Rivian vs other home charger vs directly connected charge plug

[GA_Rivian]

I'm wondering about the advantages of the Rivian wall charger vs some other. The main reason I ask is that our electric provider is offering a discounted night charging rate via their installed charger. I haven't asked them yet if they will provide that rate with other chargers, but based on past actions I doubt it. If I'm lucky they'll allow it if the "non-approved" charger uses the appropriate AC powerline remote protocol.

So -- Does the Rivian charger provide any real benefits that wouldn't be present with a generic / other charger? Since the actual charge controller is in the vehicle, can I just buy a J1772 "nozzle" somewhere and install it? (I do lots of electrical wiring so I'm aware of issues around wire sizing, breakers, etc.)
Is it even possible to buy a 60A (48A actual) or 100A plug? The only one I've found so far is a 32A one.
This wikipedia article indicates the amperage max in the J1772 plug is determined by a resistor in the plug, but does not show a resistor specification for 60A max; it jumps from 32 to 100.

The article then indicates an updated J1772 standard where signaling is by IP to the "charging station" to negotiate the max amperage using IEEE 1901 or a related standard. That would imply a direct connection cannot be used for a J1772 "nozzle" without some vendor charging station. Is that true? Does the "old" resistor-controlled standard still work? Would a 100A plug work if I could find one? Pointers?

With a Rivian (or other) charger, can I program the charger to tell it the amperage of the cable/connector is a full 48A (or larger?)

If this is already answered, a pointer is fine. Thanks.

edit: Just found this plug/cable combo but it's not clear if it includes the resistor and would be direct-connectable, or if it requires a charging station for current negotiation.

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[VSG]

I'm wondering about the advantages of the Rivian wall charger vs some other. The main reason I ask is that our electric provider is offering a discounted night charging rate via their installed charger.

Chargers are essentially a commodity item. If your electric company gives incentives for specific chargers (many do), that's probably your best bet.

Compare chargers mainly on price and power. Features are secondary. The only exception I would make is if you ever plan to charge TWO cars in your garage, a charger that supports power sharing is a good forward-looking investment.

 

[VSG]

OK, I read the rest of your post. Some more answers from me ...

A Rivian can use at most 48A from a charger (tecnically called an EVSE since the actual charger is inside the vehicle). Any EVSE ("wall charger") that has a J1772 plug to plug into your Rivian can be used to charge your Rivian. If the EVSE is < 48A then the Rivian will charge at the max rate the EVSE can provide. If the EVSE is > 48A then the Rivian will not accept more than 48A. The Rivian (or other vehicle) and the EVSE will communicate over the J1772 and negotiate a rate when you plug in the Rivian. That negotiated rate will be the lower of the maximum the EVSE can provide and the maximum the Rivian can accept.

The National Electric Code specifies that for a continuous load (EVSE qualifies as continuous because it is expected to run at full power for many hours (>3?) at a time) you must have a circuit breaker rated for 125% of your load. So for a 48A EVSE you must have a 60A breaker. Because there are no NEMA 60A outlets, these EVSE are hardwired directly to the panel. For lower power EVSE, like a 40A EVSE (which requires a 50A breaker by the same 125% rule) you can find options that plug into an outlet - there are 40A EVSE that can plug into a NEMA 14-50 (50A) outlet for example. However, hardwired is safer if you have the choice.

 

[GA_Rivian]

A Rivian can use at most 48A from a charger ... If the EVSE is > 48A then the Rivian will not accept more than 48A. The Rivian (or other vehicle) and the EVSE will communicate over the J1772 and negotiate a rate when you plug in the Rivian. That negotiated rate will be the lower of the maximum the EVSE can provide and the maximum the Rivian can accept.

Thanks, I understand the communicating part, but didn't know about the 48A Rivian limit. But what if there is NO EVSE, only a directly connected plug? The plug itself, in the original J1772 spec, contains a resistor which specifies the max current. That implies no need for any other communication. The communication was added in a later version of the spec. Will a Rivian charge properly from an older, non communicating, plug? I'm guessing it will, but it would be nice to know.

