Prius Prime: detail about Charge-Mode

Discussion in 'Prime Technical Discussion' started by john1701a, Oct 20, 2018.

  1. john1701a

    john1701a Prius Guru

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    Charge-Mode is a feature Prius Prime offers where the gas-engine can be used to recharge the battery-pack. In most cases, this isn't as efficient of a charging option as just using the plug. But when you are on a road-trip and don't have an outlet available, being able to generate electricity while cruising on the highway can be helpful. That electricity can be used later when you are driving short distances at your destination. That avoidance of engine warm-up is overall beneficial, especially when taking advantage of steady-speed driving to charge.

    Here is a video I created to provide detail about Charge-Mode operation:



    Watch data presented on that phone-app (vertical display on the right) connected to the car using an aftermarket ODB-II reader. It provides detail about power coming from the engine and how much of that is diverted to the generator while charging.
     
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  2. schja01

    schja01 One of very few in Chicagoland

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    Nice info. Useful as per usual.
    Thanks,
    J
     
  3. john1701a

    john1701a Prius Guru

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    It's getting cold here (Minnesota) now. A new use for Charge-Mode came to mind... electricity for warming the cabin.

    If you have the engine running in an efficient manner before parking anyway and you'll be coming out to a cold car later, why not? As the video shows, it would only take a few minutes to generate enough electricity for that.

    The point of Prius is to significantly reduce emissions & consumption, not to eliminate them entirely. That's use of electricity is clearly an improvement over what traditional vehicles do... just run the engine while the vehicle is idle.
     
  4. ziggy29

    ziggy29 Member

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    Neat. I see you got about 38 MPG overall on that trip in charge mode. What would you get in normal HV mode on this trip (i.e. not recharging the battery pack)?
     
  5. john1701a

    john1701a Prius Guru

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    It would be upper 50's for the drive in those conditions. Warmer and without that crazy wind, it there's potential for around 60 MPG.

    I tried a similar drive a few weeks ago, but consumed the electricity generated afterward. The result was mid 50's. So no matter how you drive it, Prime still competes with the best of them of overall emissions & efficiency... and excels at flexibility.
     
  6. triggerhappy007

    triggerhappy007 Active Member

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    Can we calculate the efficiency of the video?

    Seems like John used a little over a gallon of gas to drive 39 miles. At the end, it added 22 miles of electric range. So that's about 60 MPG, about the same if he didn't use charge mode. That's really good efficiency then or is my math off?
     
  7. schja01

    schja01 One of very few in Chicagoland

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    Just completed my first trip. A modest 150 mile. 75% flat 25% rolling hills.
    EV auto until EV depleted then charge mode then EV auto again then Charge Mode.
    Averaged 50 mpg.
    I’m happy with that.
    Return trip will be HV mode.

    Question: Charge mode only charged to 80%.
    Please confirm that it’s working as designed.
    It wouldn’t let me select charge mode until the battery was 80% or less. Correct?

    J
     
  8. john1701a

    john1701a Prius Guru

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    Yes, 80% is the upper limit for Charge-Mode.

    Of course, you could "stack" generate to get it higher. That's what owners did with the previous generation. You put it in EV mode just prior to slowing down. Coming off of a highway, you can collect quite a bit for use as EV later.
     
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  9. Tideland Prius

    Tideland Prius Moderator of the North
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    50mpg seems a bit low for that kind of terrain; but I guess I don't know what kind of speeds you were doing.

    Averaging 35mph, I can get 60mpg or better on flat+rolling terrain with P&G on the Gen 4. Also, with the larger battery, the Prime should do better.

    Would be curious to see how you fare in just HV mode on the return trip.
     
  10. rhkennerly

    rhkennerly Junior Member

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    I’m a new prime owner. I don’t remember anything in the manual about charge mode.

    Did I miss something or is this an aftermarket mod?
     
  11. dchasse

    dchasse New Member

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    I'm a new owner also just having my Prime Premium for 3 weeks now. I asked my salesperson if there was a way to charge the traction battery while drive and they were not sure. I found out about the charge mode by reading the manual. To get into charge mode you just press and hold the EV button for about a second and a EV charge mode light will appear on the display indicating that you are in that mode. Just press again to exit or just shut off the car and it will revert back to EV mode on next start up.

    I've used it myself when the opportunity to charge via plugin was not available. It works as advertised.

    Really enjoying the car so far and love the EV mode of driving.
     
