We need 277 volt AC compatible charging. Really.

McRat

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In the US, we use the following 'low voltage' AC services that EVs can digest:

120 vac - This is found everywhere, homes, businesses, public buildings. It is seldom found in parking lot lights and street lights.
240 vac - This is also available at houses and apartments. This is usually not an option at commercial and public buildings.

208 vac - This is the 3 phase power that is found at commercial and public buildings which EVs can absorb.
277 vac - This is one leg of 480 vac 3 phase power, which is found at commercial and public buildings. This is what most of your street lights, parking lot lights, and warehouse lighting is. Tesla doesn't advertise this anymore, but they can all charge off 277 as of 2021.

The charging speed is in this order:
120 vac - base
208 vac - 173% as fast
240 vac - 200% as fast
277 vac - 231% as fast

The kicker is the 277v advantage over 208v at businesses and public buildings - 133% as fast.

When you install L2 charging at a commercial or public buildings, you normally set it up for 208 vac. Why? 240 volts isn't available.
But 277 vac is available, why can't we use that? Because only Tesla supports it. All other brands do not AFAIK.





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Gshenderson

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The kicker is the 277v advantage over 208v at businesses and public buildings - 133% as fast.
I believe that difference would be stated as “33% faster”, not 133% which would imply more than twice as fast.
 

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I believe that difference would be stated as “33% faster”, not 133% which would imply more than twice as fast.
I think his statement is correct, he is not saying it is 133% faster but 133% as fast which is 25% faster.

An example is if in 60 minutes at 208 volts you were able to get 100kw, then in 60 minutes at 277 volts you would get 133 kwh 133% as fast). When you break that down to kwh per minutes at 208 it is 1.66 and at 277 it is 2.21 so to get the same 100kwh at 208 it is 60 minutes at 277 it is 45 minutes (25% faster).

The numbers above are just for an example, they are not meant to be actual charge times.
 
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I believe that difference would be stated as “33% faster”, not 133% which would imply more than twice as fast.
I state performance numbers that way to make the math easier. Both are correct. But sometimes people will try to divide by 33% or 67% to get the performance improvement. Both are wrong. They need to multiply by (1+33%) to get the right answer.
 

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I'm lost is this thread referencing L2 charge times? If so isn't the charge rate bound by the on board 11.5KWh charger? My understanding is that using 277 vs 208v would result in needing less current to deliver the same amount of watts not delivering more watts at the same current. Ohms law states P=I*E given 11.5KW I and E would have an inverse relationship, What am I missing?
 

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DucRider

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I'm lost is this thread referencing L2 charge times? If so isn't the charge rate bound by the on board 11.5KWh charger? My understanding is that using 277 vs 208v would result in needing less current to deliver the same amount of watts not delivering more watts at the same current. Ohms law states P=I*E given 11.5KW I and E would have an inverse relationship, What am I missing?
The J1772 standard ignores voltage and is focused on amps.
The on-board charger will negotiate with the EVSE for a mutually acceptable amperage. A relay is then tripped and the AC from the wall is fed to the vehicles charger (120, 208, 240, etc.). The J1772 standard allows for up to 240V. Tesla does not use the J1772 connector and is not limited by those standards (they use the protocols with some "extensions").
If an otherwise J1772 compliant EVSE was wired to a 277V circuit and a strictly J1772 compliant EV plugged in, 277V would be fed to a charger that is likely only designed for 240V. The EVSE has no way to advertise/signal what voltage it will provide.
For Rivian to implement 277V, they would need to move to a different connector and then provide an adapter to enable use of standard J1772 and CCS1 equipment. The added cost, complexity and inconvenience of not adhering to the limitations of the J1772 and CCS standards probably isn't justified for slightly faster L2 charging from a small percentage of installations.

As an interesting side note, the 208 vs 240 issue is why you see many EVs that rate their on-board L2 charging at 6.6 kW drawing 7.7 kW.
32A @ 208V gets you to the 6.6 rating, but when a 32A charge session is done on a 240V circuit the rate is higher. These companies spec to the minimum kW that will be provided by a J1772 EVSE for a given amperage.
 
