There is a standardized system using passive components in the cord that allows the charging station to determine the capacity of your cable.
The IEC 61851 standard for the Mennekes socket used in Europe:
1.5k = 13a
680k = 20a
220k = 32a
100k = 63a
It's also possible to buy 80A EVSE cable
here, made in USA, although it probably won't be for sale much longer. ITT-Cannon has a 75A J1772 coupler with 75A cable, and a couple of other sources have couplers rated at 70A to use with a cable like that linked above.
ITT has discontinued that 75 amp J1772 assembly (I have one of them on my Clipper Creek CS-100 series EVSE). That eBay cable is PERFECT, since it has the needed proximity conductor that few cables have.
As to the "other sources", I presume you mean the Dostar J1772 plug that I put on the Tesla UMC's. That was recently downgraded to 50 amps after being presented for UL approval.
So, to date, there has not been a single 80 amps J1772 plug ever offered to the public that I'm aware of. The 70 and 75 amp versions have disappeared.
I have to confess if I was doing this I would be very tempted to build a 30A cable like you did. I can't imagine using it anywhere that has more than 30A.
The same basic due diligence that we would each use with any extension cord would apply.
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Assuming the 14-50 extension cord is rated for 50A max and 40A continuous current, it shouldn't be a problem. For instance, a Tesla UMC with 14-50 adapter will never pull more than 40A.
Except a Tesla UMC isn't the only EVSE in the world. I can put a 14-50 on any J1772 with a simple, commonly available adaptor.
If I do that on one of the 70 amp, J1772 equipped Tesla/Roadster Clipper Creek EVSEs, there could be a problem!!!
We're getting a long way from the issues with the J1772 extension, however.
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... The key is what you know. You could get out of a claim against you because Bechtenshire, UK passed a law saying that J1772 extension cords must use yellow wiring only - who would expect you to know that? You assume some risk when you know that your cord is technically illegal for consumers to use in 99%+ of the US and you don't disclose that fact.
I'm actually not going to play lawyer on the internet, or pontificate publically how somebody can manipulate the legal system to their advantage. You'll note that I don't criticize somebody who might produce an adaptor for electric vehicle charging, even though that is specifically "illegal" in most of Europe.
So, again, what I know has nothing to do with what I'm offering, and that offer is specifically "as-as" and "with all faults" and "no warranty for merchantability". Heck, somebody may use if for a noose and commit suicide with it, yet I offer no warranty that it might do that job without injury, death, etc.
This will be the final rebuke of the legal ramifications.
... they'll use that illegal part every time to deny coverage. Not a shot against anyone's technical expertise.
This is a common, and often quoted quip, but you'll find that it's actually not the case many times. It's dangerous in a debate to use EVERY TIME, because invariably, somebody will find the exception(s) that make your statement wrong.
What don't we put some positive energy into developing a safety circuit?
I need a circuit designed that will limit the maximum EVSE pilot signal "duty cycle / pulse wave modulation" to the following:
1) EVSE pilot signal > than XX duty cycle, output XX pulse wave modulation (PWM) only
2) EVSE pilot signal <= to XX duty cycle, let the EVSE's PWM pass through unchanged
This device would be placed between the EVSE plug pilot signal pin and the car's pilot signal pin. That signal is a 1kHz 12/-12 volt square wave with the following duty cycle:
10% - 96% = 6 amps - 80 amps
>96% = Error
One simple option might be:
XX% duty cycle = 96%, but then is wouldn't work with duty cycles greater than XX%
I want to be able to limit to XX%, not stop above XX%.