SAE J1772 overview

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SAE J1772 Overview

I have been interested in public charging and the SAE J1772 standard which will define a standard connector and protocol..

I have been waiting for the new version for about a year with the SAE committee indicating it should be done in a month or two. I was told the changes were minor and the new connector was the main issue. I purchased the 2001 version of J1772 is good and easy to read. SAE J1772 is a copyrighted standard published by SAE International.

I skipped over the DC Charging sections because they don’t seem to relate to charging like I would expect for public or home charging.

After reading it I suspect the main change is the connector and removing extra communication options defined in the 2001 standard.

Typical operation would be:

· Plugs mate.
· +12 is sent out the control pilot pin by the charger.
· The vehicle limits this with a resistor and diode
· The charger starts the +12/-12 signal with the PWM signal indicating usable current.
· When the vehicle charger has set its current limit to that level or less it adds a second resistor changing the control pilot voltage.
The voltage values determine if ventilation is required.
· The charger responds by supplying the power as long as the connection is maintained and ventilation can be complied with.
· The vehicle is to monitor the PWM for changes indicating different current availabilities.
· Removing the resistors or the PWM signal ends the charging.

Level 1 is 115 Volt power from a standard 5P-15 plug 6 to 13 amps.

Level 2 is 208 to 240 volts, hardwired to the power source, 6-32 amps. The PWM spec goes to 48 amps but nothing else does.

There are 3 extra pins in the old connector for serial communications and 2 high power DC charging pins that are no longer in the new one.

It appears that wireless communications, ZigBee, WiFi, or something like On Star will be used to transfer account information if charging is not free or V2G is applied.

SAE J1772:2010(tm) is a trademarked standard of the Society of Automotive Engineers.