Tesla Universal EVSE Connected, but 12V battery drained

Discussion in 'Clarity' started by Demian Johnston, Oct 16, 2023.

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  1. Alex800st

    Alex800st Active Member

    I’d guess you got two issues. 4A load it’s like one halogen bulb, and it should not drop the voltage to below 10v in a matter of minutes.
    and your evse is definitely behaving in a strange way. I would try it with another (normal) car. Does it work ok with tesla?
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  3. The second chart shows that the Tesla Connector was draining the fully charged 12V battery for a total of approximately 5 hours. A brief load was also applied when the Emporia device was connected. The sudden drop over the last 30 minutes or so occurred after the battery had been under load for about 4.5 hours.
  4. MrFixit

    MrFixit Well-Known Member

    @Demian Johnston

    Nice job collecting data while trying to diagnose this issue...

    It is indeed baffling as to how it would be possible for the EVSE's to behave differently (given the very limited functionality of the J1772 interface). And, even if they do behave differently in some obscure way, how could this impact the 12V battery drain like you are seeing?

    When the EVSE is connected to the vehicle, but NOT charging, the pilot signal should be a 1 KHz square wave who's duty cycle informs the vehicle of the current capacity of the EVSE. It seems like this should be identical with either EVSE.

    While thinking about this, I ran into this post on Reddit:

    Although not complaining of LV battery drain, this person was experiencing constant clicking / cycling of some sort, which he felt was the relay within the EVSE, turning the AC line on and off every few seconds.

    At the end of the reddit thread, he reported that he contacted Tesla, and this problem was resolved by installing a firmware update (23.8.2/20230310). Perhaps Tesla does have a fix that might somehow relate to your unusual issue.

    I also agree with the general feeling that your 12V battery is probably toast at this point.
    Demian Johnston likes this.
  5. Alex800st

    Alex800st Active Member

    Would be interesting to try that tesla evse on another clarity, or at least on any other ev
  6. Does a Model Y qualify as any other EV?
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  8. Alex800st

    Alex800st Active Member

    I guess, kinda :)
    If you can put an amp clamp on 12v battery
  9. Alex, you are misreading the data I previously showed. The 5 minute drop was after hours of drain…

  10. Thanks for the link. I do have the latest Wall Connector Firmware

    What I notice is a cycle of about 1 minute. In fact, it is so close to one minute that I suspect it’s a timer. The EVSE (tesla universal wall Adapter makes a relay clicking sound) and the clarity begins a cycle of a variety of noises that sound like smaller relays, and perhaps temp control systems. At the beginning of this cycle, the green charging port light blinks for about 15 seconds and then turns off. At the very end of this cycle, the amp draw drops to negligible levels for a few seconds before it begins again.

    To be clear, this cycle ONLY occurs when the Clarity’s HV battery is fully charged and the Clarity remains connected to the TESLA Universal Wall Connector.

    I did engage with level 1 Tesla Support via chat (despite emailing many of the support related email addresses). Chat Support’s suggestion so far is “Contact Honda”).

  11. My hypothesis is that the Tesla EVSE is “offering charge” in a very different way than my Emporia EVSE. If the EVSE itself is going through a 1 minute cycle of some sort, could it be that this “1 kHz square wave pilot” is being interrupted and the clarity’s system basically think the cable is being unplugged and replugged in once every minute?
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  13. Have you connected the Tesla device to the Clarity when the HV battery is less than fully charged and charging has been programmed to begin a few hours later? I’m only asking because I haven’t seen where you’ve mentioned that specific situation.
  14. Apparently the Chatbot has never attempted to “Contact Honda”. It also doesn’t realize the Clarity, for the most part, has no issues with any other L2 device. Maybe your case will be elevated to the next level so that you can speak to a human in a foreign country who has no idea what you’re talking about.
  15. Good suggestions, and here's some interesting observations:

    There are 2 different ways in which the vehicle could be programmed to charge later with the Tesla EVSE: 1) Honda's scheduled charging and 2) The Tesla Universal Wall Connectors scheduled charging.

