Hybrid vs EV mode

Discussion in 'Prime Technical Discussion' started by Pizza Driver, Oct 17, 2016.

  1. Pizza Driver

    Pizza Driver Active Member

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    Some questions on the Hybrid mode compared to the EV.

    From what I understand the Chevy Volt has a "hold" mode that forces the use of the ICE rather than draining the battery, allowing the car to maintain its current EV range until the "hold" mode is turned off.

    Is the Hybrid mode on the Prime similar?
    Or does it change the car into the kind of hybrid operation as you would get in the non-plugin Prius?
    If the latter, does the Hybrid mode take into account the current state of the battery and try to reserve that portion for pure-EV mode?
    In a mix of in-town and hwy driving for a 80 mile trip, when would EV mode be better and when would Hybrid mode be better? (as an example, consider the following trip: in-town 10 miles; hwy 10 miles; in-town 40 miles; hwy 10 miles; in-town 10 miles)
     
  2. mmmodem

    mmmodem Taste Tester

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    In HV mode, the PiP stops using your remaining EV miles. Initially, when you activate HV mode, some of that EV distance will be used up to allow the engine to warm up. I was told it will eventually regen the used EV distance. I rarely switch to HV long enough to allow the used EV to come back.

    EV is most efficient at low speeds, below ~46 mph. So you would keep it in EV until you get on the highway.
     
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  3. Trollbait

    Trollbait It's a D&D thing

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    The Volt hold and Prime hybrid mode are the same thing. In them, the car stops using grid electric from the battery, and starts up the ICE for running as a hybrid, like they would do when the grid charge is used up.

    If the trip is going to exceed the EV range, better to use the ICE on the highway, and save the electricity for lower speed portions.
     
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  4. Tideland Prius

    Tideland Prius Moderator of the North
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    Our understand is that HV mode is similar to the HOLD mode in the Volt (and other PHEVs). It will function like a regular Prius.


    In your example, I would probably do...

    EV, HV (or CHG depending on how much left), EV Auto, CHG, EV until it runs out (the car will go into HV mode when the chargeable portion is out)

    assuming you can't charge the car during your "in-town" segments.


    Alternatively, you can sacrifice the first segment and go

    HV, HV, EV Auto, CHG, EV.
     
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  5. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    I will have the opportunity to fully charge once, perhaps twice per week. My round-trip commute is just over 50 miles.

    My plan is to drive my commute in HV mode because the ICE has time to warm up and I can be good enough mileage. I'll use EV driving for shorter trips around town (gym, library, errands) when the ICE wouldn't otherwise have a chance to warm up. Basically, eliminate those otherwise MPG-killing short trips.

    Should we ever move and get a 2-car garage, I'll charge each night and use the EV for the morning commute.
     
  6. Mister MMT

    Mister MMT Active Member

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    Driving a Prime will differ quite a bit of driving a PIP:

    Jan
     
  7. Fred_H

    Fred_H Misoversimplifier

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    Generally, it is best (most efficient, convenifortable and economical) to drive the whole trip in "EV Auto" mode. Most of the time the Prius knows better, thinks faster, and is less lazy when deciding to switch back and forth between modes.

    The exception is when you can predict the future better than your Prius. Then you can strategically deplete, save, or charge, so that the rest of the time, the Prius has enough SOC leeway to freely chose the momentary optimum propulsion mix.
     
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  8. giora

    giora Senior Member

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    Prime's Charge Mode is new unknown to me with respect to rate of charge, MPG hit etc. I need to experience it before recommending (to myself) in various situations of well known trips.
    Just thinking: when HV cruising at 70-75 mph flat land, it could be that with force charge the engine thermal efficiency will be a better than without!
     
    #8 giora, Oct 18, 2016
    Last edited: Oct 18, 2016
  9. Fred_H

    Fred_H Misoversimplifier

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    If the efficiency curve is still much like the Gen 3 Prius, then maybe rather at 70-75 km/h:

    [​IMG]
    (thanks Bob Wilson)
     
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  10. GasperG

    GasperG Senior Member

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    Under load ICE efficiency won't be much different with CHG mode or without, the main question is wether you use that charge more wisely than ICE later in your drive. eg. siting in city traffic with AC on.

    If we look at EPA rating for EVs, typically city MPG is 20% higher than highway, Prius gets 8% better MPG in the city. Maybe EV mode will be much more efficient than hybrid mode. The problem is that you have to charge battery exactly as much as you will need later, because if you park and charge with SOC left then you have made a dumm thing.
     
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  11. giora

    giora Senior Member

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    Could be, the message is that at low loads, CHG mode can increase thermal efficiency of the engine.

