Heart Transplant

 If you've followed the evolution of the Porsche EV, you're probably aware of the cooling issues I had with the DMOC 645 inverter. Literally since day one, it would drastically limit current whenever the ambient temperature was over 90 degrees F, which is most of the summer and fall here in Austin. Winter and spring the car ran great, summer it was undriveable, moving away from stop lights at a snail's pace. I complained about it in my test drive video. Clip ends at around 12:02.

I've revamped the cooling system and added capacity on several occasions without success, and decided that if the car was to be a year round driver some drastic steps would be needed. After Jack Rickard passed away, I was randomly watching old EVTV videos and ran across one from 2014 where he was planning to test a brand new Scott Drive SD100 with a Siemens motor like mine, replacing the DMOC Inverter and GEVCU controller. Clip ends around 1:31:13.

Tagged and ready to ship from EVTV

After a little research on the Scott Drive, it looked like a nice replacement for my dodgy DMOC. It was developed and manufactured in New Zealand but EV parts dealers in the US didn't carry it. Guessing that the shipping on a new one from half a world away would be prohibitive, I got in touch with Richard Flentge of EVTV to see if the one from the video might be available. Sure enough, it turned up in the shop and after the exchange of a couple DC/DC Converters and some $$$, it was on my workbench in October, 2020. 

Scott Drive on my workbench

I got the old DMOC and GEVCU removed and started working on the physical mounting for the new controller. 5/8" marine plywood will give a solid but slightly compliant platform with room for terminal blocks. Paint it black and it will disappear. I also took the opportunity to remove a bunch of old wiring and generally tidy up the under hood area. I'm quite pleased with the result.

The Scott Drive is a handsome piece of technology and looks like it was custom painted to match my motor bay. Part of the beauty is the integrated precharge circuit and contactor much like the Soliton1 controller in my MG TD. With integrated control electronics both the GEVCU and precharge modules are eliminated which makes for a much cleaner installation. Next we'll set the configuration, and that's a whole new adventure continued in the next post ...