    In BOTH cases, while the Car is awaiting the start of charging, it is exhibiting the 3.5-4A draw I previously described.

    According the IOS "Wall Monitor" App which uses the Tesla Wall Connector API the Wall Connector is in "Status: Negotiating" when the Tesla App is configured for future charging. And when the Honda is scheduled for future Charging, the EVSE alternatives between "Status: Negotiating" and "Status Charge Fully Charged" (as if the Honda is "telling" the evse that it is full until the schedule start time passes).

    My conclusion is that the "negotiating state" on the EVSE is what is causing the power draw on the Clarity's 12V system.
  16. Thanks for the explanation. Technically, only one method involves programming the vehicle while the other involves programming the EVSE. Both, however, create the same condition and produce the same result. That being, with the Tesla EVSE connected and a depleted HV battery awaiting a charge, a load is applied to the 12V battery until HV charging begins. From your previous tests we know that the Tesla EVSE continues to place a load on the 12V battery after HV charging is complete.

    If I’m following along here, it appears as though the Tesla EVSE places a load on the 12V battery whenever it is connected to the Clarity and not actively charging the HV battery.
  17. Alex800st

    Alex800st Active Member

    OP, any news on the issue?
  18. alexsahka

    alexsahka New Member

    When I first installed the Tesla Universal Wall Connector, I didn't notice any unusual behavior while charging my Honda Clarity. However, upon completion of the charging cycle, the Tesla Universal Wall Connector contactor began engaging repeatedly at one-minute intervals. I contacted Tesla support, and they provided a replacement Tesla Universal EVSE unit. Upon receiving the replacement unit, I discovered that it was completely unresponsive, displaying a constant green light when connected to my Honda Clarity. The vehicle's charging status remained stuck at "disconnected" and failed to transition to "connected" (blue light). I contacted Tesla support once more, and they performed a firmware update. The replacement unit subsequently commenced charging, but it exhibited the same behavior as the previous Tesla Universal Wall Connector, initiating contactor cycles every minute after completing the charging process. I suspect that these repeated contactor cycles are placing an unnecessary load on the 12V battery due to the constant vehicle wake-up cycles.

    Both my Honda Claritys exhibit the same behavior of the contactor closing and opening every minute after completing the charging cycle, while my Tesla Model 3 charges normally without any issues. As an electrical engineer, I find this behavior concerning and have resorted to disabling charging from the Tesla app until a resolution is found.
  19. Keanen

    Keanen Member

    Until yesterday, I've only had Juicebox chargers at home and a lake property. I setup two new universal chargers yesterday and woke up to a dead vehicle. I found this thread and am disappointed I may not be able to use my new chargers with my car :(

    Thank you all for sharing your experiences. I wonder if Honda would ever update their software to accept the Tesla chargers and not deplete the 12v battery!?
  20. insightman

    insightman Well-Known Member Subscriber

    I doubt Honda has a staff of programmers working on Clarity PHEV software updates. It's only the Tesla EVSE that kills the Clarity; perhaps it's not adhering to the same standards all other EVSE makers observe.
    MrFixit likes this.
  21. MrFixit

    MrFixit Well-Known Member

    Since we have never heard of any Clarity charging issues with a non-Tesla (J1772) EVSE, I think it is clear that the problem here lies with Tesla Wall Connectors and it is not a Honda issue...
  22. Tesla would be the favored player in that fantasy league.

    There were some issues with a certain L2 device that seemed to afflict only the 2018 models and, if I recall, Honda issued a software update to resolve that problem. I wouldn’t hold my breath waiting for Honda to fix an incompatibility issue with a Tesla device.

    Here’s a preview of Honda’s solution:
    “We recommend that only Honda approved equipment be used with your Honda vehicle.”
  23. Alex800st

    Alex800st Active Member

    What if Clarities that had that issue with Tesla evse - all 2018, unpatched? I have 2020, but no tesla charger, would be interesting to try.

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