LTLFTcomposite wrote:AndyH wrote:Too many guess without facts, gents! ...
We think we know that the "emergency" 120v cord plugs into the J1772 connector. But do we know if it actually does pilot signaling or does the car just have some default behavior when 120 volts appears on the pins unannounced? (eg start suckling at 12 amps) And if so, what is there a similar behavior in Europe, but at 240volts?
Per the J1772 spec, any EVSE MUST provide a pilot signal. The spec is clear about what the EVSE sends to the car and how the car responds. It's back in post 2 - but posted again here.
This from June 19th...
I have a copy of the J1772 recommended practice from Jan 2010. I haven't yet played with any hardware designed to use this standard, so cannot say how EVSE manufacturers are actually using the info in the J1772 doc.
According to the document, the Control Pilot signal performs multiple functions. It allows the EVSE to properly detect that a vehicle is connected. The EV receives a signal that the EVSE is ready to supply energy. The EVSE is notified if the charge area needs ventilation. Finally, the EVSE signals the EV, by modulating the pilot duty cycle, to communicate the maximum available continuous current capacity.
22.214.171.124 IF the EV/PHEV reads a duty cycle of 3-7%, the EV/PHEV shall interpret this as a valid digital communications command.
126.96.36.199 IF the EV/PHEV reads a duty cycle between 8% and less than 10%, the EV/PHEV should interpret this as a valid 10% duty cycle.
188.8.131.52 IF the EV reads a duty cycle less than or equal to 85.0% the EV/PHEV should base the current on the Amps = (% duty cycle) * 0.6 formula.
184.108.40.206 If the EV reads a duty cycle greater than 85.0%, the EV/PHEV should base the current on the Amps = (% duty cycle - 64) * 2.5 formula.
220.127.116.11 IF the EV reads a duty cycle of 97%, it is recommended the EV/PHEV consider this as a valid 96% duty cycle.
Bottom line - if the car is in compliance with the CURRENT J1772, it cannot charge without a pilot signal of some type. Either the car will receive a pilot signal between 10 and 97% to set the proper current limit, or it will receive a 5% pilot signal and know to listen for more instructions on the digital data signal (not the same as the pilot signal) (and not yet defined as that's in another SAE standard).
Note again the lines on table 6B for signals below 3%, between 7 and 8%, and over 97% - Error state , no charging allowed. No pilot = error state and charging cannot start.
We could guess that Nissan has found a way to be J1772 Jan 2010 compliant while allowing a straight extension cord connection for a 120V emergency charge. If they did that, and since they're supplying the 120V EVSE, and since they would have a larger profit if they could provide a 'dumbed-down' EVSE product, why would they include a full EVSE in the trunk bag rather than a $5 extension cord with a J1772 connector?
Then there's the down-side risk of shock (no EVSE means that the hypothetical hacked emergency cord would have live terminals when it's connected to 120V - illegal for J1772) and legal action from the 'unsafe' connection when clearly 'safe' products are available and in full compliance with J1772. I really don't think they'd take that risk.
edit...typo...$5 vice %5