Wall Connector Amperage Modulation

[rentien]

Hi All,
New to the forum, so please excuse any newbie questions.
I am asking this in a theoretical sense.
My question is, why doesn't tesla have something that measures amperage at the main breaker, so then the wall connector could control amperage given to charging the car, so you can maximum use out of the breaker.
For example, say I have a 100A breaker (limit i want to stay under to avoid tripping the breaker is 80A).
It is recommended to put a 30A breaker, so charge at 24A. Let's say I'm charging for 6 hours to get to the charge level i want to get to in the car. However, I also want to... use the drier, stove, oven, microwave because i'm preparing for a party. Most likely i can't do all these things for 6 hours because i'd be over the 80A limit.
However, if the wall connector could measure current at the main breaker, and fill in the rest, so for example, charge at 48A for 3 hours, and then i could do the rest in three hours, or I could use some things and the charger would adjust amperage to the car to keep the total amperage at the main at 80A i could more effectly use the 80A I have. One would make more effective use of your 80A (times time) if you charge at a higher amperage when things aren't being used, so finish charging the car as quickly as possible and then leave your house free to run other things. This would also be less worrying then turning up and down amperage manually tot he charger to account for this.
Only issue I could see if that if your measurement of amperage at the main was slow or incorrect, you could end up accidentally going over your limit and tripping your breaker.

 

[EVRider-FL]

I don’t know how the Wall Connector could determine what’s happening elsewhere on your home electrical service. My Gen 2 Wall Connector has to be configured to tell it the amperage of the circuit breaker it’s connected to, and that’s all it knows. The Wall Connector will automatically adapt to lower amperages if it can’t draw the full load as configured. Maybe there are other devices that can manage your electric service in the way that you want.

 

[brkaus]

@rentien it would be great if it could happen. There are solutions out there like the DCC-9 that will monitor the main and cut the power to the EVSE, but that seams pretty harsh.

I’m guessing the biggest issue is no one would approve it without a bunch of fail safes so nothing bad happens.

 

[beatle]

Are you referring to 100A service into your main panel? If so, you're not limited to 80A there. The 20% circuit derating is just for constant loads like your EVSE circuit. You can easily overprovision your panel to 200%. Most of your circuits will be nowhere near their capacity.

 

[brkaus]

Are you referring to 100A service into your main panel? If so, you're not limited to 80A there. The 20% circuit derating is just for constant loads like your EVSE circuit. You can easily overprovision your panel to 200%. Most of your circuits will be nowhere near their capacity.

Right. But if the EVSE could watch the main power line and modulate the EVSE down as other items turn on like a electric dryer or the oven, then the load calculations could be optimized.

 

[beatle]

Something like this then?

Siemens' new home EV charger adapter ends need for electrical panel upgrades

Siemens' game-changing EV charger adapter can end costly electrical panel upgrades and enable home chargers to be connected in minutes.

electrek.co

 

[brkaus]

Something like this then?

Siemens' new home EV charger adapter ends need for electrical panel upgrades

Siemens' game-changing EV charger adapter can end costly electrical panel upgrades and enable home chargers to be connected in minutes.

electrek.co

Cool. Available early 2023. We will see! Pricing will be important as would utility acceptance.

 

[rentien]

I don’t know how the Wall Connector could determine what’s happening elsewhere on your home electrical service. My Gen 2 Wall Connector has to be configured to tell it the amperage of the circuit breaker it’s connected to, and that’s all it knows. The Wall Connector will automatically adapt to lower amperages if it can’t draw the full load as configured. Maybe there are other devices that can manage your electric service in the way that you want.

Either it would be some EE trickery way, by looking at current and waveforms, etc., or simply an additional device that constantly measures current at the main breaker to stay under 80A.
So a wireless device or even... wired device that goes from main breaker to wall charger. That was the thought anyway.

 

[rentien]

Are you referring to 100A service into your main panel? If so, you're not limited to 80A there. The 20% circuit derating is just for constant loads like your EVSE circuit. You can easily overprovision your panel to 200%. Most of your circuits will be nowhere near their capacity.

Yeah, so my thinking was:

Say I put a 60amp (48 amp draw) breaker to the wall charger.
And then whenever I use the oven, etc. then constant current draw gets to 80A so wall connector decreases current draw to keep it at 80A and not go over.
As soon as the oven etc. is done being used, it goes back up to maximum 48A.
The benefit, is that if you're using nothing (most of the time at night), for a 100A main breaker, I could be pulling 48A and charging very quickly and safely if this worked properly. So I could get faster charge times, and more efficiently use the 80A limit.
Instead of making the rough standard estimate most people make, where 100amp main breaker means 30A breaker for EV charger meaning i can only pull 24A.

 

[rentien]

Something like this then?

Siemens' new home EV charger adapter ends need for electrical panel upgrades

Siemens' game-changing EV charger adapter can end costly electrical panel upgrades and enable home chargers to be connected in minutes.

electrek.co

Isn't this a cheaper way to get power to the EV charger, but doesn't change charge amperage based on available amperage?

Still cool none the less. Wish this came out earlier so I could have used it!

 

[brkaus]

Isn't this a cheaper way to get power to the EV charger, but doesn't change charge amperage based on available amperage?

Still cool none the less. Wish this came out earlier so I could have used it!

