Put EV charger on backup gateway?

[dpowell]

I'm in the process of installing (20) REC panels, Tesla Powerwall 3, and Tesla backup gateway. Because the Powerwall 3 has much better throughput than the Powerwall 2 I was planning on leaving all of my circuits, including my EV charger, on the backup gateway so I could still charge my car during a power outage. My concern is whether or not this would add too many power cycles to the battery during non outage times. Would normal daytime EV charging go through the battery or does the system pull directly from the panels and charge the car without involving the battery? If not maybe I should leave the EV charger out of the backup gateway and only be able to charge during non outage times?
Any advice is appreciated!

 

[smoked_g60]

I'm in the process of installing (20) REC panels, Tesla Powerwall 3, and Tesla backup gateway. Because the Powerwall 3 has much better throughput than the Powerwall 2 I was planning on leaving all of my circuits, including my EV charger, on the backup gateway so I could still charge my car during a power outage. My concern is whether or not this would add too many power cycles to the battery during non outage times. Would normal daytime EV charging go through the battery or does the system pull directly from the panels and charge the car without involving the battery? If not maybe I should leave the EV charger out of the backup gateway and only be able to charge during non outage times?
Any advice is appreciated!

Tesla recommends putting your charger on the backup circuit. If it is a Tesla it will have the ability to stop charging automatically if there is an outage, or also to change from solar as a priority if you are charging your EV during the day.

If you don't want to cycle your battery as much, set the reserve higher on the app.

 

[dpowell]

Tesla recommends putting your charger on the backup circuit. If it is a Tesla it will have the ability to stop charging automatically if there is an outage, or also to change from solar as a priority if you are charging your EV during the day.

If you don't want to cycle your battery as much, set the reserve higher on the app.

So if I have the charger on the backup circuit it will be drawing through the battery even during non outage times, correct? If so, that seems like a lot of battery cycling. Not sure what the benefit would be to have it on the backup circuit if I was going to tell the car to stop charging during outages anyway...

 

[smoked_g60]

So if I have the charger on the backup circuit it will be drawing through the battery even during non outage times, correct? If so, that seems like a lot of battery cycling. Not sure what the benefit would be to have it on the backup circuit if I was going to tell the car to stop charging during outages anyway...

Depends on your settings in the app. If you set the battery to discharge to 10% then it will use 90% of the battery to offset loads including your car charger.

If you set it for 90% reserve, then it will use 10% of the ESS for the same needs.

The benefit is that in an outage, you can use your vehicle battery as a second ESS, when you have a great sunny day and your main ESS is full you start charging the car instead of just wasting the solar with curtailment.

 

[dpowell]

Depends on your settings in the app. If you set the battery to discharge to 10% then it will use 90% of the battery to offset loads including your car charger.

If you set it for 90% reserve, then it will use 10% of the ESS for the same needs.

The benefit is that in an outage, you can use your vehicle battery as a second ESS, when you have a great sunny day and your main ESS is full you start charging the car instead of just wasting the solar with curtailment.

Great explanation. Thanks!

 

[chrisski]

For me, as long as your gateway can handle the 11 kW of charging at 48 amps plus what ever else the gateway may power, seems like a solid plan.

Tesla does things a little different than my Outback Radian. For my System, I'd rather sped the battery power on running the Air Conditioner in the summer at 3 X the off peak rates. For my car, I'm happy to wait a couple of hours after I get home and start the charging at the cheaper off peak rates.