Prime - Charge Mode Experiment

Discussion in 'Prime Fuel Economy & EV Range' started by Optimus PRIME, Jan 12, 2018.

  1. Optimus PRIME

    Optimus PRIME Active Member

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    Had a long drive home tonight and noticed that my gas tank was getting pretty low, at about 1 bar left. I had 29 miles to go with lots of hills, and the computer shows 47 miles left on gas.

    Decided to use the Charge Mode, my 2nd time using it, to see how much I can get on EV before my gas tank runs dry. It took a little over 30 minutes to charge to 80%, and by the time I got home, I had 5 miles left on Gas, and 23.8 miles left on EV with 84% charge.

    It was a cool experiment for me, as I was able to build up that 80% charge for just in case I needed that extra 20+ miles to get to a gas station.

    So here are my two thoughts:

    1. How many of you have used Charge Mode? And does anyone know how much gas and how efficient is it to convert from gas to electric using this method? Obviously, for me it was less than ideal since I was driving through hills, so I wonder how ideal it would be on relatively flat roads.

    2. I was wondering ... my current average mileage is about 650 miles for full gas/battery and I charge every night to the fullest and try to maximize my EV usage whenever possible by switching between EV/Auto/HV modes manually. But what if I start driving FULL using EV/Auto, and then engage the Charge Mode to build it back up to 80% and then go EV/Auto again, and repeat this process over and over. I wonder how much mileage we can get using this method? Has anyone tried this?

    Thanks in advance.
     
  2. Tideland Prius

    Tideland Prius Moderator of the North
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    Calling @bwilson4web and @Charged Up . They've both done experiments and have documented it.

    Also, here's a challenge if you want a target to aim for. He did use the CHG mode during the trip. Note the lower speeds (so no highway speeds)

     
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  3. JamesBurke

    JamesBurke Senior Member

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    @bwilson4web suggested using charge mode to convert your last bit of gas to electric as part of his run it out of gas tests. If you have charge you can use the heat pump, keep your cell charged, get news from the radio run an inverter off the hybrid battery ect. Don't remember the ICE restart procedure if you really did run it out of gas.

    @john1701a did some charge mode test on his interstate drive to Wyoming. Recall it was about the same mpg as hybrid mode driving at those speeds overall but again you end up with ev range/charge that might have other benefits in a given circumstance.

    Still better to plugin if you can. Somebody will point out that you might have switched to EV when you had charged enough to get you home instead of all the way to 80% but you were just doing an overall test.
     
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  4. bwilson4web

    bwilson4web i3 and Prime

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    If not perfect, close enough. When the low gas light comes on, you have about 1 gallon of gas remaining. This is more than enough to put an 80% charge on the battery which becomes the "reserve" range. The electric metrics for miles remaining is so much more accurate than the gas 'guess-o-meter' that you can handle the last miles sensibly.
    Sad to say, possible does not mean practical. Our Prime engine at 40% efficiency, similar to current thermal generators, is still saddled with expensive fuel, gasoline. Coal, nuclear, and renewables are so cheap that getting the energy from the grid (with the exception Boston or a Blink charger) is cheaper, half the price per mile. The perfect profile is:
    1. Drive EV from the charger until done when the car switches to hybrid.
    2. Drive in hybrid until the low fuel light comes on and switch to CHARGE mode.
    3. Drive until the gas engine stops and the car is in EV mode by monitoring the SOC or EV miles remaining.
    4. Use the last reserve to reach a charger or motel or gas station or safe place to wait while AAA to brings gas.
    Bob Wilson
     
  5. Stever56

    Stever56 New Member

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    I will use the charger when I'm running down hills that are somewhat steep. Running charger on flat get you 40mpg approx

    Posted via the PriusChat mobile app.
     
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  6. Andyprius1

    Andyprius1 Senior Member

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    I generally use ICE charge to get the car up 3 large hills and recharge to the bottom of the American River Canyon. Now begins another hill climb and hopefully enough charge to make it home in EV. Mild Winter here, so home charge is only 22-24 miles. Vs in Summer 30 miles. I want to see if i can get 1000 miles on a tank. It looks like no problem thus far. My daily trips include freeways at 55mph, 50% and mountainous, also about 50%.
     
  7. Optimus PRIME

    Optimus PRIME Active Member

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    Thanks everyone
     
  8. PIPlook

    PIPlook New Member

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    Just curious - what is the current mpg indicated while driving in charge mode? I assume this varies with speed.
     
  9. Andyprius1

    Andyprius1 Senior Member

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    The mpg is still displayed in the same place, it should increase slowly, or decrease depending o load, weather, temps, etc.
     
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  10. PIPlook

    PIPlook New Member

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    Sorry I should have clarified the question. While in charge mode does the prime indicate less mpg? I was guessing it would since energy was being expended to charge the traction battery.
     
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  11. Andyprius1

    Andyprius1 Senior Member

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    It can and does, with a big load, ie: hills. If one likes to accelerate up hills, that is not conducive to conservative driving, nor is accelerating downhill. The brakes are regenerative so the best action is to lightly ride the brakes, The driver determines gas mileage. Learn the car and cooperate with it, it will amaze you. This is my 4th Prius now since 2005.

    Agree, Iv decided if I have run out of EV and the engine is running, I may as well put it in Charge, for the next hill, UP.
     
