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Powerwall charging Tesla's during outage
- Thread starter Shygar
- Start date
RoBoRaT
PoPeYeD'SaiLoRDuDe
Yay! We tweeted Elon asking for this feature last year and he said it was coming. Glad to see it. Looks like we need our Powerwall firmware updated and will only support our Model Y currently but we can definitely use this feature. It was in the 70s on Saturday but we've gotten over 16" of snow since Sunday and our Powerwalls charged from the grid last night thanks to Storm Watch.
As a native southern californian, I could not even imagine "snow in april". We had a lot of rain where I live in april (a couple straight weeks of it, which is almost unheard of, lol), but it was 79 degrees at my house yesterday, and mid 70s and sun today... its beautiful outside right now, soft breeze, etc.
Wow. Talk about changing weather. Rained at my house of the weekend and went down to mid 50s. Up to 70 today. That is a a big change for us.
I’m also interested to see how this will work. Sentry mode does this well pretty now since I tell it to not come on while it’s in the garage at home so I imagine it will be something similar as opposed to requiring a HPWC for this to work.
reddy
Active Member
Thanks for sharing this.
I'd like to coordinate even while ON-GRID. I'm not in a net metering area, so I get only about 1.5c/kWh for excess production. (Not a typo, that's WHY I have Powerwalls!)
So I would like to be able to charge the Powerwalls to 90% first, then have the car charge at the same rate of excess solar production until the car is charged maintaining the Powerall at 90%, then have any remaining excess go to the Powerwall to top it off.
Given that my power outages are once in a blue moon, and THIS I could use almost every day, that would be a feature that would get used.
The Tesla app must be able to alter the charge rate, which is a feature we have been suggesting for years.
It would also be great to allow us to change the charge rate from the app, in order to coordinate with the solar production and minimize grid usage.
I'd like to coordinate even while ON-GRID. I'm not in a net metering area, so I get only about 1.5c/kWh for excess production. (Not a typo, that's WHY I have Powerwalls!)
So I would like to be able to charge the Powerwalls to 90% first, then have the car charge at the same rate of excess solar production until the car is charged maintaining the Powerall at 90%, then have any remaining excess go to the Powerwall to top it off.
Given that my power outages are once in a blue moon, and THIS I could use almost every day, that would be a feature that would get used.
The Tesla app must be able to alter the charge rate, which is a feature we have been suggesting for years.
It would also be great to allow us to change the charge rate from the app, in order to coordinate with the solar production and minimize grid usage.
We have 4 PowerWalls and Tesla vehicles (S 100D, X100D).
When we installed the solar panels and PowerWalls, we left the two HPWCs connected directly to the grid - and use them for normal charging.
We also added a 14-50 outlet to one of the breaker panels powered by the solar panels/PowerWalls, that we would use if we had an extended power outage (after a hurricane).
So we'd only want charging to be impacted when we were using the 14-50 outlet - not when the vehicles are connected to the HPWCs.
When we installed the solar panels and PowerWalls, we left the two HPWCs connected directly to the grid - and use them for normal charging.
We also added a 14-50 outlet to one of the breaker panels powered by the solar panels/PowerWalls, that we would use if we had an extended power outage (after a hurricane).
So we'd only want charging to be impacted when we were using the 14-50 outlet - not when the vehicles are connected to the HPWCs.
My TEG is still on old firmware so I do not have any experience with this new feature.
Will this feature work on a TEG NEMA 14-50 circuit?
It seems to me that the car could determine fairly easily that it is plugged into a non-Wall Connector TEG circuit: Attempt a brief charge and check the TEG API for delta instantaneous draw or the TEG could temporarily alter the AC frequency a bit for the car to notice.
It would be a shame if Tesla designed this feature to have the car set the “charge current” instead of the mothership. Being able to remotely, through the mothership API, set charge current has other uses, including being able to match instantaneous solar production to avoid the PW roundtrip. Has anyone seen an API command for setting “charge current”?
Will this feature work on a TEG NEMA 14-50 circuit?
It seems to me that the car could determine fairly easily that it is plugged into a non-Wall Connector TEG circuit: Attempt a brief charge and check the TEG API for delta instantaneous draw or the TEG could temporarily alter the AC frequency a bit for the car to notice.
It would be a shame if Tesla designed this feature to have the car set the “charge current” instead of the mothership. Being able to remotely, through the mothership API, set charge current has other uses, including being able to match instantaneous solar production to avoid the PW roundtrip. Has anyone seen an API command for setting “charge current”?
It may be a security consideration that they aren't exposing this to the mobile app. The only API I know of is the one for the mobile app, and the last version I looked at does not have a way of setting the charge current. Given the way they're rolling out support to different car models at different times, I'm guessing it is going to be the car controlling the current. This does imply that it should work just fine using the mobile adapter (or potentially even non-Tesla EVSE).
“Security”
Yep. I’ve heard that before.
I just don’t see it.
I’ve sat in Model 3 for an afternoon riding the “charge current” to match excess production. The car does it seamlessly.
Consider that the Model 3 UI control to adjust “charge current” is just a “request”. On-board car software determines if the request makes sense. This would be the same way for a mothership “charge current” request.
Mothership Request: Charge at 4 amps.
Car Response: Sorry, lowest for this connection is 5.
Mothership Request: Charge at 35 amps.
Car Response: Sorry, max for this connection is 32.
The problem is not the expected use cases, but coming up with ones where it could be a problem. For example, there are aftermarket converters that allow you to plug a 14-50 into a lower rated plug. I also don't know what kind of wear switching charge current frequently puts on the car.
Every API feature they expose adds to the attack surface a malicious actor may use to try to cause problems. It could very well be that there doesn't turn out to be any significant issue to exposing this control, but it's reasonable not to expose it unless there is an important use case they want to cover.
Every API feature they expose adds to the attack surface a malicious actor may use to try to cause problems. It could very well be that there doesn't turn out to be any significant issue to exposing this control, but it's reasonable not to expose it unless there is an important use case they want to cover.
Consider, Powerwalls dynamically change charge current literally all day long.
I think Tesla kind of has this one in the bag.
For me, the use case is obvious: Solar direct is the most energy efficient way to charge.
I think they'll eventually implement the feature of charging using excess solar power, but I don't think that implies that they'll allow API access to charging current.
The kind of current change I'm talking about would be someone maliciously changing charge current from max to min ten times a second, for example, not using it in a reasonable way. Yes, obviously they could throttle changes, but it's not trivial to try to figure out what other kind of malicious uses somebody could come up with. This is why I'm saying there could be legitimate security reasons why they aren't implementing this feature.
The kind of current change I'm talking about would be someone maliciously changing charge current from max to min ten times a second, for example, not using it in a reasonable way. Yes, obviously they could throttle changes, but it's not trivial to try to figure out what other kind of malicious uses somebody could come up with. This is why I'm saying there could be legitimate security reasons why they aren't implementing this feature.
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