Varying charge rate from same public ChargePoint station

Discussion in 'Prime Plug-in Charging' started by BettyW, Feb 20, 2020.

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  1. BettyW

    BettyW New Member

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    I’ve had my 2020 Prime since Monday. :) I’m trying to understand its charging behavior. I have used the same ChargePoint station located in a basement parking garage twice this week with significant difference in the amount of charge received for an identical charge period:

    - day 1 charge was 3.71 kWh; day 2 was 1.86 kWh
    - Both were same time of day 4:30pm-5:40pm
    - same ChargePoint charger (one of two); day 1 a Tesla docked at 2nd charger for 15 min, day 2 I didn’t see anyone else
    - car had been parked outdoors for 8 hrs prior after being driven 8 miles; then half mile to charger.
    - day 1 outside temperature was mid-high 30s F; day 2 was high 20s-low 30s
    - day 1 car had about 20% charge to start; day 2 had 4%
    - between day 1 and 2 I temporarily lowered the car’s charge rate from Max to 8A while trying to debug a home gfci breaker tripping with level 1 charger, but I reset that before visiting the station on day 2.

    Does the battery being only about an average 7-10F colder all day make that much of a difference? Or is it the battery being almost out? Or more likely random power fluctuation of the charge station (it’s free so can’t complain)?

    I plan to install a home level 2, but currently am dependent on public charging.
     
  2. Rob43

    Rob43 Senior Member

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    Congrats & welcome to PriusChat !

    *************************************

    Do you currently have any type of 240 volt outlet near your prime ?

    If you do, you can charge up at home in about 2:28 minutes for less than $50 dollars.


    Rob43
     
  3. jerrymildred

    jerrymildred Senior Member

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    If I interpret this right, both days it was plugged in for one hour and 10 minutes to an L2 system. From fully depleted to full is just over 6 kWh and take 1:50 on L2. Rounding it off, that's just over three kWh of charge per hour. It would give you close to four kWh over that time if there was room for it. Was there room for it? You didn't mention the state of charge of your battery when you plugged it in. Not having room for more charge is the best explanation I can think of. I'd guess that on day 1 the state of charge was close to zero and on day 2 it was closer to 50%.

    The test would be if the battery was full when you unplugged both times. If it was not full on day 2, then perhaps someone interrupted the charging.
     
  4. BettyW

    BettyW New Member

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    As I said, day 1 battery started with 24%, day 2 with 4%. So in neither case did the battery come anywhere near full. On day 1 I received 3.71 kWH in 70 minutes; on day 2 received only 1.86 kWh in 70 minutes.
    Not yet -but my electrician is desperate for work next week so he will be by :) Anyway, I'm more interested in the "why" of different charging rates at the same station than in the "how to make it better there".
     
    #4 BettyW, Feb 21, 2020
    Last edited by a moderator: Feb 21, 2020
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  5. Rob43

    Rob43 Senior Member

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    1) Chalk it up to a fluke. It's not your personal charging equipment, so you just don't know. If it was a L1 or L2 at your home with a history of working a certain way, then everyone could give better ideas.

    2) Install a NEMA 14-50R, it's a solid choice for Future Proofing your 240 volt needs. Then use your Toyota OE EVSE at 240v for quick 2:28 minute charging.


    Rob43
     
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  6. m8547

    m8547 Active Member

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    Some Chargepoint charger are like that. There's one I used to use at work that would randomly reduce the charging rate. I thought it was something weird about the car. But they put some new ones in, and now it pretty much always charges at 3.3kw. Some of them have a feature where only a total of 6.6kw is available to the charger, so if there are two cars they will limit it to 3.3kw each. But that shouldn't affect us. I think they also have a feature where they can coordinate with other electrical loads in a building, but I'm not sure.
     
  7. jerrymildred

    jerrymildred Senior Member

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    Sorry. I missed that. Yeah, I'd blame the Charge Point gear. I hear a lot about how flakey it is. I've used a couple and they were flakey, too.
     
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