Amping down for a wall outlet is capped at 14 Amps?

[Lawrence-of-Blaine]

I’ve had my R1S for about three months, and have made numerous trips from MSP area to my cabin in northern WI. For now, I’m charging up north on a wall outlet, but— it’s a 20 amp outlet, a GFI actually, and a 20 amp rated one at that…which I wired with 12/2. And of course it’s on a 20 amp breaker. So from what I can tell, the entire stream is rated for 20.
Problem is, the vehicle always defaults to 14 amps. I can set the amperage to 18 or 16, etc. but as soon as I plug in, it drops back to 14. Is this a bug? Or is there another adapter I need that didn’t come with the vehicle?
Any info is much appreciated.

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[SPITmadFIRE]

I’ve had my R1S for about three months, and have made numerous trips from MSP area to my cabin in northern WI. For now, I’m charging up north on a wall outlet, but— it’s a 20 amp outlet, a GFI actually, and a 20 amp rated one at that…which I wired with 12/2. And of course it’s on a 20 amp breaker. So from what I can tell, the entire stream is rated for 20.
Problem is, the vehicle always defaults to 14 amps. I can set the amperage to 18 or 16, etc. but as soon as I plug in, it drops back to 14. Is this a bug? Or is there another adapter I need that didn’t come with the vehicle?
Any info is much appreciated.

For sustained loads like vehicle charging on most circuits with standard breakers, you should not exceed 80% of the breaker's rating. This means for a 20A breaker, 16A is the maximum safe current setting.

That said, if you're using the Rivian portable charger with the 120V adapter, the vehicle should not allow you to exceed 12A of current I believe. That's the max the portable charger can handle through the 120V adapter. If you're using the 240V adapter, then I'm not sure why you wouldn't be able to sustain the 16A max.

 

[R.I.P.]

I’ve had my R1S for about three months, and have made numerous trips from MSP area to my cabin in northern WI. For now, I’m charging up north on a wall outlet, but— it’s a 20 amp outlet, a GFI actually, and a 20 amp rated one at that…which I wired with 12/2. And of course it’s on a 20 amp breaker. So from what I can tell, the entire stream is rated for 20.
Problem is, the vehicle always defaults to 14 amps. I can set the amperage to 18 or 16, etc. but as soon as I plug in, it drops back to 14. Is this a bug? Or is there another adapter I need that didn’t come with the vehicle?
Any info is much appreciated.

A Tesla mobile EVSE will charge from a 20a 110 outlet at 16a, if the line passes it's tests. That is the maximum allowed for constant pull (80%). Not much of a bump, but if you mobile charge often, there are other reasons to carry/use the Tesla unit.

 

[PhatDaddy]

@R.I.P. , based on your feedback and other research I recently purchased the Tesla Mobil EVSE and the NEMA adapter bundle. They haven’t arrived yet, but a question occurred to me belatedly… will I have to use Tesla’s app to charge using the Tesla Mobil charger? Will I now have to use 2 different app to remote check on the status of my charging?

 

[zfischer]

will I have to use Tesla’s app to charge using the Tesla Mobil charger?
[/QUOTE]

Nope. Just plug it in and charge. No app use required.

 

[PhatDaddy]

Nope. Just plug it in and charge. No app use required.

Good to hear. Thanks.

 

[VSG]

Portable chargers like the Rivian charger "know" which adapter accessory cable is being used, and automatically set the current accordingly. The Rivian portable charger comes with just two adapter cables - one with a NEMA 5-15 plug and one with a NEMA 14-50 plug.

If you are using the NEMA 5-15, the Rivian charger thinks you're on a 15A circuit and won't let you draw more than 80% of that - max 12A. (I'm not sure why, but the vehicle display always seems to read 2kW higher for some reason.)

So as it stands, the Rivian portable charger has no way of telling you're on a 20A circuit and won't let you draw 16A from what it thinks is a 15A circuit. If Rivian had additional adapter cables available like the Tesla kit does, you could use a NEMA 5-20 adapter to plug into your NEMA 5-20 outlet and the Rivian portable charger would know you're on a 20A circuit and would automatically set the rate to 16A (80% of 20A).

 

[Lawrence-of-Blaine]

Thanks to all. I learned a thing or two here.

 

[PhatDaddy]

Portable chargers like the Rivian charger "know" which adapter accessory cable is being used, and automatically set the current accordingly. The Rivian portable charger comes with just two adapter cables - one with a NEMA 5-15 plug and one with a NEMA 14-50 plug.

If you are using the NEMA 5-15, the Rivian charger thinks you're on a 15A circuit and won't let you draw more than 80% of that - max 12A. (I'm not sure why, but the vehicle display always seems to read 2kW higher for some reason.)

So as it stands, the Rivian portable charger has no way of telling you're on a 20A circuit and won't let you draw 16A from what it thinks is a 15A circuit. If Rivian had additional adapter cables available like the Tesla kit does, you could use a NEMA 5-20 adapter to plug into your NEMA 5-20 outlet and the Rivian portable charger would know you're on a 20A circuit and would automatically set the rate to 16A (80% of 20A).

Are you suggesting the Rivian portable charger has basically the same ‘smarts’ as the Tesla one… just that the adapters are not available from Rivian to allow us to take advantage of the Rivian charger’s capabilities? That seems counter to other people’s comments that the Tesla portable charger has additional intelligence/sensors built in that allow greater capabilities and safety features. Could you provide some source information… I’d really like to understand the full capabilities of the Rivian charger just in case Rivian eventually makes additional adapters available.

 

[R.I.P.]