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Here are the advantages of designing 277-capable EVs:

Availability:
Many locations are 277 only. Parking lots and light poles come to mind. Allowing L2 charging during the day at light poles at the back of the lots is a great way to extend infrastructure for very little money.​
208 and 120 are not an option in many parking lots, only 277 and 480 (two legs) can be provided without cutting trenches in the pavement. You can't run 120 (208) in the same conduit as 277/480.​
Wiring:
Thinner wire gauges can be used with 277 as well as smaller breakers. This lowers the cost at ALL commercial locations. 277 also has lower losses.​
Protocol:
This is not as big a challenge as many think. It does not require a new connector. The biggest problem is that for optimal efficiency, the onboard charger must be designed knowing that 277 can be used. Keep in mind that many lighting fixtures you see in buildings accept 120-277 volts right out of the box. Off-the-shelf J1772 EVSE boxes handle at least 90 to 264 vac at a minimum.​

I predict at some future point both SAE and EV mfrs will figure this out, and it will be an option. Tesla engineers figured it out, so it can't be that hard.
 

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Protocol:
This is not as big a challenge as many think. It does not require a new connector. The biggest problem is that for optimal efficiency, the onboard charger must be designed knowing that 277 can be used. Keep in mind that many lighting fixtures you see in buildings accept 120-277 volts right out of the box. Off-the-shelf J1772 EVSE boxes handle at least 90 to 264 vac at a minimum.
J1772 cannot communicate voltage, and the spec is for 208-240V. If Rivian wants to enable 277V, they cannot use the J1772/CCS1 connector. A J1772 plug that provides voltage over the spec would certainly cause problems with many EVs.
An EVSE could easily be wired to put 277V (or more) thru the J1772, but most vehicles plugging in are likely to be designed for 240V max (+/- a buffer). Indeed most chargers are specced at 264V max (240V +10%). Would putting 277V (+/- 10%) let the magic smoke out of the on-board charger? Maybe, maybe not - but maybe not isn't good enough. The problem is not that the connector cannot handle 277V, but that vehicles plugging in might not.

Tesla does not use the J1772 connector and were not limited by the specs for that standard. Rivian will be using J1772 and therefore is limited by the standard.
 

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Parking lots and light poles come to mind. Allowing L2 charging during the day at light poles at the back of the lots is a great way to extend infrastructure for very little money.
No light pole in a parking lot is wired with the 6AWG cable that would be required for the ~9kW (277V 35A) that it would be providing. That’s at least ten times the current draw of the lamps at the top. Very little money is not how I would describe rewiring all the lampposts in a parking lot.
 

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Since having an EV since 2012+ home charging has never been a speed issue, even say at 32 amps on a 240v outlet. The only time charging speed made any concern to me was on road trips that 1% of the ownership time max.
 
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No light pole in a parking lot is wired with the 6AWG cable that would be required for the ~9kW (277V 35A) that it would be providing. That’s at least ten times the current draw of the lamps at the top. Very little money is not how I would describe rewiring all the lampposts in a parking lot.
It doesn't have to be 9 kW, and yes, you can pull wire. What you CAN'T do is pull 120/240 volt wire in the conduit.

Essentially, to set up a commercial lot with 240v you must cut through the pavement and trench it. That's why you don't see much L2 charging in parking lots.
 

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My garage, wired about a year ago has a 50AMP 240 volt receptacle in front of the 3, soon to be 4 bays. I'm hoping I can get a fairly fast charge on my R1T when it comes home to roost. I have a Mean Greene Rival mower that will be charged from one of those receptacles. I have enough solar to handle charging 3 at once. That's what the solar installers tell me.
 

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My garage, wired about a year ago has a 50AMP 240 volt receptacle in front of the 3, soon to be 4 bays. I'm hoping I can get a fairly fast charge on my R1T when it comes home to roost. I have a Mean Greene Rival mower that will be charged from one of those receptacles. I have enough solar to handle charging 3 at once. That's what the solar installers tell me.
You’ll likely get 15-16 miles of range per hour of charge if you simply plug into that outlet. You could perhaps get up to 25 miles per hour if you remove the outlet and hardwire a 60amp EVSE into the same wiring. You’d need to change out the breaker to a 60amp and make sure the wiring is heavy enough to support that.
 

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You’ll likely get 15-16 miles of range per hour of charge if you simply plug into that outlet. You could perhaps get up to 25 miles per hour if you remove the outlet and hardwire a 60amp EVSE into the same wiring. You’d need to change out the breaker to a 60amp and make sure the wiring is heavy enough to support that.
A 50 A circuit with 40A EVSE should get you 20 miles/hour.
The Rivian included charge cord with the 14-50 plug gets you 16 miles/hour @ 32A, and a 48A EVSE will get you 25 miles/hour. Using a 40A EVSE should land you around 20.
 

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