Roller Coaster Charging Rate - Fast, Slow, Fast Slow, Fast??

[HokieR1T]

10k miles on my R1T, but still very much new to EV's.

I had an interesting charging experience today at an EA station. (8 stations, only one other occupied, I was using a 350 kWh). The rate started well, around ~205 the first few minutes, then quickly dropped to mid 30's, and as quickly as it dropped, went back to ~205. a few minutes later, it did the same, and one more quick drop and rise back to ~170 kWh. Overall 53 kWh added in 18 minutes, so I would take the total charge every time, (esp EA popped up "Free" at the end). Similar experience at the same station a few weeks ago, but different charger. And only one sudden drop and rise that time.

Is this common? What could be causes?

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[gorwell]

Pretty standard for rivian and others based on conditions.

Most likely the battery was getting too hot so rivian backed off the power to allow itself to cool.

 

[atebit]

There’s no indication that the truck’s throttling the charge rate because of battery overheating? Seems like there should be.

 

[HokieR1T]

There’s no indication that the truck’s throttling the charge rate because of battery overheating? Seems like there should be.

There was the message that the rate was slower due to the station throttling the rate, but the sudden dip and rise lasted no more than 30-45 seconds.

 

[jjwolf120]

It could be thermal issues with either the station or the truck. It also might the result of "software features" of either or both.

 

[electruck]

There was the message that the rate was slower due to the station throttling the rate, but the sudden dip and rise lasted no more than 30-45 seconds.

The EA unit's cooling system or temp sensor was on the fritz causing it to throttle down and then back up. This is also why you got a free charging session. Don't think EA would give freebies if the problem were the vehicle.

 

[HokieR1T]

It could be thermal issues with either the station or the truck. It also might the result of "software features" of either or both.

That has me intrigued.

Background I should have included on the original message. Yesterday morning and again yesterday at lunch, a brief message popped up upon putting my truck in reverse - "DC Fast Charging Performance Reduced Service Soon" I called the service line and they said they would look in to it and call me back, the usual. Still waiting. The message hasn't appeared since. The sole reason I went to to this charger was to test the truck. Thus the choice for the 350 kWh. I'm curious if the two are related. But once again. 53 kWh over 18 min is a better than average charge.

 

[jakef801]

I have the Rivian wall charger, but horsed around with the 120v to help comment on another thread based on whether or not latest OTA improved 120/240 efficiency. It was 103F in the shade and it barely took a charge in 10 hrs. I would post the log if the app actually saved it. All in all, I think I gained 16 miles / 3ish% (70% to 73%). Basically a waste of time. Locked doors, no AC, vehicle quiet. Made me a believer that climate is and will be coming into play, hot or cold, in charging. I'm charging to 100% tonight at 48amp, which has been giving me about 11kwh, as I'm driving to Bear Lake tomorrow. First semi-big road trip and going to launch a 25' boat (not towing, boat is already up there). To be continued...

 

[electruck]

It's also entirely possible that both the vehicle and charger were experiencing problems. Other than acknowledging that one or more things were not working like they should have, it would take Rivian and EA engineers to fully explain what was happening in your specific situation. Regardless, that was not normal charging behavior. Common is a different matter as some will tell you that it is common to have problems charging with EA.

 

[ATL_R1S]

The EA unit's cooling system or temp sensor was on the fritz causing it to throttle down and then back up. This is also why you got a free charging session. Don't think EA would give freebies if the problem were the vehicle.

This is my bet. EA's cable cooling has been very inconsistent and will aggressively throttle down when the temp sensors get hot. I highly doubt it was the car having an issue. In the majority of cases, it's always EA's shitty, unreliable equipment and cable cooling that either doesn't work correctly or simply can't take the heat of high powered charging in a particular environment.

 

[Dark-Fx]

That has me intrigued.

Background I should have included on the original message. Yesterday morning and again yesterday at lunch, a brief message popped up upon putting my truck in reverse - "DC Fast Charging Performance Reduced Service Soon" I called the service line and they said they would look in to it and call me back, the usual. Still waiting. The message hasn't appeared since. The sole reason I went to to this charger was to test the truck. Thus the choice for the 350 kWh. I'm curious if the two are related. But once again. 53 kWh over 18 min is a better than average charge.

I just got this message after going from hard acceleration to full regen getting onto the freeway to do a turnaround. Haven't DC charged in over a month.

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