TEG said:
GaslessInSeattle said:
ok, my bad, so how does the stock Tesla EVSE deal with all the variation given all the adapers/outlest, without any signal coming from a charging station?...
Their EVSE creates a pilot signal and sends it to the car.
It creates a different pilot signal depending on which plug end you attach to the cable.
(It has an extra circuit to let the EVSE know what kind of plug you are using.)
It has no idea what sort of breaker or wiring is behind the socket, but makes assumptions about what wattage should be available from different types of sockets.
No, this isn't correct. The EVSE has NO IDEA what plug you may have on the end of it (it appears Tesla did not follow the J1772 exactly, and may actually be able to do this), nor is there a protocol to provide that information in J1772. A stock Tesla Model S or Roadster can select how many amps the car will draw from the dash of the car. If you were plugged into a 240 volt air conditioner at a motel with a 20 amp plug and breaker, and the EVSE were the standard 40 amp unit that comes with a Model S, and the Model S were set to over 20 amps, it likely won't work too well (either popped breaker or overheated wires and possible fire).
From Chris Howell's basics of the J1772:
http://code.google.com/p/open-evse/wiki/J1772Basics" onclick="window.open(this.href);return false;
Pilot
The J1772 Pilot is a 1khz +12V to -12V square wave, the voltage defines the state and the duty cycle defines the current available to the EV. The EVSE sets the duty cycle and the EV adds resistance from the pilot the Ground to vary the voltage. The EVSE reads the voltage and changes state accordingly.
State -- Pilot Voltage High - Pilot Voltage Low - EV Resistance - Description ----- PWM
State A ---- +12v ------------ N/A --------- N/A ---- Not Connected --- DC
State B ---- +9v ------------ (-12v) ------- 2.74k ---- Connected ----- 1000 Hz
State C ---- +6v ------------ (-12v) -------- 882 ----- Charging ------ 1000 Hz
State D ---- +3v ------------ (-12v) -------- 246 - Ventilation Required - 1000 Hz
State E ------ 0 -------------- 0 ----------- N/A ----- No power ------- N/A
State F ----- N/A ----------- (-12v) --------- N/A ---- EVSE Error ------- DC
Max Current
Up to 51A Amps = Duty cycle x 0.6 Duty cycle = Amps / 0.6
51 - 80A Amps = (Duty Cycle - 64) 2.5
Duty - Max
Cycle - Current
< 3% -- (Error)
3% ---- 7% (Digitial Com Required)
10% --- 6A
20% --- 12A
30% --- 18A
40% --- 24A
50% --- 30A
60% --- 36A
70% --- 42A
80% --- 48A
86% --- 55A
88% --- 60A
90% --- 65A
92% --- 70A
94% --- 75A
96% --- 80A
>96% - (Error)
Proximity Signal
This is a simple check of either 150 ohms (connected) or 150 + 330 ohms (button pushed to disconnect)