    Not sure I caught your message. Prime expected EPA is 133 MPGe on EV, 54 MPG HV combined, 55 MPG city.
    As to not force charge more than needed for the trip, yes and can be done on familiar trips.
    This reminds me of tactics I am using sometimes with my PiP on trips, to reserve some EV for return trip - only to find out I can charge at destination...
     
    #11 giora, Oct 18, 2016
    Last edited: Oct 18, 2016
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  12. Trollbait

    Trollbait It's a D&D thing

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    Why couldn't you use an exterior EVSE? I know the installation cost will be higher if you have to run lines to a free standing one.

    The engine efficiency could be better, but the vehicle efficiency still drops. The limited reports has that dropping from the 50's to the 40's in MPG. Outside of charge mode, there could still be times when the car can turn the ICE off, even at highway speeds. I've seen it on a gen2, and the later gens can use electric at higher speeds.
     
  13. giora

    giora Senior Member

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    You are stating the obvious, let me try another phrase:
    Situations where engine efficiency rises will make smaller drop of vehicle efficiency, will you agree to that or maybe "on the other hand" is something you cannot resist?:eek:
     
    #13 giora, Oct 18, 2016
    Last edited: Oct 18, 2016
  14. Trollbait

    Trollbait It's a D&D thing

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    Never claimed it wouldn't lessen the vehicle efficiency drop, just reminding readers that it doesn't negate it.

    EV operation is more efficient than ICE. Going 20 miles in hybrid mode will take about 36% of a gallon of gasoline. The kWh to go the same distance in EV mode is equal to about 15% of a gallon. The unknown is what the charging losses of charge mode are. The likely hood is that they are worse than charging from the wall. So if a misjudgement is made, and Charge mode electric is still in the battery when the car is plugged in, some gasoline was wasted by staying in Charge mode too long, or not going into EV mode soon enough.

    For the majority, using EV Auto will likely yield better overall fuel economy than trying to juggle EV, Hybrid, and Charge mode when driving past the EV range.
     
  15. fotomoto

    fotomoto Senior Member

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    Can't run an extension to the OEM 120v EVSE at your parking spot? Lots of folks do this and leave the EVSE in the car while charging for security. The door gaskets have enough give to not harm the cable.
     
  16. Pizza Driver

    Pizza Driver Active Member

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    Help me understand why hiway driving does not naturally restore a good deal of the battery charge.

    Currently, when I watch the energy monitor in my Prius C traveling at 65 mph it shows the ICE powering the wheels and sending current to the battery. Every once in a while the battery will send a current to the motor for a very short time, but mostly the ICE is sending a charge to the battery. So wouldn't hiway driving naturally tend to charge the battery?
     
  17. Lee Jay

    Lee Jay Senior Member

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    Because that bit going to the battery is to run accessories like the power steering and the electronics. If it was always charging it would eventually overcharge on a long trip. Even the Prime in CHG (Charge) mode will eventually stop charging the battery once it gets to 80%. I would expect to see charge still flowing out of the generator toward the battery after that time to run accessories just as it is now on the regular hybrid Prius.
     
  18. giora

    giora Senior Member

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    But this fact was mentioned in the post you quoted...

    The fact you can decide when to choose CHG mode is an advantage - choose it at low load sections and you minimize the MPG hit.
     
    #18 giora, Oct 18, 2016
    Last edited: Oct 18, 2016
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  19. Trollbait

    Trollbait It's a D&D thing

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    It is minimized, but that doesn't mean it is minimized enough to be worth the effort to do so.

    There is still unknowns about the car's operation for us, but when we learned about charge mode, it was mentioned that it was intended for restoring charge for when the destination bans ICE use. Then there isn't a blatant Charge mode button. Only those that read the manual, or visit sites like Priuschat will even know there is a Charge mode.

    If using Charge mode outside a few specific situations can increase overall vehicle efficiency, then it will happen automatically in EV Auto.
     
  20. Prius Maximus

    Prius Maximus Senior Member

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    Now I'm confused. in My Gen 2 and Gen 3 regular hybrid, in stop and go traffic my battery runs down to the point the ICE fires and runs to charge the battery. After the battery receives a minimal charge sufficient for hybrid operation, it will go back to running in "electric" mode until the battery runs down again. Rinse and repeat. Once I get out of stop and go traffic and up to speed, the ICE runs, and the battery charges. Long before I get off the highway, the battery is fully charged (to 80% or whatever). It seems obvious to me that the ICE recharges the battery and does more than just power accessories when it's running.
     
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