pdf
Now that I take a second look, I think that they are maybe 100V FETs, since the allowed nominal voltage is 80V.
With IRFB4110, you can divide every number in the previous calc by two. It's still roughly on par with the SMD version.
EDIT: After looking at it a third time, I'm back to thinking it is 150V FETs. Sevcon could never specify 116V max voltage if they are using 100V FETs. 80V nominal battery on 150V FETs, thats a good margin.