Charging Efficiency vs voltage

Discussion in 'Prime Plug-in Charging' started by JayGen4, Sep 19, 2020.

  1. JayGen4

    JayGen4 Member

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    For Tesla, I believe using a 120v outlet will cost more, quite a bit more, than a 240v or what not. Something to do with a threshold barely being reached at 120v.

    Does this matter on the Prius?

    Effectively, my question is, does it make any difference in cost to charge with a slower charger? Because it does for Tesla but maybe it's very different for the smaller prius battery that only gets 25mi vs the 320miles of the model 3.
     
  2. Salamander_King

    Salamander_King Senior Member

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    Yes, it does but negligible difference. Not enough to justify buying and installing L2 EVSE just for economical reasons. L1 EVSE 120v @12A will take 6.3-6.7kWh to fully charge the Prime's traction battery after depleting EV range, whereas L2 EVSE 240v @16A will use 5.8-6.2kWh. So on average 0.5kWh/charge more for L1 EVSE. At $0.12/kWh national average cost of electricity, it is $0.06/charge. Even if you do plug-in every day for a full charge, that's only $21.9/yr difference.
     
    #2 Salamander_King, Sep 19, 2020
    Last edited: Sep 19, 2020
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  3. jerrymildred

    jerrymildred Senior Member

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    What @Salamander_King said. (y)

    The small difference is mainly because it takes longer to charge at L1 than at L2, so therefore the cooling fan for the charger plus the control circuitry all run twice as long.
     
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  4. hill

    hill High Fiber Member

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    presuming a 240V receptacle already exists, an install merely requires buying/adding a 240V plug adapter to the vehicle's already existing portable EVSE. You may have the needed Parts in a garage junk door to not even add that very minimal cost. Many on this forum already know, & although it's not acknowledged by Toyota, that portable brick works on both 120 & 240 voltages.

    .
     
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  5. Salamander_King

    Salamander_King Senior Member

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    That presumption is often wrong. In my case, the cost of putting 240v receptacle at where I can charge my car would be a few thousands dollars. Yeah, the OEM L1 adapter to 240V is the least expensive conversion. But I have not seen anyone post the actual kWh using the adapter on OEM L1 to plug into 240v. Is it really close to real L2 @16A? If not, it may take several years to recoup the cost even if it is only $20 for the adapter.
     
  6. jerrymildred

    jerrymildred Senior Member

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    More like L2 at 12A. Plugging the OEM cable into 240V cuts the 120V charging time in half. A full on [email protected] EVSE cuts the time by more than half.
     
  7. Salamander_King

    Salamander_King Senior Member

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    Yeah, I know its 240v @12A, but my question is what the total kWh the OEM cable into 240V will take? I have not read anyone posting their data. I know for L1 in 120v have been reported to take 6.3-6.7kWh to fully charge the Prime's traction battery after depleting EV range, whereas L2 EVSE 240v @16A will use 5.8-6.2kWh. My guess for OEM L1 in 240v @12A would be somewhere in between, like 6.1-6.5kWh. That would make the price difference even less than L1 vs. L2. So the recouping the cost of even $20 for the adapter will take at least a few years.
     
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  8. jerrymildred

    jerrymildred Senior Member

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    Ah! I get it. Thanks for straightening me out. ;)

    One thing that some of us face, though, is quick turnarounds. For example, when I get home at 5:30 today, I need to be ready in about 35-40 minutes to leave for a meeting 20 miles away. Makes a big difference there.
     
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  9. Salamander_King

    Salamander_King Senior Member

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    Yap, that is the major benefit of L2 or OEM L1 in 240v, if your life style requires multiple charges in a single day. For my commuting and car needs, over night charge once a day is all I need. So, only reason I would want the L2 EVSE for my current Prius Prime is the ability to have the charging data via WiFi. But if I ever get my hands on Rav4 Prime or other PHEV or BEV with a larger battery pack, then L2 becomes almost an instant necessity.
     
