SAE J1772

The SAE J1772-2009 was adopted by electric vehicle manufacturers in the Chevrolet Volt and the Nissan Leaf. The connector became standard equipment in the U.S. market due to the availability of charging stations supporting it in the nation's electric vehicle network (helped by funding such as the ChargePoint America program drawing grants from the American Recovery and Reinvestment Act).[13][14]

The European versions were equipped with a SAE J1772-2009 inlet as well until the automotive industry settled on the IEC Type 2 “Mennekes” connector as the standard inlet – since all IEC connectors use the same SAE J1772 signaling protocol the car manufacturers are selling cars with either a SAE J1772-2009 inlet or an IEC Type 2 inlet depending on the regional market. There are also (passive) adapters available that can convert J1772-2009 to IEC Type 2 and vice versa. The only difference is that most European versions have an on-board charger that can take advantage of three-phase electric power with higher voltage and current limits even for the same basic electric vehicle model (such as the Chevrolet Volt/Opel Ampera).

CCS Combo 1 vehicle inlet showing the J1772 and the two DC fast-charging pins

In 2011, SAE developed a J1772/CCS Combo Coupler variant of the J1772-2009 connector in order to also support the Combined Charging System standard for direct current (DC) fast charging, which includes the standard 5-pin J1772 connector along with an additional two larger pins to support fast DC charging. Combo 1 accommodates charging at 200–920 volts DC and up to 350 kW. The combination coupler will also use power-line communication technology to communicate between the vehicle, off-board charger, and smart grid.[15] Seven car makers (Audi, BMW, Daimler, Ford, General Motors, Hyundai, Porsche, Volvo, and Volkswagen) agreed in late 2011 to introduce the Combined Charging System in mid-2012.[16] The first vehicles using the SAE Combo plug were the BMW i3 released in late 2013, and the Chevrolet Spark EV released in 2014.[17]

In Europe, the combo coupler is based on the Type 2 (VDE) AC charging connector (Combo 2) maintaining full compatibility with the SAE specification for DC charging and the HomePlug Green PHY PLC protocol.[18] In 2019 Tesla introduced the Model 3 with a CCS Combo 2 plug in Europe, but has not introduced models with CCS in the US. With the introduction of the Model 3 in Europe, Tesla added CCS charging cables to V2 Superchargers (supporting both CCS Combo 2 and Tesla DC Type 2). European V3 Tesla Superchargers include only a CCS charging cable.

The J1772-2009 connector is designed for single phase alternating current electrical systems with 120 V or 240 V such as those used in North America and Japan. The round 43-millimetre (1.7 in) diameter connector is keyed and has five pins:[19]

SAE J1772 / IEC 62196-2-1 Type 1

	Row	Position	Function	Notes
	Top[lower-alpha 1]	1	L1	"AC Line 1"
		2	N	"AC Neutral" for 120 V Level 1 charging or "AC Line 2" for 208–240 V Level 2 charging
	Bottom[lower-alpha 2]	3	PE	"Protective Earth" aka Ground
	Middle[lower-alpha 3]	4	PP	"Proximity Pilot" aka "plug present", which provides a signal to the vehicle's control system so it can prevent movement while connected to the electric vehicle supply equipment (EVSE; i.e., the charging station), and signals the latch release button to the vehicle.
		5	CP	"Control Pilot" is a communication line used to negotiate charging level between the car and the EVSE, and it can be manipulated by the vehicle to initiate charging and can carry other information.[20] The signal is a 1 kHz square wave at ±12 volts generated by the EVSE to detect the presence of the vehicle, communicate the maximum allowable charging current, and control charging begin/end.[21]

The connector is designed to withstand 10,000 mating cycles (a connection and a disconnection) and exposure to the elements. With 1 mating cycle per day, the connector's lifespan should exceed 27 years.[22]

• 
  Black release button on an SAE J1772 plug in a mockup car
• 
  SAE J1772 plugs operated by thumb at a Vietnamese charger
• 
  Adaptor cable from Nissan with Type 1 plug for the car, Type 2 plug for a European charger socket
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  IEC 62196 Type 2 connector with openings on the side for automatic release

The SAE J1772 or Type 1 plug is locked into the car with a hook that is manually operated, mostly by pressing a button with the thumb, which interrupts power. This allows anybody to stop charging and even theft of the cable. To prevent this, the European IEC 62196 Type 2 connector has openings on the side for automatic locking and release, operated by the car owner via remote control. If the car locks or releases its plug, the charger will follow suit according to the PP signal.

The SAE J1772-2017 standard defines four levels of charging: AC Level 1, AC Level 2, DC Level 1, and DC Level 2.[23] Earlier released revisions of J1772 also listed a never-implemented AC Level 3, which was considered but never implemented.

For example, the 2020 Chevrolet Bolt has a 66-kWh lithium-ion battery and a 7.2-kW onboard charging module; with an EPA range of 259 miles (417 km) and energy efficiency of 118 mpg‑e (29 kW⋅h/100 mi; 17.7 kW⋅h/100 km),[25] it can use its portable charge cord to charge at AC Level 1 (120 V, 12 A) to get up to 4 mi (6.4 km) of range per hour or go off an AC Level 2 charging unit (240 V, 32 A) to get up to 25 mi (40 km) of range per hour. Using an optional DC fast charging (DCFC) port, this model can also charge at up to 55 kW to get up to 90 mi (140 km) of range per half hour.

