Rivian Wall Charger oscillates in charging rate, support says normal?

[Gorilla5]

Hi there,

I have a Rivian Wall Charger installed professionally by an electrician with permits. It is a direct connection to my circuit breaker, on a 40amp circuit. Thus the expected continuous output is 32amps, which when multiplied by 240v equates to an expected charge rate of 7.6kw.

I have attached some screenshots of the charging history from my Rivian app. As you can see, the app shows that the charging rate oscillates up and down throughout each session, from a peak of approx 7.6 kw, to around 3-4 kw, and then back to 7.6 kw. Is this normal? Does anyone else have this type of oscillating charging rate? Or are other people seeing a more continuous charging rate (i.e. the histogram stays at 7.6kw or whatever your max rate is, until it hits the target charge capacity?)

The dip switches have been confirmed to be set correctly.

Support is telling me that this is normal so I am checking in with other owners. Appreciate any feedback.

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[boxedlunch]

What does the end of the charging session summary say w/ regard to how much went into the battery vs HVAC?

 

[NY_Rob]

I can't speak for the Rivian EVSE, but I have a JuiceBox Pro EVSE and a Tesla Wall Connector EVSE both on the same circuit with an actual ammeter connected to the circuit. Once charging starts in earnest.. they both charge steady at 32amps till they start to taper off at the very end. No fluctuations or dips in current on either and I use both on my R1T.

 

[Gorilla5]

I can't speak for the Rivian EVSE, but I have a JuiceBox Pro EVSE and a Tesla Wall Connector EVSE both on the same circuit with an actual ammeter connected to the circuit. Once charging starts in earnest.. they both charge steady at 32amps till they start to taper off at the very end. No fluctuations or dips in current on either and I use both on my R1T.

Helpful thanks. I am curious, does your Rivian app show a continuous and level histogram of charging rate?

 

[Gorilla5]

What does the end of the charging session summary say w/ regard to how much went into the battery vs HVAC?

I don't regularly go into the vehicle to check the session summary, as my wife drives the R1T on a daily basis. Instead, I check the Rivian app in the morning and got these screenshots that way. Logically, the Rivian app should show the overall charge rate (i.e. kwh of energy delivered per hour), with the vast majority going into the battery and perhaps a fraction of a kwh going to systems, etc. I can't see 3-4kw of charge being diverted to systems/HVAC, on an oscillating basis, throughout the session?

Thus, I am curious if any other R1T/R1S owners have any screenshots of their charging rate from the Rivian app, so that we can compare apples to apples to see if their charge rates are continuous and linear, or if their charge rates also oscillate up and down when connected to a home Level 2 charger.

 

[NY_Rob]

Helpful thanks. I am curious, does your Rivian app show a continuous and level histogram of charging rate?

I've never looked at the Rivian charge curve on their app before. I just plugged in my R1T and it looks like it's charging steady at 7.0kW...

Below is the charge curve from Saturday via the JuiceBox app. Looks pretty steady at about the same rate of 7.0-7.2kW.

 

[TollKeeper]

My Rivian charger does fluctuate a bit... Nothing like yours thou..

I am also on a 32a circuit. First charge at that amp last night, stayed pretty consistent at 6.9-7.6. Delivered 26 kWh in 2 hours and 35 minutes.

Previously I was on 40a charge, but it burned my wires, but it did the same thing there, fluctuating from 9.2-10.0

 

[NY_Rob]

If you dissect an EVSE.. you will find that it can not vary current as it only has a set of Open or Closed relay contacts. It's either full current flow, or no current flow. The EVSE tells the vehicle how much it can supply based on the EVSE commissioning setup options/circuit breaker size and the vehicle draws current based on the EVSE current limit settings.
Only the vehicle can vary the charge current.

If you're seeing those wild fluctuations it could be the EVSE is overheating/having some sort of other issue and is telling the vehicle to reduce current draw. Could also be something in the vehicle doing it. One way to find out whom is to blame would be to charge your Rivian on some other L2 EVSE and observe the charging curve. Alternately, you could plug a different EV in to your Rivian charger and look at the EVSE graphs.

 

[Magicbus]

I have our Rivian charger directly wired to a 60 amp breaker, DIP switches set to 48 and R1T set to 48. I regularly start off with low amperage, I presume because the air temps have been 30-40F, but then it jumps to over 10KwH and stays there until complete.

 

[COkit]

...
Thus, I am curious if any other R1T/R1S owners have any screenshots of their charging rate from the Rivian app, so that we can compare apples to apples to see if their charge rates are continuous and linear, or if their charge rates also oscillate up and down when connected to a home Level 2 charger.

I also see the fluctuating charge rate using the portable Rivian charger on a 220VAC/32A circuit. I'm curious... when you contacted Service, did they explain why the fluctuation was normal?