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  10. hill

    hill High Fiber Member

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    ouch !!
    There is one other solution, should there come a day when you have greater need for 240 charging. Company has been in business for years. Their product is called the "quick 220" .
    You plug the two 110 plugs into sources on opposing sides of the neutral and you get 240 volts outgoing. They're a couple hundred bucks ....
    Quick 220 Systems: Model A220-15D For Equipment with US/Canadian Plugs

    i have had one sitting in thr trunks of different rides now for probably over 7 yrs.
    .
     
  11. john1701a

    john1701a Prius Guru

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    Rebates may not be available then. We got $500 back twice (for two EVSE installs) from our local electricity provider.
     
    #11 john1701a, Sep 23, 2020
    Last edited: Sep 23, 2020
  12. Salamander_King

    Salamander_King Senior Member

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    Thanks. Yeah, @Rob43 told me about the product. Unfortunately, in order to use the gadget successfully, I would have to plug the two ends of 120v male plugs into two separate circuits. That alone is way too much of problem for me. Currently I am using a 120V receptacle that is used in the garage on a 20A circuit. There really is no other receptacle on separate circuit convenient to plug in. And our main panel with only 100A master breaker is completely full with all tandem breakers. So, any expansion will requires either a new main panel or sub-panel which is the part of the 240v installation cost.

    Yeah, probably not. Before jumping to Rav4 PRIME or any other PHEV or BEV, I am likely to invest my money into PV panels on my roof first anyway.
     
  13. jerrymildred

    jerrymildred Senior Member

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    I had the same situation with a full panel. Fortunately, the breaker and wires to my electric water heater were sized for an old one that must have drawn a lot more current. So, I used that 40A breaker to power a small sub panel and fed the water heater and the 240 outlet for my EVSE from a couple 30A breakers in the sub.
     
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  14. Salamander_King

    Salamander_King Senior Member

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    I don't have knowledge and skill level you have, so all the electrical works has to be left to a licensed electrician. I am planning to put PV panel on top of the garage roof, which is detached from the house but is located at much sunnier spot of our yard than our main house. My current plan is to place a sub panel and inverter in the garage that get connected to the PV. All the detail of electrical works will be left for the solar contractor to finish. I just don't feel comfortable to try this project DIY. I am hoping they can somehow make a 50A circuit available in the sub panel to use for 240v plug for EV charging.
     
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  15. jerrymildred

    jerrymildred Senior Member

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    Always wise to recognize your limitations. (y)
     
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  16. Mark57

    Mark57 2021 Tesla Model 3 LR AWD

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    I'm with you. I need to add two NEMA 14-50's in my garage. I know what needs to be done and how to physically do it and how to calculate the correct wire size and type for the run distance, etc. These two connections are going to be pulling serious amps so I'm savvy enough to not use cheap Leviton outlets that like to melt. I'd use Hubbell industrial outlets instead. Even knowing all of that and more, I'm not licensed and I don't want to risk burning the house down because I made a stupid mistake. Yes, I know I could do it, but . . . . . lots of opportunities to get it wrong and only one to get it right.
     
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  17. Salamander_King

    Salamander_King Senior Member

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    On the flip side, any contractor I hire could also make a stupid mistake albeit much less likely than I would. But, in that case at least I have someone else to blame... or sue. I am willing to do a lot of things DIY, provided that saves money and will not endanger my family and others by doing so. High voltage electrical work is not one of them.
     
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  18. Mark57

    Mark57 2021 Tesla Model 3 LR AWD

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    Absolutely. I also like DIY. I worked 30 years around low and VERY, very high voltage and saw what even the lowly 120 vac can do much less the high amp stuff. It's not worth it for me either.
     
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  19. Mark57

    Mark57 2021 Tesla Model 3 LR AWD

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    Do you ever use products like Deoxit DN5?
     
  20. john1701a

    john1701a Prius Guru

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    Contractors here are required to file a permit and have an inspection. So the odds of a mistake should be greatly reduced.

    Back on cost, checked my account for EnelX (JuiceBox). It says my lifetime charging is 4,552 kW. Treating those as all time-of-use discount billed, that would drop the usual 14 cents/kWh to 7 cents/kWh... coming to a savings of roughly $300.
     
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