Moving EV Circuit from Backed Up to Non-Backed Up

[gpez]

Hi gpez,

Yes, it would be nice to be able to charge at home when I really need it. But, things are starting to sound pretty expensive to move things around. I appreciate all the suggestions.

Thanks,

GHTech

Sorry, still not following...

I thought that you already have your WattStation on a Powerwall backed up circuit, you were worried that during a power outage at night that if your EV was charging it would drain the Powerwall and you wanted to prevent that by moving the WattStation on to a non-backed up circuit. If you're not really charging the EV at home I'm not sure what the problem is...

Hi h2ofun,

With the EV on the backed up circuit, if there is a power outage, the EV could wipe out the batteries to charge the car. No way to have the car stop charging if there is a power outage.

Regards,

GHTech

Since moving the circuit is expensive could you maybe summarize your situation and what you're looking to accomplish? Do you want to ensure that the EV charging won't drain your Powerwall on accident while also still being able to charge it from solar/Powerwall during an outage?

 

[GHTech]

Sorry, still not following...

I thought that you already have your WattStation on a Powerwall backed up circuit, you were worried that during a power outage at night that if your EV was charging it would drain the Powerwall and you wanted to prevent that by moving the WattStation on to a non-backed up circuit. If you're not really charging the EV at home I'm not sure what the problem is...



Since moving the circuit is expensive could you maybe summarize your situation and what you're looking to accomplish? Do you want to ensure that the EV charging won't drain your Powerwall on accident while also still being able to charge it from solar/Powerwall during an outage?

Hi gpez,

Ideally, I would like to move the EV charger (Level 2) to the non-backed up panel, so that in case there is a power outage the battery would not be drained. At the moment, I get free charging at work, so I do most of my charging at work. That could change at any time. If there is a prolonged outage, I can always run the Level 1 charger to charge the car off the Powerwalls. We have a van to do any running if needed, so not totally depended on the EV. The other reason that I want to move the EV to the non-backed up panel is that I would like to convert some of the appliances in the house that are currently on natural gas to electric, and put it on the backed up panel. Not having the EV circuit will help with that goal.

Regards,

GHTech

 

[gpez]

Hi gpez,

Ideally, I would like to move the EV charger (Level 2) to the non-backed up panel, so that in case there is a power outage the battery would not be drained. At the moment, I get free charging at work, so I do most of my charging at work. That could change at any time. If there is a prolonged outage, I can always run the Level 1 charger to charge the car off the Powerwalls. We have a van to do any running if needed, so not totally depended on the EV. The other reason that I want to move the EV to the non-backed up panel is that I would like to convert some of the appliances in the house that are currently on natural gas to electric, and put it on the backed up panel. Not having the EV circuit will help with that goal.

Regards,

GHTech

Super helpful, thanks!

Moving the L2 charger to a non backed up panel is one, but not the only, way of preventing the Powerwall from getting drained during an outage and moving circuits is a pretty expensive prospect for such a narrow goal so that's where my confusion was coming from.

Now changing the appliances adds more complexity and you're likely right that you'd have to shed some load from the backed up circuits if you want to add more high wattage appliances to the backed up panel. To that end, what @wwhitney said sounds correct that you (and your electrician) would have to do all of the calculations to determine what circuit would need to go to what panel. May end up that moving the L2 charger is the only option but then you correctly identified the workaround during an outage to use a L1 (which is exactly what I do).

 

[miimura]

I am wondering if the new PCS feature in the Gateway 2 would allow more loads on the backup side of the Gateway while retaining the 100A feeder from the main panel to the Gateway. The idea of the PCS feature is that the Gateway will command the Powerwalls to discharge to keep from overloading the feeder.

 

[GHTech]

Greetings,

I wanted to give a quick update. I have the 2 issues/needs/concerns listed below:

- @wwhitney noticed that the 100 amp breaker that feeds the Gateway was installed in a spot that supports up to 70 amps.

- My EV Charger is currently on the backed up panel. Wanted to move it to the non-backed up panel so that while charging the car, if there is a power outage, the car would not drain the Powerwalls. Please note this is not Tesla car. @aesculus also brought up the issue that I would need CT's to monitor the EV charger circuit.

I contacted Tesla about both these issues. They came out today to take care of both. I was expecting to have to pay for the EV charger circuit move, but did not have to. The Tesla electrician moved the 100 amp breaker to the correct location, and moved the EV charger circuit to the non-backed up panel and added the CT's. After this was done, the report of the usage in the app was pretty messed up. My 8.16 kW system that is currently generating a peak of about 6.8 kWh, was showing that it was generating 16 kWh. He had to get Tech Support involved, and after about 2 hours of working on it, was able to fix the reporting.

One issue that I noticed is that even though the EV charger circuit is on the non-backed up panel now, it pulls power from solar and Powerwalls. I assumed that only the grid would be used. I guess I was wrong. I am told that it is normal to charge from the solar and Powerwalls (until the Reserve is reached) while the grid is up. If the grid is down, then this EV circuit is going to be down.

Regards,

GHTech

 

[miimura]

Greetings,

I wanted to give a quick update. I have the 2 issues/needs/concerns listed below:

- @wwhitney noticed that the 100 amp breaker that feeds the Gateway was installed in a spot that supports up to 70 amps.

- My EV Charger is currently on the backed up panel. Wanted to move it to the non-backed up panel so that while charging the car, if there is a power outage, the car would not drain the Powerwalls. Please note this is not Tesla car. @aesculus also brought up the issue that I would need CT's to monitor the EV charger circuit.

I contacted Tesla about both these issues. They came out today to take care of both. I was expecting to have to pay for the EV charger circuit move, but did not have to. The Tesla electrician moved the 100 amp breaker to the correct location, and moved the EV charger circuit to the non-backed up panel and added the CT's. After this was done, the report of the usage in the app was pretty messed up. My 8.16 kW system that is currently generating a peak of about 6.8 kWh, was showing that it was generating 16 kWh. He had to get Tech Support involved, and after about 2 hours of working on it, was able to fix the reporting.

One issue that I noticed is that even though the EV charger circuit is on the non-backed up panel now, it pulls power from solar and Powerwalls. I assumed that only the grid would be used. I guess I was wrong. I am told that it is normal to charge from the solar and Powerwalls (until the Reserve is reached) while the grid is up. If the grid is down, then this EV circuit is going to be down.

Regards,

GHTech

If the CTs are placed correctly, the Powerwalls will see the EV circuit and its usage. If you don't want it to use battery power to satisfy that demand, use Time Based Control and use the EV charger during Off-Peak times.