The text mentions something about power management. But since it isn’t yet a product, details are scarce.

 

[brkaus]

“The new adapter will enable electric car owners to charge their EVs by connecting chargers directly through the meter socket, which is on every home. It provides more useable capacity by monitoring total load and controlling the EV circuit to ensure the total capacity rating is within the limit.”

 

[beatle]

Isn't this a cheaper way to get power to the EV charger, but doesn't change charge amperage based on available amperage?

Still cool none the less. Wish this came out earlier so I could have used it!

It could be cheaper if it lets you avoid a panel upgrade. It does say that it controls the EV circuit presumably when overall usage is otherwise high.

But really, charging at only 24A is pretty good for daily driving. I charge at 24A at my parents' home and 16A at my girlfriend's parents' home. On my 2019 Model S I get ~5% an hour at my parents and ~3% an hour at hers. On my 2015 those numbers were a bit higher since the battery was smaller. On a 3/Y the percentage per hour would be higher still. Not ideal if you roll in at night with 10% and need to leave the next morning at 100%, but it's plenty to fill up to 90% otherwise.

 

[rentien]

“The new adapter will enable electric car owners to charge their EVs by connecting chargers directly through the meter socket, which is on every home. It provides more useable capacity by monitoring total load and controlling the EV circuit to ensure the total capacity rating is within the limit.”

oh cool! i knew someone had to have already thought of this

 

[rentien]

It could be cheaper if it lets you avoid a panel upgrade. It does say that it controls the EV circuit presumably when overall usage is otherwise high.

But really, charging at only 24A is pretty good for daily driving. I charge at 24A at my parents' home and 16A at my girlfriend's parents' home. On my 2019 Model S I get ~5% an hour at my parents and ~3% an hour at hers. On my 2015 those numbers were a bit higher since the battery was smaller. On a 3/Y the percentage per hour would be higher still. Not ideal if you roll in at night with 10% and need to leave the next morning at 100%, but it's plenty to fill up to 90% otherwise.

but... if you wanted to complete charging even faster to clear your house of EV charging so power could be used for otehr things (say a party so need to use stove, oven, microwave, and washer/drier... then it could be helpful to charge faster so you can more total usage khwr's pulled...
So not all just about charging EV faster for use. It could also be this though. This would allow for faster charge rates while also not tripping the breaker automatically... instead of... me thinking about if we're going to run everything, I should turn charging off on my car, etc.

 

[rentien]

but... if you wanted to complete charging even faster to clear your house of EV charging so power could be used for otehr things (say a party so need to use stove, oven, microwave, and washer/drier... then it could be helpful to charge faster so you can more total usage khwr's pulled...
So not all just about charging EV faster for use. It could also be this though. This would allow for faster charge rates while also not tripping the breaker automatically... instead of... me thinking about if we're going to run everything, I should turn charging off on my car, etc.

but yeah 24A is mostly good enough for me too.

 

[Rocky_H]

@rentien The EVSE charging device can't do this, because it has to be on a dedicated separate branch circuit. (basically a sub-circuit under the main) So therefore, that is all it will be able to sense. It can't sense what's going on in your main feed of the main breaker in your panel.

Maybe there are other devices that can manage your electric service in the way that you want.

Yes, there is a device that does exactly this.

There are solutions out there like the DCC-9 that will monitor the main and cut the power to the EVSE,

Yes, the DCC-9 line of products are what does this. This is what you're looking for, @rentien . This monitors your main feed amp usage and can control the amp output allowed into that branch circuit that the EVSE is using.

 

[RTPEV]

I think most people would be content with simply charging their vehicle overnight, not while they are drying clothes and cooking dinner. And also, 24-30A is probably going to be sufficient 95-100% of the time. Instead of "clearing the EV charging faster" to make way for all those other items, just "clear the other items" first and charge later.

To work around this, all you really need to do is set the charge limit at home to 24A, and then on whatever occasions you need to quickly charge, crank it up and just make sure you don't use heavy appliances during that time.

With long range vehicles (300+ miles), I feel that it would take a combination of very bad planning and extreme usage to run into a situation where you had to get your car charged quickly, or before or during times of heavy electricity use rather than just charging it overnight. If my assumption is true, then I think the market size for such a device/capability would be pretty small.

All that said, yes, it is technically possible to have a charging station do what you want it to. There are already smart EVSEs that can respond to current grid conditions (they are typically set up to only turn on when grid renewable content is high, but the point being, they are able to programmatically respond to some external factor), and smart meters and smart panels today are able to measure total (or circuit by circuit) power consumption, so it would be technically feasible to combine the two to have a smart controller capable of modulating the EVSE power output appropriately. I just doubt you will find a big enough market to warrant a mass market product development. It would be a fun hobbyist project though.

 

[brkaus]

@rentien The EVSE charging device can't do this, because it has to be on a dedicated separate branch circuit. (basically a sub-circuit under the main) So therefore, that is all it will be able to sense. It can't sense what's going on in your main feed of the main breaker in your panel.


Yes, there is a device that does exactly this.

Yes, the DCC-9 line of products are what does this. This is what you're looking for, @rentien . This monitors your main feed amp usage and can control the amp output allowed into that branch circuit that the EVSE is using.

The part the DCC-9 is missing is attempting to work with the car first, before just cutting the relay.