Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Automatically turn off powerwalls discharging when car starts charging

This site may earn commission on affiliate links.
I have 16KW of solar going to 3 powerwalls (whole system is Tesla), whole house is on powerwalls. 8 months of the year (Southern Cal) we can exist on solar/powerwall and draw no power from grid, aside from charging Tesla at night.

I don't want Powerwalls to discharge when car starts charging at 12:15AM, when Super-OffPeak starts.

Seems like there would be a why to automate this. Currently i run self powered, and set Powerwall to Reserve Percentage the will roughly turn off at midnight. Every night....

Would rather have car charger tell powerwalls to stop discharging, or worse, just turn off powerwall discharge from 12AM-5AM or so.

Am I missing something here, seems like this would not be that hard.

Thanks,
Ben
 
  • Like
Reactions: pilotSteve
I use self powered mode as well, but I dont mind the "extra to the reserve" going to my car in the middle of the night. Is there any particular reason you have not explored using time of use mode, to see if you can get it to do what you want?

 
My car will drain the 30KW remaining in the powerwalls in no time, and i would rather the car uses my cheap SuperOffPeak power, Also discharging the powerwalls to 20% every night seems like a waste. Without charging car, batteries are usually 50-60% charge in the morning when solar starts backup.

I tried TimeOfUse, but powerwalls will stay on and discharge all the time, and that seems like unnecessary wear and tear on Powerwalls.

Doing it the way i have been doing it (adjusting reserve percentage), i had $0 powerbill last year , and built a $1500 credit with power company, so why put wear/tear on the batteries.
 
I would suggest reviewing the thread I linked above, related time of use settings, setting up buy / sell values, etc, and see if that can do the behavior you want.
Roger, i did start reading that, and will digest that. I was think some of these 3rd party smart chargers might have that capability, or potentially the Tesla 3rd gen smart charger, but the "Smart" part is very low on details.
 
Roger, i did start reading that, and will digest that. I was think some of these 3rd party smart chargers might have that capability, or potentially the Tesla 3rd gen smart charger, but the "Smart" part is very low on details.

None of the tesla chargers are smart chargers. They do not provide any scheduling, etc etc. The only integration is to prevent draining the powerwalls if the grid is down, and that is driven by the car, not the charger, and only in a "off grid" situation.
 
I’m still observing how the PW’s behave but so far TBC is working pretty well for me.

My rate plan is 3 tier. Peak 2PM - 9PM weekdays (3PM-7PM weekends) off peak 11PM-7AM weekdays (9PM-3PM weekends) all all other times partial peak. (No partial peak times on weekends. I’ve defined the rate costs to the published rates And set my reserve to 70%.

With the above, on Weekdays, I’m seeing the PowerWalls start powering the house at ~6AM. Solar starts taking over at 8:30AM or 9. Batteries get fully charged by 12 to 1PM. When I get to the peak rate at 2PM, excess solar goes to the grid and PowerWalls power the house until 11PM when I get to the off peak rate. The car is charged at 12AM from the grid at the off peak rate.

On weekends I have only peak and off peak rates. On those days, batteries only power the house during the peak period. So overall I’m pretty happy with that behavior.
 
Last edited:
  • Like
Reactions: jjrandorin
I have 16KW of solar going to 3 powerwalls (whole system is Tesla), whole house is on powerwalls. 8 months of the year (Southern Cal) we can exist on solar/powerwall and draw no power from grid, aside from charging Tesla at night.

I don't want Powerwalls to discharge when car starts charging at 12:15AM, when Super-OffPeak starts.

Seems like there would be a why to automate this. Currently i run self powered, and set Powerwall to Reserve Percentage the will roughly turn off at midnight. Every night....

Would rather have car charger tell powerwalls to stop discharging, or worse, just turn off powerwall discharge from 12AM-5AM or so.

Am I missing something here, seems like this would not be that hard.

Thanks,
Ben
I am doing this using my home automation hub and a bunch of other techno-geek stuff to accomplish it. It does seem like something that should be built into the Tesla app.

In my case I use a Hubitat hub to control my home automation (lights, etc) and it has a third-party app that can communicate with the Tesla API and the Powerwall. I use Teslamate to track the status of my cars, so I know when the cars are charging. Teslamate shares the car status via an MQTT broker. Finally I use an application called Multi-System Reactor which watches the status from Teslamate and sends a command to the Hubitat app to set the reserve battery level to 100% whenever a car is charging at home, and then sets it back to my selected value when the car is done charging. Teslamate, the MQTT broker, and Multi-System Reactor are all running on a Raspberry Pi 4.

I'd be happy to share more details with anyone who has some of the same tech in place and wants to connect the dots.
 
  • Helpful
Reactions: buckets0fun