@R.I.P. , based on your feedback and other research I recently purchased the Tesla Mobil EVSE and the NEMA adapter bundle. They haven’t arrived yet, but a question occurred to me belatedly… will I have to use Tesla’s app to charge using the Tesla Mobil charger? Will I now have to use 2 different app to remote check on the status of my charging?

Nope

 

[ksujeff99]

I’ve had my R1S for about three months, and have made numerous trips from MSP area to my cabin in northern WI. For now, I’m charging up north on a wall outlet, but— it’s a 20 amp outlet, a GFI actually, and a 20 amp rated one at that…which I wired with 12/2. And of course it’s on a 20 amp breaker. So from what I can tell, the entire stream is rated for 20.
Problem is, the vehicle always defaults to 14 amps. I can set the amperage to 18 or 16, etc. but as soon as I plug in, it drops back to 14. Is this a bug? Or is there another adapter I need that didn’t come with the vehicle?
Any info is much appreciated.

You can buy a 5-15 to 14-50 adapter and charge at 16a. I did it this summer at a relative’s house and it worked perfectly. You have to make sure you drop down the charging rate in the truck as it will default to 32a when the 14-50 pigtail is plugged into the mobile charger.

Note that you’re only getting 110v through this setup (rather than the typical 220v coming through a 14-50 outlet) but the truck manages it just fine.

Going from 12a to 16a is only a 33% increase but the energy going to the battery will be more than a 33% improvement since the charging overhead remains the same. In other words, at 12a maybe only 8a is used for charging and 4a for overhead to run the electronics, etc. At 16a, the same 4a overhead applies but you’ll get 12a going to the battery–a 50% improvement.

 

[R.I.P.]

You can buy a 5-15 to 14-50 adapter and charge at 16a. I did it this summer at a relative’s house and it worked perfectly. You have to make sure you drop down the charging rate in the truck as it will default to 32a when the 14-50 pigtail is plugged into the mobile charger.

Note that you’re only getting 110v through this setup (rather than the typical 220v coming through a 14-50 outlet) but the truck manages it just fine.

Going from 12a to 16a is only a 33% increase but the energy going to the battery will be more than a 33% improvement since the charging overhead remains the same. In other words, at 12a maybe only 8a is used for charging and 4a for overhead to run the electronics, etc. At 16a, the same 4a overhead applies but you’ll get 12a going to the battery–a 50% improvement.

This is a ham-fisted way of doing it and fires can result. The Rivian EVSE will just keep pulling if things get hot with this setup.

But yeah... People do it.

 

[VSG]

This is a ham-fisted way of doing it and fires can result. The Rivian EVSE will just keep pulling if things get hot with this setup.

But yeah... People do it.

Yeah. The big problem is you might forget to lower the current draw from your Rivian screen. Whenever you introduce a source of human error like this, there WILL be human error at some point.

 

[VSG]

Are you suggesting the Rivian portable charger has basically the same ‘smarts’ as the Tesla one… just that the adapters are not available from Rivian to allow us to take advantage of the Rivian charger’s capabilities? That seems counter to other people’s comments that the Tesla portable charger has additional intelligence/sensors built in that allow greater capabilities and safety features. Could you provide some source information… I’d really like to understand the full capabilities of the Rivian charger just in case Rivian eventually makes additional adapters available.

Whoa there pardner. You made a wrong turn at Albuquerque and just kept right on going. I didn't say or imply any of this. In particular the only thing I said about the Tesla charger is that you can buy additional adapter cables for it.

I said:

Portable chargers like the Rivian charger "know" which adapter accessory cable is being used

The TL;DR version of that is as follows:

Portable chargers typically have a charger body, a permanently-attached long charger cable with (e.g.) a J1772 plug at the end, and a set of short detachable adapter cables that connect the charger body to the wall outlet.

In the case of the Rivian charger, each of those short adapter cables has a NEMA plug at one end and a proprietary 5-pin plug at the other. This 5-pin plug gets inserted into the charger body.

Here's where the magic comes in. The short adapter cable has an internal resistor which the charger body can use to identify which short adapter cable is plugged into the body. So the short adapter cable with the NEMA 5-15 plug on one end self-identifies as a 15A circuit by the value of the resistor. The charger measures the resistor, which tells it that the short adapter is on a 15A circuit, and thus the charger will not deliver more than 12A to the short adapter cable (which is 80% of the maximum capacity, as required by the National Electric Code).

The other short adapter cable with the NEMA 14-50 on one end has an internal resistor with a different value - that is how charger can tell it's a different cable. In principle you can have any number of these short adapter cables, each with a different NEMA plug and each with a different resistor. The Rivian portable charger only has these two short adapter cables and no other short adapter cables are available.

I believe the Tesla charger uses the same or a similar mechanism to determine which short adapter cable is plugged into the charger body. There are no smarts in the process, it's essentially a simple mechanical/passive identification.

And here's the limit of my knowledge: The process I described is correct, but I don't know whether the Rivian charger uses an actual resistor or not - there are many ways to uniquely identify a short adapater cable using only passive components like a resistor, and there are also ways to do this with active components. I know some other brands of charger use a resistor, so I described the Rivian charger as using a resistor - that is probably the cheapest (and therefore most likely) way to do it, but does not preclude some other method. However it's actually done, my original statement in my original post conveys what is happening - "Portable chargers like the Rivian charger "know" which adapter accessory cable is being used".

 

[240vPlug]

Yes, the Rivian charger and also the portable shockflo charger I have read the amperage limit +2 amps.

If you plug in something like the kill a watt you can see exactly what is being pulled. The ShockFlo portable unit shows me the voltage and allows me to adjust amperage right on the mobile charger itself. We love to use that unit at campgrounds. It's always good to see what the voltage drop is on the line and adjust amperage limits accordingly to avoid angry neighbors

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