Heinz wrote:First of all, a big thank you to everyone who has contributed to this project. It's a remarkable piece of engineering, electrically and mechanically.
Even though I'm not an expert in high power electronics I have a background in tube guitar amp building. So I had a look at the EMW charger schematics. The power stage uses some serial/stacked capacitors in order to increase the maximum voltage. This is common practice in tube amps, as well. However, it seems advisable to add balancing resistors so the two caps share the voltage equally. Without balancing resistors the center voltage is not guaranteed to be at half the total voltage and may drift due to age, temperature and tolerances. Eventually, one of the caps may experience a voltage in excess of its rating which will destroy it. Two 100k 1/2W resistors in parallel to the caps should do the trick.
The discussion about the QC connector pins and materials also caught my attention. I did some research on IEC 60309 plugs which are rated up to 125A. These are somewhat similar in construction and contact design. The pin material on these industry standard plugs is brass up to 32A and nickel (or nickel coated brass) for 63A and 125A. However, I was unable to find out the exact plug and pin diameters. I have some 16A plugs at home and the pin diameters are 5mm for the phases and 7mm for the neutral. Since there are so many different types of these plugs I'm wondering if there is one that has 9mm pins. These may be a good starting point for a DIY chademo connector. I will go to a hardware store and take measurements.
Thanks Heinz for your kind words and for your suggestions. You are absolutely correct regarding balancing resistors. This will have to be done in the next revision of the boards.
Regarding pins - after a reasonably long search, we now can finally make complete plugs with pins and all. We have found a local 3D print shop that is not charging an arm and a leg for large prints and who was willing to work with us through 3+ iterations of the build parameters to avoid warping, account for shrinkage, etc, etc. We have also found a precision machine shop that could build the pins to our exact specs. Finally, we found a precision plating shop that could nickel & silver-plate our pins to the same spec as Nissan parts (yes, we measured the silver thickness with precision instruments). large 9mm pins are pure 110 copper with 1 mil silver plate, small signal pins are brass with 0.5 mil nickel plate.
Pins pic attached. You can now buy the plugs from our store with just 2-week lead time.
You do not have the required permissions to view the files attached to this post.