Understanding EVSE's

Many people do not fully understand the process of how an EVSE (electric vehicle supply equipment) communicates with their Electric Vehicle.

The Tesla UMC, Wall Connector, and Destination chargers are all considered as EVSE's.

First thing to note is that there is no charger in the EVSE and that it just supplies power to the on-board charger in your car.

There are two signals the Tesla and J-1772 protocol uses to communicate between your EVSE and every electric vehicle including Tesla.

Steps in Charging:

1. The charging process begins when you plug the connector from the EVSE into our adapter or your car.

2. The EVSE sends out a signal on the pilot pin that informs the vehicle what the MAXIMUM amount of power is available at the EVSE.  This is to stop the car from pulling to much power and blowing the circuit breaker that feeds power to the EVSE. 

3. Once the car sees this signal and it decides that the available power is above the MINIMUM required by the on board charger it will modify the signal on the pilot pin to inform the EVSE that it wants to activate the contactor (switch) and start feeding power into the onboard charger.


At this time there are only three (3) cars on the market that can pull more than 7.6KW and they are the Rav4, Mercedes, and Tesla. 

So if you have a Wall Connector or Destination charger that is set for 80 AMPS it will never send that much power to the car because the on-board charger will never be able to accept that amount of power.

Even though our Tesla to J-1772 adapters are Rated at 32AMPS at 240VAC (7.68KW) I have personally tested one to 74AMPS at 240VAC (which is the maximum that a 2017 Tesla with the largest charger can pull). The Adapter did not heat up but the J-1772 adapter that comes with every Tesla got a little bit worm.

Personal Note:

I just wanted to help everyone understand that if they have a Tesla Wall Connector that is set to 80 AMPS they do not need to have an adapter that says that it is rated for 80 AMPS. (there will probably never be one). It is just like plugging an 80 AMP Wall Connector into a Tesla Model 3, the EVSE will only supply the power that the car can use.