 

[GatorRiv]

Agree with the poster who implied that any well reviewed brand properly installed probably offers comparable abilities. I've never had the Rivian charger, perhaps disqualifying my opinion, but I understand other chargers have more flexible features in their apps.

I've now had two hardwired chargers at 48amps and they do what they say......they deliver 48amps and provide all the scheduling and nerdy features you could want. I think, based on what I read here, that the Rivian charger is certainly competent but overpriced.

 

[HaveBlue]

All the charging happens in the car. The rivian has a 12kw charger. I don't think the wall unit can limit the current. They can only signal what they are able to supply. The car could theorhetically ignore the signal and draw more or less up to 12kw to the peril of the breaker and wiring. If you've ever used a stick welder, the hardware to modulate current requires a variable transformer which is pretty beefy; either with movable primary and secondary windings or taps in windings for different current output. The wall units have no such thing. Even an inverter charger that's smart will have some beef for all that power. The car does everything in AC charging. Ignoring all the bells and whistles like bt wifi etc, the wall unit has relays to isolate power to the cord that is tested along with GFCI protection.

Here's what is interesting, but I haven't seen this first hand. My business partner, who doesn't own an EV but has a contractors license, says his neighbor charges his Tesla with a cable wired straight to the wall in his garage. Sounds sketch but could be possible if his circuit is bigger than the car converter.

Although using a simple resistor on the proximity pilot might be possible (100ohm to answer your question), the control pilot can use pulse width modulation to communicate current as well. This assumes the car will ignore all the other analog communication that happens on initiating the charge such as vehicle sense. These functions are largely for the wall units benefit though.

So will a simple wire work? Maybe I'll get a tour of the neighbor's setup one day and see if is truly that or a mobile charger in reality.

 

[SANZC02]

…So will a simple wire work? Maybe I'll get a tour of the neighbor's setup one day and see if is truly that or a mobile charger in reality.

I do not think it would, there is a handshake between the external unit and the internal AC charger. If they are not properly communicating the onboard charger will not initialize.

There is similar handshaking for DC charging and without the proper handshake it will not initiate a DC session.

 

[GA_Rivian]

Here's what is interesting, but I haven't seen this first hand. My business partner, who doesn't own an EV but has a contractors license, says his neighbor charges his Tesla with a cable wired straight to the wall in his garage. Sounds sketch but could be possible if his circuit is bigger than the car converter.

Although using a simple resistor on the proximity pilot might be possible (100ohm to answer your question), the control pilot can use pulse width modulation to communicate current as well. This assumes the car will ignore all the other analog communication that happens on initiating the charge such as vehicle sense. These functions are largely for the wall units benefit though.

So will a simple wire work? Maybe I'll get a tour of the neighbor's setup one day and see if is truly that or a mobile charger in reality.

Thanks, I would really like to know how that is wired. On re-reading the J1772 spec I don't think it will work without the PWM handshake, despite the resistor on the proximity pin indicating what the max amperage is.

 

[NY_Rob]

Thanks, I would really like to know how that is wired. On re-reading the J1772 spec I don't think it will work without the PWM handshake, despite the resistor on the proximity pin indicating what the max amperage is.

It will 100% not work without the handshake and correct communication protocols. These are safeguards that make the system safe to operate even under wet conditions. No handshake, no juice

 

[sub]

The National Electric Code specifies that for a continuous load (EVSE qualifies as continuous because it is expected to run at full power for many hours (>3?) at a time) you must have a circuit breaker rated for 125% of your load. So for a 48A EVSE you must have a 60A breaker. Because there are no NEMA 60A outlets, these EVSE are hardwired directly to the panel. For lower power EVSE, like a 40A EVSE (which requires a 50A breaker by the same 125% rule) you can find options that plug into an outlet - there are 40A EVSE that can plug into a NEMA 14-50 (50A) outlet for example. However, hardwired is safer if you have the choice.

I am sure that someone makes a 40A charger with a 14-50 plug, that is not the norm. Many 14-50 chargers, including the one that comes with your Rivian, are limited to 32 amps rather than 40.