Some EVs have extended J1772 to allow AC Level 1 (120 V) charging at greater than 16 amps. This is useful, for example, at RV parks where TT-30 ("Travel Trailer" - 120 V, 30 A) receptacles are common. These allow charging at up to 24 amps. However, this level of 120 V charging has not been codified into J1772.

Another extension, supported by the North American Charging Standard, is Level 2 charging at 277 V. Like 208 V, 277 V is commonly found in North American commercial three-phase circuits.

The J1772 standard includes several levels of shock protection, ensuring the safety of charging even in wet conditions. Physically, the connection pins are isolated on the interior of the connector when mated, ensuring no physical access to those pins. When not mated, J1772 connectors have no power at the pins;[26] they are not energized until commanded by the vehicle.[27]

The proximity detection pin is connected to a switch in the connector release button. Pressing the release button causes the vehicle to stop drawing current. As the connector is removed, the shorter control pilot pin disconnects first, causing the EVSE to drop power to the plug. This also ensures that the power pins will not be disconnected under load, causing arcs and shortening their life. The ground pin is longer than the other pins, so it breaks last.

Control Pilot (Mode): The charging station sends a 1 kHz square wave on the control pilot that is connected back to the protective earth on the vehicle side by means of a resistor and a diode (voltage range ±12.0±0.4 V). The live wires of public charging stations are always dead if the CP–PE (Protective Earth) circuit is open, although the standard allows a charging current as in Mode 1 (maximum 16 A). If the circuit is closed, the charging station can also verify that the protective earth is functional. The vehicle can request a certain charging function by setting the resistance between the CP and PE pins; 2.7 kΩ announces a Mode 3 compatible vehicle (vehicle detected) which does not require charging. 880 Ω says the vehicle is ready to be charged, and 240 Ω requests with ventilation charging, in which case the charging stations supplies charging power only if the area is ventilated (i.e., outdoors).

The Control Pilot line circuitry examples in SAE J1772:2001 show that the current loop CP–PE is connected permanently on the vehicle side via a 2.74 kΩ resistor, making for a voltage drop from +12 V to +9 V when a cable is hooked up to the charging station, which activates the wave generator. The charging is activated by the vehicle by adding parallel 1.3 kΩ resistor resulting in a voltage drop to +6 V or by adding a parallel 270 Ω resistor for a required ventilation resulting in a voltage drop to +3 V. Hence the charging station can react by only checking the voltage range present on the CP–PE loop.[28] Note that the diode will only make for a voltage drop in the positive range; any negative voltage on the CP–PE loop is blocked by D1 in the vehicle, any significant current that does flow in the CP–PE loop during the negative period will shut off the current as being considered a fatal error (like touching the pins).

For IEC62196-2 male plugs the Control Pilot pin is made shorter to prevent untethered cables being used as "extension leads", This prevents the use of downstream cables that may have a lower current capability being connected to a cable of a higher current rating.

Control Pilot (Current limit): The charging station can use the wave signal to describe the maximum current that is available via the charging station with the help of pulse-width modulation: a 16% PWM is a 10 A maximum, a 25% PWM is a 16 A maximum, a 50% PWM is a 32 A maximum and a 90% PWM flags a fast charge option.[29]

The PWM duty cycle of the 1 kHz CP signal indicates the maximum allowed mains current. According to the SAE it includes socket outlet, cable and vehicle inlet. In the US, the definition of the ampacity (ampere capacity, or current capacity) is split for continuous and short term operation.[29] The SAE defines the ampacity value to be derived by a formula based on the 1 ms full cycle (of the 1 kHz signal) with the maximum continuous ampere rating being 0.6 A per 10 µs up to 850 µs (with the lowest 100 µs × 0.6 A = 6 A). Above 850 µs, the formula requires subtraction of 640 µs and multiplying the difference by 2.5. For example (960 µs − 640 µs) × 2.5 A = 80 A.[28]

The proximity pin, PP (also known as plug present), as shown in the SAE J1772 example pinout, describes the switch, S3, as being mechanically linked to the connector latch release actuator. During charging, the EVSE side connects the PP–PE loop via S3 and a 150 Ω R6; when opening the release actuator a 330 Ω R7 is added in the PP–PE loop on the EVSE side which gives a voltage shift on the line to allow the electric vehicle to initiate a controlled shut off prior to actual disconnection of the charge power pins. However, many low-power adapter cables do not offer that locking actuator state detection on the PP pin.

Under IEC 62196 the Proximity Pin is also used to indicate the cable capacity – this is relevant for non-tethered EVSEs.

The resistor is coded to the maximum current capability of the cable assembly. The EV interrupts the current supply if the current capability of the cable is exceeded as detected by the measurement of the Rc (shown as R5 in the J1772 signaling circuit above), as defined by the values for the recommended interpretation range.

Rc is placed between the PP and PE, within the detachable cable assembly.

[30]

In an updated standard due in 2012, SAE proposes to use power line communication, specifically IEEE 1901, between the vehicle, off-board charging station, and the smart grid, without requiring an additional pin; SAE and the IEEE Standards Association are sharing their draft standards related to the smart grid and vehicle electrification.[31]

P1901 communication is compatible with other 802.x standards via the IEEE 1905 standard, allowing arbitrary IP-based communications with the vehicle, meter or distributor, and the building where chargers are located. P1905 includes wireless communications. In at least one implementation, communication between the off-board DC EVSE and PEV occurs on the pilot wire of the SAE J1772 connector via HomePlug Green PHY power line communication (PLC).[32][33][34]