Advice on Wall Connector install

[dafish]

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then set an alert on the mains if you exceed abc. Soon enough you‘ll get an idea of actual power demand peaks.

 

[LostVector]

Looks like for that the EVSE and the dryer need to plug into the same box. What if the dryer is nowhere near the garage?

You might be able to combine a SplitVolt or Dryer Buddy with a 240V Power Tunnel (Power Tunnel™ 240 volt through wall extension).

It's not clear to me if adding up all of these options is any cheaper or better than your other alternatives however.

 

[brkaus]

Wasn’t there a Tesla device that goes on the main and can throttle the WC if necessary being tested?

 

[Mrbrock]

Just get a SPAN smart panel and you can throttle any circuit at any time. Or not allow certain circuits to turn on if other circuits are drawing.

 

[Cosmacelf]

Looks like for that the EVSE and the dryer need to plug into the same box. What if the dryer is nowhere near the garage?

Keep reading that page. At the bottom it links to the DCC-10 that will do what you want.

 

[SunnylandY]

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then set an alert on the mains if you exceed abc. Soon enough you‘ll get an idea of actual power demand peaks.

That's the ticket... what would be even better is a gadget like this intelligently communicating with the wall connector. Basically throttle the car to use no more than whatever is left over.
Now finding electricians who can understand all that and configure it would be challenging.

 

[SunnylandY]

Keep reading that page. At the bottom it links to the DCC-10 that will do what you want.

Thanks I see that now.
That's a lot more hardware though. Given that the car can vary it's draw some solution that monitors panel load could be comparatively simple. IDK if the wall connector can dynamically control the available current or if that's just communicated on the initial handshake. I suspect the latter.

 

[Mrbrock]

Thanks I see that now.
That's a lot more hardware though. Given that the car can vary it's draw some solution that monitors panel load could be comparatively simple. IDK if the wall connector can dynamically control the available current or if that's just communicated on the initial handshake. I suspect the latter.

The wall connector can vary current as evidenced by the initial setup where you select how much is available based on your breaker. With the right software and external sensors/inputs, it could easily vary in real time based on that data. But then you basicaly have the DCC-10.

 

[SunnylandY]

The wall connector can vary current as evidenced by the initial setup where you select how much is available based on your breaker. With the right software and external sensors/inputs, it could easily vary in real time based on that data. But then you basicaly have the DCC-10.

Right, but can that available current indication be varied *during* the charging session or is it communicated once at the time the connection is made and the contactor closed?

 

[SunnylandY]

The difference between what I am envisioning and the DCC10 thing is that it could be done with much less hardware. The smarts could all be in the wall connector and the only additional hardware would be something like that emporia gadget that measures the current on the panel mains. The wall connector would then be configured with two parameters, the wire/breaker size of the wall connector supply and the main breaker/service size.

 

[mongo]

Wasn’t there a Tesla device that goes on the main and can throttle the WC if necessary being tested?

Yup

 

[brkaus]

Yup

That would get me to buy a WC gen3. But I haven’t heard anything about it is a long time.

 

[mongo]

That would get me to buy a WC gen3. But I haven’t heard anything about it is a long time.

Race between Cybertruck and instrumented wall connector...
(Although... I could hack something I guess).

 

[brkaus]

Race between Cybertruck and instrumented wall connector...
(Although... I could hack something I guess).

Yea. Wouldn’t be too hard with the diy pi control for the gen2 WC. I’ve not looked at the api for the gen3. I’d guess electrical code approval on something like this would be the hard part.

 

[SunnylandY]

Yea. Wouldn’t be too hard with the diy pi control for the gen2 WC. I’ve not looked at the api for the gen3. I’d guess electrical code approval on something like this would be the hard part.

That might be the problem. There's a question of how quickly the wall connector and the car could respond to an increase in the load on the main, eg water heater or dryer switching on. Also how failsafe is it. The wall connector could only keep power flowing to the car in the presence of an uninterrupted signal from the panel gizmo indicating the load on the main is within limits. Lose the signal and wall connector needs to shut down.
You could have some smarts to keep the high water mark on the main. Part of the commissioning would be to run around the house and turn everything on.
I might get that emporia thing. I should also check to see whether Rocky Mountain power reports that on their website from the smart meter like FPL does

 

[brkaus]

The DCC kills the power to the evse but cannot throttle it so it only has that failsafe benefit. Of course that’s by opening the contactors so not exactly great.

Since the WC can theoretically vary the current the WC setup could be made reasonably safe by requiring a fixed amount of unused current. For example keeping 30a always “free”. The chance of multiple things ramping up super quick is pretty low. I’d wager that would even get decent charge rate overnight on a 60a panel.

the constant communication requirement is doable, but makes the system more susceptible to outages. Maybe a fallback of 12a if it cannot verify current house usage.

I have 200a service. 50a (40a) evse, 3 AC units, electric dryer, 2 electric ovens, a 5kw spa heater, and 4600 square ft of lighting and my panel has never been over 118a when measured at a 10 min average over the past 5 years.

 

[mongo]

To get fancier, one could apply a man in the middle attack on the control pilot signal to limit max charge rate.
However Gen 3 with power sharing open the possibility of a fake leader unit to control the real WC.

 

[SunnylandY]

I fooled around with it a little more. The Rocky Mountain Power website shows the kwh consumed over any one hour interval, similar to FPL. Unlike FPL however the RMP smart meter doesn't display the instantaneous power draw. Without acquiring anything new I suppose the best approximation would be to crank up the hot tub (pumps and heater) and run the dryer and anything else for a one hour period and see how many kwh were used according to the website. A crude effort but might be revealing. As brkaus described there's probably a "margin" applied at each device and this doesn't total up anywhere near what the numbers suggest.
That emporia thing would likely be better to really get a better assessment.

 

[Mrbrock]

Right, but can that available current indication be varied *during* the charging session or is it communicated once at the time the connection is made and the contactor closed?

Yes, it happens when either the car or HPWC sense increased temperatures and turns down amps to reduce temperatures. It’s all in the software. Just because it hasnt been programmed now, it could be in the future with the right inputs (in this case, voltage sensors on your main lines coming in).

 

[LostVector]

I fooled around with it a little more. The Rocky Mountain Power website shows the kwh consumed over any one hour interval, similar to FPL. Unlike FPL however the RMP smart meter doesn't display the instantaneous power draw. Without acquiring anything new I suppose the best approximation would be to crank up the hot tub (pumps and heater) and run the dryer and anything else for a one hour period and see how many kwh were used according to the website. A crude effort but might be revealing. As brkaus described there's probably a "margin" applied at each device and this doesn't total up anywhere near what the numbers suggest.
That emporia thing would likely be better to really get a better assessment.

What is your goal in doing this? I don't feel like playing in the safety margin of the load calculation is a great idea and as you mentioned, looking at the hourly stat on a website is extremely crude.

The fact is that having a hot tub on a 100A main breaker eats up all your headroom. Google for "hot tub 100a breaker" and you will see a lot of people feel like having a hot tub on 100A service is pretty much on the edge. Now add in the fact that you have an electric dryer. And now you want to further add continuous EV charging on top of that.

Let's say 50A for the hot tub and 30A for the dryer. That leaves just 20A for the rest of the house. A hair dryer or microwave would probably blow you past the limit. How realistic is it to add EV charging in on top of that?

I'm thinking this is obviously a no go. Use a splitvolt or upgrade to 200A service.