This is because electric code permits 14-50 outlets to be used on 40 amp breakers or 50 amp breakers. While it would be safe to pull 40 amps from a 14-50 outlet if it was attached to a 50 amp breaker, the charger doesn't know if it is attached to a 40 amp breaker or a 50 amp breaker so to be safe it assumes it is a 40a breaker and limits you to 32 amps.

32 amps is going to be sufficient for most people, but if you want to get more than 32 amps of charging you will probably want a hardwired charger.

 

[HaveBlue]

Most chargers have a simple setting to set the breaker and delivery current. The Autel ones have a rotary switch internally to set delivery from 16A-48A. Some brands allow it set via their app.
Putting a 40A breaker on a 50A 14-50 outlet is going to cause nuisance tripping for someone if they plug in a 40A draw charger. It would be good to label it. If the wire is only #8 you don't have a choice. The breaker is there to protect the wiring.
You can use a 60A breaker on a 14-50 plug assuming the wire is at least #6thhn. Since the 14-50 plug cannot accommodate a (UL) device that will draw more than 50A (40 contin), the circuit would be fine. Some cheap 14-50 outlets cannot handle 50A or even 40A continuously so really a 50A breaker is appropriate but still use #6 or better wire to future proof if you can.

For the Rivian, the recommendation is to buy a 48A wall unit and hardwire it to a 60A breaker and rated wire for the fastest AC charging speed if the panel passes a load calculation. The included mobile connector is good for 32A.

Some vehicles have up to a 19kw onboard charger an can utilize a 80A service/100A breaker connection.

BTW Duosida has really bad reviews and isn't properly UL listed. Buy a name brand.

 

[BigSkies]

One consideration I missed is that my utility (XCEL Colorado) offers a small discount for charging in off hours.

Except you need one of their pre-approved Wi-Fi enabled chargers that can connect to XCEL and tell them when you’re charging.

I don’t think this is super common, but it’s worth looking at your utility programs before making a purchase decision. The discount isn’t big enough to justify buying a new charger, but I would have made a different charger decision if I had looked at it in advance.

 

[GA_Rivian]

One consideration I missed is that my utility (XCEL Colorado) offers a small discount for charging in off hours.

Except you need one of their pre-approved Wi-Fi enabled chargers that can connect to XCEL and tell them when you’re charging.

I don’t think this is super common, but it’s worth looking at your utility programs before making a purchase decision. The discount isn’t big enough to justify buying a new charger, but I would have made a different charger decision if I had looked at it in advance.

Thanks, my utility (local REA) has a similar program, which is one reason for the original post. I originally thought the wi-fi was for communication with the vehicle, but it appears it is for communication with the utility, which seems stupid -- they should be able to use power-line signaling. For me that's a problem, as we have no wi-fi where the charger would be located. Also unfortunately, the program from my utility is only a rental, and it's a plug-in charging station maxed out at 32A. I see the XCEL one includes a 48A hard-wired option.

 

[BigSkies]

Thanks, my utility (local REA) has a similar program, which is one reason for the original post. I originally thought the wi-fi was for communication with the vehicle, but it appears it is for communication with the utility, which seems stupid -- they should be able to use power-line signaling. For me that's a problem, as we have no wi-fi where the charger would be located. Also unfortunately, the program from my utility is only a rental, and it's a plug-in charging station maxed out at 32A. I see the XCEL one includes a 48A hard-wired option.

32A is fine for most people. I'd insist on more if you're consistently using maybe 50%+ of the battery in a day. But most people don't do that. I have a Grizzl-E duo that charges my car either at 20A, 32A or (I think) 38A depending on whether my Tesla is plugged in and charging at the same time. Even 20A is fine for my day-to-day usage, but it might be limiting if I'm doing a lot of back-to-back long drive days.

In your case, I don't care for the rental aspect. But that's just a personal bias. So it's really a question of whether getting Wifi to the garage is worth the value of the discount they're providing. I'd personally pass if it is something similar to XCEL's $50/year discount but look at it if it's something more substantial.

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