Max current draw when charging at 240v appears to be 15a

Discussion in 'Prime Plug-in Charging' started by ihf, Jan 2, 2022.

  1. ihf

    ihf New Member

    Joined:
    Sep 7, 2021
    18
    0
    0
    Location:
    NJ
    Vehicle:
    2022 Prius PHV
    Model:
    LE
    I am charging my 2022 Prius Prime using a 240v, 30a rated circuit and I have the line monitored at the panel. What I am seeing is a max of 3600w which would mean that it doesn't draw more than 15a (I have verified that my supply voltage is 240v), The car's documentation says that it should draw 16a (which would mean ~3800w). Has anyone else measured the power utilization?
     
  2. john1701a

    john1701a Prius Guru

    Joined:
    Jan 6, 2004
    12,473
    5,081
    57
    Location:
    Minnesota
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    The highest draw I have seen from mine is 15.4 amps at 242 volts. That was 3.73 kW. An expectation of 3.6 kW is what I normally see and what I would state to others as a reasonable maximum.
     
    #2 john1701a, Jan 2, 2022
    Last edited: Jan 2, 2022
    Henrik Helmers and ihf like this.
  3. john1701a

    john1701a Prius Guru

    Joined:
    Jan 6, 2004
    12,473
    5,081
    57
    Location:
    Minnesota
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    Here's that info from my JuiceBox. Notice it is the initial spike. Speed slows down a bit after charging settles. Screenshot_20210728-005411_EV%20JuiceNet.jpg
     
  4. ihf

    ihf New Member

    Joined:
    Sep 7, 2021
    18
    0
    0
    Location:
    NJ
    Vehicle:
    2022 Prius PHV
    Model:
    LE
    I just charged the battery from a fully depleted state. I thought that the battery capacity was 8.8KWH and that EV mode accounted for 80% of that (7 KWH) but my monitor says that charging was completed (in 2 hrs) with 6.67KWh. Here is the graph:
    Does this seem right and is it consistent with what others have seen?
     
  5. john1701a

    john1701a Prius Guru

    Joined:
    Jan 6, 2004
    12,473
    5,081
    57
    Location:
    Minnesota
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    It is, but no plug-in vehicle uses its entire capacity. A buffer is reserved at both ends for longevity. In the case of PHEV, there is a reserve for hybrid driving as well. For EV driving, the SOC ranges from roughly 12% to 84%. That means there is really only about 6.3 kWh that you'd replenish from a "full" recharge.
     
    jerrymildred likes this.
  6. jerrymildred

    jerrymildred Senior Member

    Joined:
    Oct 28, 2016
    11,199
    13,656
    0
    Location:
    Tampa, FL
    Vehicle:
    2017 Prius
    Model:
    Two
    Looks great. Toyota will not let you charge to an actual 100% SOC nor will it let you go down to zero. That would just kill the battery's lifespan.

    I don't have the actual numbers memorized and don't have time to look them up now, but indicated 100% is actually about 83% and depleted is in the teens which can go a little lower in HV mode after depletion.

    And I see that @john1701a just beat me to it. LOL!
     
    john1701a likes this.
  7. ihf

    ihf New Member

    Joined:
    Sep 7, 2021
    18
    0
    0
    Location:
    NJ
    Vehicle:
    2022 Prius PHV
    Model:
    LE
    Correction. Fully recharging the battery after the car had switched to HV mode, used 6.24KWH
     
  8. jerrymildred

    jerrymildred Senior Member

    Joined:
    Oct 28, 2016
    11,199
    13,656
    0
    Location:
    Tampa, FL
    Vehicle:
    2017 Prius
    Model:
    Two
    That can vary quite a bit because the SOC while in HV with a depleted EV range can vary quite a bit even though there is very little movement on the battery gauge due to its scale.
     
  9. fuzzy1

    fuzzy1 Senior Member

    Joined:
    Feb 26, 2009
    16,322
    9,476
    90
    Location:
    Western Washington
    Vehicle:
    2012 Prius
    Model:
    Three
    If the charging operation has a fixed power limit, then it will reach maximum current only when the line voltage is at the lower end of its tolerance range, something below 230V.
     
  10. ihf

    ihf New Member

    Joined:
    Sep 7, 2021
    18
    0
    0
    Location:
    NJ
    Vehicle:
    2022 Prius PHV
    Model:
    LE
    If I understand you correctly, the amount of battery capacity that the car reserves for HV mode can vary. In particular, the 20% of 8.8KWh (~1.8KWh) may sometimes be greater (or I suppose less). In my case, it would appear to be ~2.5KWh. What exactly determines these variations?
     
  11. john1701a

    john1701a Prius Guru

    Joined:
    Jan 6, 2004
    12,473
    5,081
    57
    Location:
    Minnesota
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    HV level naturally varies. Sometimes it is low. Sometimes regen is so high, you recover a little bit of EV range.
     
