Charging Mode Efficiency

Discussion in 'Prime Fuel Economy & EV Range' started by dogbohn, Mar 5, 2018.

  1. dogbohn

    dogbohn Junior Member

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    Am wondering when there might be an overall mileage benefit from charging mode. Of course, using charging mode will drop mpg. What I am wondering is, under what circumstances might there be a net gain, so that your mileage in the EV mode would be greater than the miles lost in Charging mode due to decreased mpg. My instinct is that at low speeds, it is better to simply remain in hybrid mode when there is not enough charge to do EV mode. I am wondering about highway speeds, wondering if the decrease in mpg would be so small that it would be worth it to use charging mode on the highway. OTOH, there must always be a loss in the conversions and this might be trying to get something for nothing and going into perpetual motion machine thinking.
    Anyone know for sure if/when charging mode can be a net gain?
    Thanks.
     
  2. ct89

    ct89 Active Member

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    Any time you convert energy from one form to another, you waste some. Running the engine to charge the battery to then later run the car is less efficient than running the engine to run the car...UNLESS, when you run the engine to charge you would otherwise be operating very inefficiently and can actually get ahead and when you run with those stored electrons, you do better enough to overcome the inefficiencies. Some of the conversations here about warm-up cycles point to cases where the ICE might be operating and you have a chance to extract power pretty efficiently.

    I've been intrigued by the experiments people have run with highway driving...How much does it cost to charge over HV mode and is that a win later. I wish there was a way to modulate the charging load. I often take longer highway trips. If the car knew this and was able to charge such that I reached full battery upon arrival, I suspect it could be more efficient than current charge mode behavior.
     
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  3. Wuzki

    Wuzki Member

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    It’s matter of how you want your prime!
    Mpeg vs mpg ? Who will win?:LOL:
     
  4. michael byrne

    michael byrne New Member

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    IMG_6754-2.jpeg Use Charge mode only on steep upgrades and make sure you will have a long enough ramp to get the ICE warm ( pun intended). The ICE mpg is really bad on steep hills, so a few extra watts sent to your battery will not kill your ICE mpg. Once the ICE is warm, it avoids the warmup when it is reengaged. I have a 104 mile roundtrip to the office. Using the charge mode on steephills - I have two on the way in and two in the way out. Blew past my own personal mpg records using this method today. The car is only a month old, but I have over 420,000 miles of Prius driving under my belt from two previous Prius' ( a 2006 and a 2012). You can see I did a little worse on the return, but that always happens for me since I live on a mountain ridge. Fully charge on the way in and fully charged on the way home. You also have the added benefit of having warm ICE, so when you electric mileage remaining goes to zero, the ICE will not automatically kick in if you have just a mile or so to go and you go easy on the accelerator. On a equivalent cost basis , for me, ymmv due to differences between what we pay for electric and gas, this works out to ~95 mpg. Includes $.8 charging at home and $1.20 charging at work,, My gas here is $2.82/gal.
     
    #4 michael byrne, Apr 12, 2018
    Last edited: Apr 12, 2018
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  5. michael byrne

    michael byrne New Member

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    Also , the astute observer will note I use the power mode ( the red background behind the mpg). After driving the two Hybrid Prius for 12 years and over 420,000 miles, I have developed a very light touch on the accelerator. The system coaching feedback I was getting from Prius Prime was to accelerate faster. So rather than try to retrain the muscle memory in my foot, I just switched to Power mode full time which does the same thing.
     
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  6. breakfast

    breakfast Active Member

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    That's really impressive. My best MPG on a 50 mile interstate drive (door to door) with a full battery is a (still impressive) 151.4 on a nice spring day, which is roughly equivalent to 30 miles of EV driving and 20 miles of HV at 60 MPG :) ). That's without CHG mode.

    Nice to see that you are using CHG mode to great advantage to get your 199.9 average over 50 miles :)
     
  7. Darken

    Darken Active Member

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    I'm not sure which is more impressive: the fact that you get such great mileage on your 100+ mile round trip commute, or the fact that you actually make that kind commute regularly! :eek:

    With those numbers charge mode may be worth looking into under certain conditions. Have a long trip to TN coming up in a few weeks and was trying to determine if its worth trying charge mode on the 400+ miles of highway driving.
     
  8. breakfast

    breakfast Active Member

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    I actually beat that today with 164 MPG on a 50 mile interstate drive with a full battery, without charge mode
     
  9. mad-dog-one

    mad-dog-one Prius Enthusiast

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    Wouldn’t the MPG be lower if you had used charge mode.
     
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