    #11 Andyprius1, Jan 30, 2018
    Last edited by a moderator: Jan 31, 2018
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  12. vvillovv

    vvillovv Active Member

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    I've run in charge mode 4 or 5 times so far. First time was real cold, maybe 10 F and snowing.
    I drove about 20 miles at around 35 mph and got to 80% full or 20 miles EV, than topped it off at a Level 2 while I got my mile walk exercise for the day. Final charge showed 27 - 28 EV miles.
    Second time I fell asleep before plugging in at home, when I woke up there wasn't enough time for a full charge on Level 1. It was cold that day too. I started the ice an let her idle through her warmup cycle and started off in charge mode. I went about 10 miles at 35 mph and added 10 EV miles, plugged in and finished charging at level 1 and finished on time.
    Third time was the high speed test. It was warmer. a bit above freezing and mostly 55 mph. I used EV mode twice and charge mode twice on a 60 mile trip. I could feel MG1 and it felt like I was driving with B mode engaged. I needed EV miles when I got home and I was looking at about 22 EV miles available and about 45 mpg for the trip.
    But it only took two more days of full charge EV trips to bring that 45 mpg back above 100 mpg.
    The other time or two I only vaguely remember.
     
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  13. Andyprius1

    Andyprius1 Senior Member

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    Fascinating!
     
  14. vvillovv

    vvillovv Active Member

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    The stock gauges in Prime plus for mpg (topping at 199mpg ) is not as granular as the PIP mpg gauge was ( topping at 999.9 mpg ).
    Thus the drivers ability to compute efficiencies for things like differences in slope / elevation changes, charge mode mpg, EV mode are less accurate. But the lower mpg rate of the Prime probably reduces "range anxiety" because when dropping from EV mode to HV mode after EV range is used up and the ICE switches on the 199.9 mpg stays showing on the dash for a much longer time than the 999.9 mpg stays showing on the dash (after the ICE comes on ) with the PIP.
    Just another reason I would enjoy some of the features available with the premium and advanced.
    I just noticed this behavior this morning while driving 29 miles EV, than the ICE came on for about 6/10s of a mile after which the dash still showed 199.9 mpg and 29 miles driven. I charged at a level 2 charger and had 28.2 estimated EV after 2 hours and 12 minutes. 34 F Heat pump on all the way - mistakenly forgot to take it out of B mode for about 11 miles, guessing where I might have forgotten,- cause I typically do those switches automatically.
     
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  15. inferno

    inferno Senior Member

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    Running charge mode diwnhill doesn't seem to help.... At least in the winter. It looks like it only turns on the engine as your car will recharge normally with the tires rotating. Don't know why this is but I think the pack is not at the optimal temperature to take advantage of the charge... I have also tested this in b mode on ev. Car changes to b mode on hv in the winter as engine turns on.
     
  16. vvillovv

    vvillovv Active Member

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    The prime is still much like an enigma to many previous prius owners. It has a steep leaning curve even from previous PIP owners/leasee like myself.
    It's no mystery to me how mysteriously the primes behavior can be sometimes.....

    Charge mode will not do anything if treated like a strict hyperlinking ( get more efficiency from the hybrid system )
    technique except lower fuel economy.
    Don't get me wrong, there are ways to use charge mode that will produce better results than switching it on at 65 mph.

    It is also a feature that can be used to get the EV section of the primed traction pack recharged
    ( to 80% or so of what the plug will charge the traction pack to, at any given point ),
    when the prime system refuses to charge the traction pack above the HV traction pack range,
    which is that part of the traction pack that is used by the prime when EV range runs out and the ICE starts up.
     
    #16 vvillovv, Feb 26, 2018
    Last edited: Feb 26, 2018
  17. Insighter

    Insighter Member

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    Hi Bob - I suppose others have weighed in on this elsewhere, but I think there are almost 1.5 to 2 gallons remaining when the low gas light comes on. It came on for me the first time last night as I was exiting the freeway. I drove one mile to a gas station and filled my Prime up for the first time. It took 9.54 gallons for me to fill the tank completely (too completely, unfortunately, as I overfilled it a bit and a bit spilled out). The manual lists the Prime's fuel capacity as 11.4 gallons. Perhaps it's a bit more with the filler neck filled like I did, but it couldn't be much more. So I believe the Prime has at least 1.6 gallons left when the low fuel light first comes on.
     
    #17 Insighter, Mar 9, 2018
    Last edited by a moderator: Mar 9, 2018
  18. michael byrne

    michael byrne New Member

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    My $.02 ..one you have drive of more than 35 miles, you want to end your trip with a fully discharged battery. My secret formula, of trips longer than 50 miles, ICE mode going up hills, EV auto mode on the flats with speed over 60. Any flat with a speed of around 45 is the sweet zone. I always try to save EV mode for those sections ( if you know your route). Never use ICE going downhill, that is not productive, EV auto or straight EV are best for downhill. Free wheeling ( gliding with no electric charge or usage) is the most efficient method but that is much harder in the Prime than in an older Prius ( throwing into neutral is not recommended for safety reasons, but if you press the gas pedal with t right touch it is also possible in the Prime).
    Over 400,000 miles with two Prius' now working on a third with a Prius Prime. Now into the 10th day with nearly 1000 miles..
    [​IMG]
     
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