  12. jerrymildred

    jerrymildred Senior Member

    Joined:
    Oct 28, 2016
    11,199
    13,656
    0
    Location:
    Tampa, FL
    Vehicle:
    2017 Prius
    Model:
    Two
    Just as the battery SOC varies as you drive a regular Prius, it varies when driving a Prime in hybrid mode. When it gets too low, the car charges it back up.
     
  13. ihf

    ihf New Member

    Joined:
    Sep 7, 2021
    18
    0
    0
    Location:
    NJ
    Vehicle:
    2022 Prius PHV
    Model:
    LE
    I understand that the HV varies as the car is driven (and recharged thru regenerative braking). What I am not completely clear about is how the battery capacity used for EV would vary. That is, in order to assure the maximum EV range (~25mi) I thought that 7KWh (80% of the 8.8KWh traction battery) was reserved for EV mode. Yet, when I recharged the battery from a depleted state (the EV portion) it drew only 6.24 KWH. It is not a big deal, just trying to understand how this works.
     
  14. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,615
    8,507
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    The amount you use for a full charge varies from session to session for various reasons. The 12v battery charging system, the battery heater operating, battery cooler operating, climate-preconditioning operating all use more kWh. This time of year, the traction battery heater is the main cause of variation if you live in colder climate. See my data below, Dec charge (kWh) was 7.22kWh per full charge compared to 6.6-6.8kWh during earlier months.

    For L1 EVSE, 6.5-6.8kWh is the average full charge. For L2 EVSE, 6.0-6.3kWh is the average full charge. Either way, the portion used by EV mode is ~5.5 kWh.

    Monthly average kWh used for a full charge by L1EVSE
    upload_2022-1-3_9-44-32.png
     
    #14 Salamander_King, Jan 3, 2022
    Last edited: Jan 3, 2022
  15. ihf

    ihf New Member

    Joined:
    Sep 7, 2021
    18
    0
    0
    Location:
    NJ
    Vehicle:
    2022 Prius PHV
    Model:
    LE
    Interesting. Why would the KWh vary depending on whether L1 or L2 EVSE? Shouldn't it be the same amount of energy regardless of the charging voltage?
     
  16. Ovation

    Ovation Active Member

    Joined:
    May 11, 2021
    156
    129
    0
    Location:
    Quebec
    Vehicle:
    2021 Prius Prime
    Model:
    Base
    I believe it has to do with higher efficiency of thicker gauge cabling but I’m sure one of the much more knowledgeable electricians will offer a more complete answer soon.
     
  17. john1701a

    john1701a Prius Guru

    Joined:
    Jan 6, 2004
    12,473
    5,081
    57
    Location:
    Minnesota
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    Higher voltage is more efficient. That's why the big transmission lines run at 22,000 volts and is reduced at distribution points.
     
    Ovation and jerrymildred like this.
  18. Salamander_King

    Salamander_King Senior Member

    Joined:
    Nov 8, 2015
    10,615
    8,507
    0
    Location:
    New England
    Vehicle:
    Other Hybrid
    Model:
    N/A
    I am not an engineer, but some people have commented that in addition to the higher efficiency of 240V, L2 EVSE takes a shorter time (almost 1/3 of L1) to finish the full charging, thus shorter times to run the traction battery cooling fans and other components of the battery management system all of which uses kWh to run.
     
    #18 Salamander_King, Jan 3, 2022
    Last edited: Jan 3, 2022
    jerrymildred likes this.
  19. jerrymildred

    jerrymildred Senior Member

    Joined:
    Oct 28, 2016
    11,199
    13,656
    0
    Location:
    Tampa, FL
    Vehicle:
    2017 Prius
    Model:
    Two
    This.^^^

    A small amount of the difference is thanks to higher voltages incurring less of a voltage drop, less heat generated and wasted for the same amount of power, etc. But a big factor is that at L2 you run the cooling fan on the charger, the charger itself with its inherent losses, and the computers, for less than half the time which cuts that electrical overheard in half.
     
    fuzzy1, Ovation and Salamander_King like this.
  20. fuzzy1

    fuzzy1 Senior Member

    Joined:
    Feb 26, 2009
    16,322
    9,476
    90
    Location:
    Western Washington
    Vehicle:
    2012 Prius
    Model:
    Three
    Big transmission lines use high voltage to reduce electrical resistance losses, also known in the industry as I-squared-R losses (current * current * resistance, the formula for wire heating). For a given amount of loss, higher voltage reduces the cost of the wire.

    As Jerry already pointed out, while this is a factor in L1 vs L2 efficiency, it probably isn't the largest issue.
     
    jerrymildred likes this.
Loading...