Rivian AC charging curve is weird. Why?

[mpshizzle]

I've noticed that Rivians (I've seen this with 3 vehicles now so I know it's not an anomaly with a single vehicle) have a very unstable charging rate on AC.

I've had extensive experience with Ford EVs and Tesla and they charge a pretty stable rates. Rivian on the other hand is all over the place. When set to 48 amps, it VERY loosely is kinda somewhere around 10.7Kw ish. But not stable at all

Totally not of consequence but curious if anyone has thoughts as to why it does that

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[Mathme]

I wonder if it other cars average the charge rate where Rivian may show the actual charge rate.

....that's just a guess...

 

[MountainBikeDude]

What you're outlining there is the issue I've been having with my Rivian and my LED lighting in my house. The draw seems to be inconsistent with the Rivian causing my downstairs lighting to dim and brighten enough to be like a candle flickering in the wind. The general theory is that when the Rivian is converting AC-DC it's not fully stable? and also backfeeds noise into the power supply.

 

[LindaI]

Interesting observation. I work as a power electronics engineer, and it is likely that the charger inside the vehicle has a power factor correction front end, that might be slightly unstable, but clearly meets the definition of good enough. The PFC and power conversion could be done with a DSP or microcontroller with a lower than ideal (but good enough) sample rate. Not something of concern, but it would be interesting to see why it happens.

 

[Marchin_MTB]

I've noticed that Rivians (I've seen this with 3 vehicles now so I know it's not an anomaly with a single vehicle) have a very unstable charging rate on AC.

I've had extensive experience with Ford EVs and Tesla and they charge a pretty stable rates. Rivian on the other hand is all over the place. When set to 48 amps, it VERY loosely is kinda somewhere around 10.7Kw ish. But not stable at all

Totally not of consequence but curious if anyone has thoughts as to why it does that

Do you get similar amounts of variability if you lower the charge rate to, say 28A.

 

[mpshizzle]

I wonder if it other cars average the charge rate where Rivian may show the actual charge rate.

....that's just a guess...

This is data coming from my EVSE so it's the same reporting for all vehicles

What you're outlining there is the issue I've been having with my Rivian and my LED lighting in my house. The draw seems to be inconsistent with the Rivian causing my downstairs lighting to dim and brighten enough to be like a candle flickering in the wind. The general theory is that when the Rivian is converting AC-DC it's not fully stable? and also backfeeds noise into the power supply.

Interesting you should mention that. My home is newly built with entirely LED lighting and I haven't had any issues. But I have a buddy with a Rivian who lives in a home built in the 70s with much older wiring and he has reported similar flickering issues

Interesting observation. I work as a power electronics engineer, and it is likely that the charger inside the vehicle has a power factor correction front end, that might be slightly unstable, but clearly meets the definition of good enough. The PFC and power conversion could be done with a DSP or microcontroller with a lower than ideal (but good enough) sample rate. Not something of concern, but it would be interesting to see why it happens.

Interesting that would make sense to me. Curious that's something they'd cheap out on. I wonder if any other auto makers have done the same.

Do you get similar amounts of variability if you lower the charge rate to, say 28A.

Decided to try it at a lower amp last night.. this time 21 and.... Interestingly it IS smoother. Not 100% flat, but no cars charging rate is perfectly flat. But it is substantially more stable. Curious indeed

 

[MountainBikeDude]

Interesting you should mention that. My home is newly built with entirely LED lighting and I haven't had any issues. But I have a buddy with a Rivian who lives in a home built in the 70s with much older wiring and he has reported similar flickering issues

It's kinda funny, my house was built in the 70's but we had all the electrical pulled and redone 3 years ago when we purchased the house.

 

[HaveBlue]

I have pretty healthy voltage drop only charging at 40a 9kw. Some outlets drop to 108v from about 117v. I never see more than 235v on the main and things get warm.

 

[Count Orlok]

an artifact of how the display of data is programmed. Edward Tufte would be pleased.

 

[Dark-Fx]

Useless to have power without voltage and current graphed also.

 

[Tango45]

an artifact of how the display of data is programmed. Edward Tufte would be pleased.

Perhaps this would be better represented in a pie chart... or several of them. /s


I Tufte

 

[mpshizzle]

@Dark-Fx
Don't call me useless!! ?

 

[DeafPug]

Maybe they’ve changed it, but my OpenEVSE unit didn’t really measure the voltage. They just had 120/240 Volts hard-coded in the source code. This was on a unit I purchased about 7 years ago. It looks like your OpenEVSE unit is doing the same.

 

[mpshizzle]

Maybe they’ve changed it, but my OpenEVSE unit didn’t really measure the voltage. They just had 120/240 Volts hard-coded in the source code. This was on a unit I purchased about 7 years ago. It looks like your OpenEVSE unit is doing the same.

Voltage is generally very stable at my house, but not completely unchanging haha. I believe you're correct.. but even that being the case, the current the Rivian is drawing is highly unstable in comparison to the Tesla that charged just before

 

[Glembi2]

Perhaps this would be better represented in a pie chart... or several of them. /s


I Tufte

Something like this?

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