- It charges at 16A instead of 10, so as fast as my on-board charger will allow
- It's lighter and smaller than the stock portable EVSE, most importantly: it now fits in the glove box!
- It's got a rubber instead of PVC cable, so much less stiff and more durable, while also being slightly smaller in diameter
- It's got thicker conductor wires (3x2.5mm2/13AWG instead of 3x1.5mm2/15AWG)
- It's just a cable with a mains plug on one end and J1772 on the other, no big 'box' in the cable
- I have full control over the design, i.e. I can change stuff if I want (and I will)
I did this by designing a custom controller board that fits inside an Aliexpress-sourced Duosida SAE J1772 plug. It was a proper struggle to get it all in. Nonetheless this was successful, and I've used the cable for three full charges of my range-extended 2011 Leaf, meaning it's been hanging on in freezing temperatures and ice rain for at least 24 hours. I call that a win.
The cable is NOT SAE J1772 COMPLIANT. Let me just be up-front and clear about this. It will fail any sniff test, as the mains plug is more than 30cm from the EVSE control electronics. As I find this stipulation in the rules stupid, I ignored it. Otherwise, it complies with the entire charging standard; it has a GFI safety feature, it switches both live and neutral, the relays are rated over industrial temperature range for the full current, the EVSE electronics are galvanically isolated and the EVSE will latch off on car and EVSE errors. As the connector is not IP-rated, the electronics are conformally coated inside. I should probably pot the electronics.
I don't consider this a 'good' design yet. As you can tell from the video, fitting the board in is fine, but fitting the cables in as well is a struggle. I'm also bypassing the strain relief bracket with a generous amount of hot glue. Lastly, I have already overloaded somebody's home fuses once, as pulling 16A on a single phase maxes out our standard circuits here, and using any big consumer on that group will quickly trip a fuse. So, in a future version, I would probably want to:
- Make the electronics even smaller
- Make dedicated routing paths with fastening points for the high power cabling
- Give it a switch between 10 and 16A
- Put the LED on top, probably dual-color, bit brighter
- pot the entire thing inside
I don't think this is viable as a commercial project. I already had to spend about €100 to make this one, which means that if I were to include workmanship and sell the thing, it'd basically be the same price as any other portable EVSE, but then very low volume and made by some schmuck on the internet who barely gives warranty. I wouldn't trust me with that. Nevertheless, if there is enough interest to warrant the time investment, I might try to do a revision and make a couple boards for people to tinker with. Not sure how many people still use granny chargers.
Also: I realize that this is a bit Eurocentric; this lead really only has any right to exist on 208/240V.