 

[Gorilla5]

I've never looked at the Rivian charge curve on their app before. I just plugged in my R1T and it looks like it's charging steady at 7.0kW...

Below is the charge curve from Saturday via the JuiceBox app. Looks pretty steady at about the same rate of 7.0-7.2kW.

I also see the fluctuating charge rate using the portable Rivian charger on a 220VAC/32A circuit. I'm curious... when you contacted Service, did they explain why the fluctuation was normal?

Here is the official response from the Rivian charging team (escalated from Rivian Support to charging team). I must confess I do not really understand what they are saying, the oscillation is due to the vehicle delivering energy after already reaching it's charge limit?... At the same time it's due to colder temperatures? My R1T is kept in a garage.


Correct! I brought this to my team just to make sure that I was interpreting the data correctly. We believe what you are seeing on your mobile app is the vehicle delivering energy after already reaching it's charge limit.

We have seen this happen with our fleet vehicle when charging at lower amperages. The mobile app would show the slight moment it took for the charger to ramp up to it's target amperage, and if it met the charging limit, charging would end, and then resume in that same session when the battery got below that limit.

It also seems fitting due to the colder temperatures that you experience in Vancouver, it is likely that your vehicle is just conditioning the battery, so it is dipping below the charge level and then resuming charging.

If you have any further questions, please don't hesitate to reach out.

 

[SPITmadFIRE]

Here is the official response from the Rivian charging team (escalated from Rivian Support to charging team). I must confess I do not really understand what they are saying, the oscillation is due to the vehicle delivering energy after already reaching it's charge limit?... At the same time it's due to colder temperatures? My R1T is kept in a garage.


Correct! I brought this to my team just to make sure that I was interpreting the data correctly. We believe what you are seeing on your mobile app is the vehicle delivering energy after already reaching it's charge limit.

We have seen this happen with our fleet vehicle when charging at lower amperages. The mobile app would show the slight moment it took for the charger to ramp up to it's target amperage, and if it met the charging limit, charging would end, and then resume in that same session when the battery got below that limit.

It also seems fitting due to the colder temperatures that you experience in Vancouver, it is likely that your vehicle is just conditioning the battery, so it is dipping below the charge level and then resuming charging.

If you have any further questions, please don't hesitate to reach out.

They're saying your vehicle is at the charge limit (I.e. 70% state of charge), and dipping below that limit as it uses energy to condition the battery, or other idle drains like transmitting data over the wire. When the vehicle uses enough energy it tells the charger to deliver some, which the charger does for a brief moment, before telling the charger to stop because it's full again. Essentially oscillating between 69% and 70% in this scenario.

If you plug your vehicle in at 40% or 50%, do you see this same oscillation? If so, I'd tell the service folks their hypothesis doesn't hold water and something is either wrong with your charger, your wiring, or your onboard vehicle charger.

 

[Gorilla5]

They're saying your vehicle is at the charge limit (I.e. 70% state of charge), and dipping below that limit as it uses energy to condition the battery, or other idle drains like transmitting data over the wire. When the vehicle uses enough energy it tells the charger to deliver some, which the charger does for a brief moment, before telling the charger to stop because it's full again. Essentially oscillating between 69% and 70% in this scenario.

If you plug your vehicle in at 40% or 50%, do you see this same oscillation? If so, I'd tell the service folks their hypothesis doesn't hold water and something is either wrong with your charger, your wiring, or your onboard vehicle charger.

Yeah that’s not the case at all. The vehicle is plugged in at 30-40% charge, is set to charge to 70%, and oscillates during charging.

 

[SwaziCAR]

They're saying your vehicle is at the charge limit (I.e. 70% state of charge), and dipping below that limit as it uses energy to condition the battery, or other idle drains like transmitting data over the wire. When the vehicle uses enough energy it tells the charger to deliver some, which the charger does for a brief moment, before telling the charger to stop because it's full again. Essentially oscillating between 69% and 70% in this scenario.

At the risk of confusing things...

The above is how I interpret Rivian's response. That said, when my ChargePoint Home Flex kicks in to "top off" the battery at my pre-set limit (70%), the EVSE pretty much goes directly to the rate it's set for (currently 24 amps, so about 5.76kw), and the resulting charge curve looks like this:

The schedule set for 9:00 pm - 7:00 am. The first gap in the curve is when I've allowed PGE to control the charger from 10 pm - midnight (due to a peak-need event). Then, the EVSE comes back on and completes the charge. In the early morning, after the vehicle has done whatever it does to burn some juice, the flow resumes briefly to get the battery back to 70%, but it does so without obvious oscillation.

This is how the ChargePoint Home Flex works, and I don't know whether the oscillations you're seeing are due just to how things are portrayed in the Rivian app or whether something else is going on.

 

[MidnightRivian]

This is mine while charging using a Rivian charger.

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