L2 Charger Fluctuating Power Level

[tjrivian]

I've noticed that recently the Power Level of my L2 charger(240V, 20A circuit, limited to 16A due to 80% debate) is fluctuating during charging. Electrafi screen shot below. My other vehicle(a Jeep PHEV) doesn't seem to have this power fluctuation. Any idea what could be causing this on the Rivian?

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[HaveBlue]

You may be having a voltage drop that the car is sensing and then backing off to 12A. The drops from 3.8kw to low 3s seem to indicate that. I'd check wiring connections from the bus bar to the EVSE including grounds and neutrals.

 

[tjrivian]

I agree with you that the drops from 3.8kW to low 3s could be from voltage drop. But what I'm really concerned about are the drops all the way down to 1.7kW. It's hard to believe that voltage drop could be causing that, the car would have to be backing off all the way to 7A.

Would be nice if Rivian would report both voltage and current over their APIs instead of just power.

 

[HaveBlue]

The J1772 communication standard using resistance values generally does 12,16,24,32,40,48,(56,64)and 80A. The car can elect to draw less or more if it chooses to ignore that but realize that 1.7kW isn't necessarily 7A. You may be dropping a leg with a bad connection and only be getting 140V @12A. That means heat somewhere when the car (or more likley charger) senses something bad at 16A it drops to 12A and still has an undervolt.

 

[tjrivian]

I was able to catch it today during the time it was at a reduced power level. The screen on the charger said it was only putting out 7.6A, 240V. The screen on the charger also said that it's temperature was 84C when it started to throttle back, and around 70C when it increased the power again. So seems like something is causing the charger to get quite warm and it's thermally throttling to protect itself.

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