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  12. Old Bear

    Old Bear Senior Member

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    It's controlled by the EV/HV mode button on the console to the right of the shift lever. When in "charge mode", the gasoline-powered internal combustion engine ("ICE") will bring the traction battery charge up to 80%, at which point the Prime automatically will return to HV mode. From the owners' manual:
    Prius-Prime-charge-mode.jpg

    This feature exists because some cities in Europe and elsewhere restrict downtown access to zero-emission vehicles at particular times. Using charge mode, it is possible to recharge the traction battery during a normal trip into the city so that there is sufficient charge available for EV operation once one arrives at downtown. (I have used it just because I prefer EV driving in city traffic.)

    Although Charge Mode can be used at any speed or even while "idling", it appears to operate most efficiently when cruising at speeds between 35 mph and 45 mph. I believe that this is because the ICE has the capacity to both propel the vehicle and provide power to generate electricity. Even so, the basic laws of physics still prevail and the power needed to generate electricity will result somewhat in a reduction of your gas mileage (mpg.)
     
  13. rhkennerly

    rhkennerly Junior Member

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    Thx for the reply but now i’m really confused.

    This is a problem throughout the manual.

    There are three batteries, right? The 12 volt starting battery, the ice/hybrid traction battery & the battery you charge with an electric cord, which us also a traction battery.

    The manual is very loosely throwing around the term “hybrid battery (traction battery).”

    I can’t figure out if, from these directions, if by performing this action I am recharging the plug-in traction battery or the hybrid / ice traction battery, or both.

    Doesn’t the hybrid/ice traction battery recharge automatically while driving anyway?

    Does this switching of modes actually recharge the plug-in traction battery using the ice? (A feature I thought was put off until 2019).

    Any light you could shed would be appreciated.
     
  14. schja01

    schja01 One of very few in Chicagoland

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    Return trip in pure HV mode.
    This time rolling hills first with cooler temps and flatland a bit warmer. 33F / 55F respectively.
    155.4 total miles portal to portal 54.3 mpg 3hrs ET.
    J
     
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  15. Tideland Prius

    Tideland Prius Moderator of the North
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    There's only two batteries - your regular 12V car battery that you're familiar with, and the larger hybrid battery (also called the traction battery).

    The hybrid battery is the one you charge (either engine or via your power outlet/electric cord). This is the battery you use to power the vehicle in EV mode. When you brake lightly and are under regenerative braking, the car is charging this same battery.

    You can charge the hybrid battery on the fly with the engine using the charge mode ("CHG" mode). You have to press and hold the "HV/EV" button you access that mode.
     
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  16. rhkennerly

    rhkennerly Junior Member

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    Thx for setting me straight. But i’m still confused.

    So I now have to manually switch to charge the traction battery? In my 2006, charging is managed automatically, charging or using the battery as a supplement to the ice.

    Or, is just a portion of the battery used like a traditional Prius, and any additional charging of the battery has to be switched manually?
     
  17. jerrymildred

    jerrymildred Senior Member

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    Some quality time with the manual will clear up 99% of your confusion. ;) In short, you don't have to manually do anything but open the door, get in, start it, put it in gear, and drive it like any other car. You CAN manually put it into charge mode to add charge to the traction battery while driving, if you want to. You can also do lots and lots of other things with it. But all you really have to do is just drive it. It's a fantastic car. If you thought your 2006 was smart, you ain't seen nothin' yet. Your new car is a genius. (y)
     
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  18. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    There are only some relatively rare special situations for which the "Charge" mode makes economic sense. Coming off of extended highway driving and wanting some battery charge for subsequent EV city driving is one of them. But that is entirely up to you. In general the expected scenario with respect to charging the battery is that you plug it in to charge it whenever you want to, and the car will use the battery when there is charge in it, and operate in ordinary hybrid mode with gasoline like a regular Prius if the charge is used up. As mentioned by jerrymildred, you really don't have to anything other than keep enough gasoline in it to operate it like a regular Prius, and plug it in whenever/if you want to get some EV driving. You don't have to switch anything; it just works.
     
    #18 CharlesH, Oct 26, 2018
    Last edited: Oct 26, 2018
  19. Tideland Prius

    Tideland Prius Moderator of the North
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    Jerry and Charles have excellent replies (see previous two replies).


    But you bought a plug-in hybrid right? A Prius Prime? If you don't plug it in at home, then you will be driving the Prime like your 2006 Prius.

    The "CHG" function is optional and it's basically there for you to choose if you wanted to top up a battery while driving so that you have enough charge to cruise around in electric mode when you reach your destination town/city. You can go your entire ownership cycle with the Prius Prime and not use the CHG function if you so wish.
     
  20. Prodigyplace

    Prodigyplace Senior Member

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    Perhaps they really wanted the black grille missing on the Liftback Prius. :confused::LOL::ROFLMAO::sick:
     
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