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Will EVSE Overload Vehicle Acceptance Rate

Discussion in 'Clarity' started by Steven B, Apr 16, 2023.

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  1. Apr 16, 2023 #1
    Steven B

    Steven B Active Member

    This was a Rivian-sponsored charger at a TN state park. I previously charged at this location in January (I do not remember what power delivery rate the EVSE reported then). Yesterday, I started the charge and about 15 minutes in, the charge stopped. I knew the car was not full, so I checked the EVSE display and initiated charging again via the fob.

    Just like the initial charge 15 minutes earlier, the EVSE display reported that it was sending 7.2kW to the car. After the charge stopped immediately this time, I disconnected the cable and reconnected it. The Clarity's charge port light was fast-blinking (while disconnected and connected) and charge initiation via the fob would not work. I got in and powered up the car and the display reported "charge system malfunction, vehicle power degraded" or something similar. I moved the car to a different parking spot and did an overnight backpack.

    Today, back at the car, when powered up, the check engine light was on but there were no charge system warnings. Not wanting to press my luck, I didn't try to charge there again.

    I power cycled the car and the CEL remained. We headed home but stopped for lunch after about 40 miles in HV mode. Likely after starting up for the final leg after lunch, the CEL was gone. I failed to notice when we left the lunch spot but noticed about 10 minutes later.

    Other bits of data:
    1) 2018 Car has 68k with slightly more than half estimated in EV.
    2) I primarily charge on 120V with maybe 50 partial charges on L2 since Dec 2017.
    3) I had driven mainly in HV mode getting to this destination but switched to EV for last ~4 miles. Ambient temp 70F.
    4) Battery was at approx 60% SOC.
    5) I do not have an OBD2 scanner to check the error log (Question: will the recommended model for reading battery capacity also read all DTC error codes for the Clarity?)
    6) My phone (and possibly the TCU) had no cell coverage at this location, so I could not confirm how much charge the car took. 15 minutes would have been about 10% but I did not note the specific number of charge bars on the vehicle display. During that time, it did sound like it was charging.

    Since there isn't an 8% efficiency loss in a new charge cable (I believe I was the first person to use this EVSE in January), was the EVSE really sending 7.2kW to the car even though the car should have told it to only send 6.6 kW?
     
    Last edited: Apr 16, 2023

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  2. Apr 16, 2023 #2
    JFon101231

    JFon101231 Active Member

    I'm under the impression the car "pulls" juice, therefore it can't overcharge itself using too high of a rate etc.
     
  3. Apr 17, 2023 #3
    MrFixit

    MrFixit Well-Known Member

    Maryland
    I have seen some inconsistencies in the reported capacity of the charger in the Clarity. It is my belief (and my experience) that the capacity is 7.2 kW (30A @ 240V). As such, I believe the 7.2 kW is "correct" And yes, it is not the EVSE that 'pushes' energy, it is the vehicle that 'pulls' it, so the vehicle should protect itself and an over current condition should not be possible.

    There was a technical service bulletin (TSB 18-097, attached) issued in 2018 that related to problems with poor or fluctuating power from certain EVSE's. This was not a 'recall' and dealers would install this TSB on-demand if a customer was having trouble. I don't know if that could have been your issue or not.
     

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  4. Apr 17, 2023 #4
    Landshark

    Landshark Well-Known Member

    Oregon 2019 Touring PHEV
    To answer your title question, No. The EVSE is a fancy extension cord that also allows 2-way communication between the power source and the vehicle. It is designed to protect the power source from the vehicle.

    Typically, a L2 EVSE will be on a dedicated circuit that is protected by a 50A breaker, which is rated to continuously power a 40A load. Any vehicle equipped with an onboard charger that is rated at 9.6kW or less, will be able to charge at the chargers maximum rated capacity. A charger cannot charge at a rate higher than its maximum capacity, even though the available source of electricity has capacity to spare.

    To the question quoted above, I’ve seen what appears to be official Honda documents that specify the charger as 6.6kW/32A. The issue there, is that 32A is closer to 7.7kW. I have a “dumb” L2 EVSE, plug it in and walk away. Until I installed a home energy monitor last month the load of the charger was unknown. It appears to be very close to the 6.6kW figure.

    In your case, what may have occurred was a communication error. This happened early on to some owners, and may have been specific to the 2018MY. As I recall, Honda issued a fix. You also have a CEL to track down.
     

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