Newbie Prime owner : what mode to drive in

Discussion in 'Prime Main Forum (2017-Current)' started by harvardMA, Oct 3, 2019.

  1. harvardMA

    harvardMA New Member

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    My first drive to work this morning - it was wonderful ! My drive is about 35 miles - when I picked up the car the guy who showed me the features left it in ECO with EVO set. So it ran down the electric and then switched to hybrid mode. Question is : what should I set this to for the best mpg? Is it possible to answer that or is it dependent on highway vs non, etc?

    thanks
    Ellen
     
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  2. huskers

    huskers Senior Member

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    Congrats on the new car, Primer. Those much smarter will answer your question soon.
     
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  3. mr88cet

    mr88cet Senior Member

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    Reasonable question, and welcome aboard the Prius-Prime “bus”!

    If you don’t want to think about it too much (some people do and some don’t) then the short answer is, “charge when you can, gas up when you have to, and just drive.” It’s a very efficient car and it balances efficiency very well.

    However, it sounds like you do want to put some thought into it. Sooo, question: How are you defining “MPG” in your question?

    Toyota quotes MPG numbers as if charging were zero-cost: If you almost always drive EV, it will report MPG numbers in the thousands. (Well, actually, it’ll cap it at 199.9 or 999.9, depending upon which model-year you have.) So, by that definition, the answer is to always drive in EV mode.

    The other way to define “MPG” is optimal MPG in HV operation. I personally find that definition much more interesting.

    A couple of rules of thumb:
    * EV is better at lower speeds, and HV at higher speeds.
    * If you can do your entire trip on EV, then stay in EV.
     
    #3 mr88cet, Oct 3, 2019
    Last edited: Oct 3, 2019
  4. schja01

    schja01 One of very few in Chicagoland

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    With my few remaining functional brain cells I find it easiest to run HV on clear highways and EV elsewhere.
    ECO 100%.
     
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  5. bisco

    bisco cookie crumbler

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    try ev auto to see how you like it.

    the car defaults to ev when you turn it on, so you have to change it yourself if you want another mode
     
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  6. PT Guy

    PT Guy Senior Member

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    Two unrelated kinds of "mode."
    Eco-Normal-PWR are just the sensitivity of the accelerator pedal. Use whatever feels best to you. We like Normal most of the time and PWR when we're on the freeway and like more scoot to get into a gap in traffic.

    EV-HV-EV Auto are engine and electric operation modes. You're fine keeping it in EV all the time. The system is smart and will use the engine when the battery is depleted, then switch back to EV when it can. I found one route we drive that has some uphill sections, and EV Auto gives a bit lower total gas consumption, 'because it runs the engine on those uphills and saves the battery. Not a big deal. We don't switch to HV at all. Some claim a bit better fuel consumption in some types of driving. So...keep it in EV all the time as you learn about your new car. Later try some other settings and see how they work for you.
     
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  7. johnchang7

    johnchang7 Junior Member

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    I have about a 50 mile commute up and back and I’ve been using EV mode for city driving and then hybrid on freeways. I average about 120 mpg. What you could do is figure out how much EV it takes to get home once you’re exit the freeway. Keep an eye on that and then turn it on when you’ve hit that mark.

    example it takes about 15 miles of EV power to get home once I exit. Ideally it’s empty when I get home or just close to it. But if you do that you should average well over 120 mpg
     
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  8. Salamander_King

    Salamander_King Senior Member

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    Congrats on your new PRIME. If your 35 miles is all on back roads outside of I495, then at least during summer times, you may be able to drive all 35 miles in EV only. If your drive includes highway speed, then try to switch shortly before you get on the highway. Just make sure you give enough time for the engine to complete the warm-up before you really need to push on your pedal to marge. Any side streets or back roads at about 35mph can be done with EV. During summer time, you should be able to get above 199.9 mpg. Sorry, your car has the mpg display up to 999.9mpg, but my 2017 PRIME is limited to 199.9 mpg display, so I don't know how far it goes beyond that.

    During winter is totally different story. If you use your heat heavily, then using HV when you starts your car in the coldest of the morning will help to heat up the cabin fast. Your mpg as well as EV range is likely to drop to almost half of what you have enjoyed during warmer months.

    But for most part, just enjoy. Anyway you drive, it will be highly efficient.
     
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  9. mr88cet

    mr88cet Senior Member

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    Just to make sure there’s no confusion, once the battery is depleted to the HV threshold, it’ll stay in HV mode until you can turn it off and plug it in again.

    Good summary though...
     
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  10. PT Guy

    PT Guy Senior Member

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    Not ours. It runs the engine until it determines that it can run EV for a bit...like a slight downgrade that needs some power and there is some in the battery, then it switches itself back to engine operation when that battery power is gone, then does it again and again.
     
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  11. CraigCSJ

    CraigCSJ Active Member

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    I believe you are describing how HV always works on the Prime.
     
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  12. PianoBench

    PianoBench Member

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    Congrats! I love these type of questions, because it gives us opportunities to share and learn from each other.

    I operate the vehicle like this. I plug-in at home only. My commute is mixed with freeway and city use. Average number of miles a day is 20 to 40 miles.

    Driving:
    1. I drive strictly EV auto or EV Mode in the city always. Until speeds surpass 55 mph.
    2. Before I hit the freeway I will try to switch to Hybrid mode to kick start the engine for warm up. Typically at low speeds 25 mph to 35 mph and definitely when coasting.
    3. If I know the engine is warmed up before hand and I am entering a freeway, I will get up to 55mph speed using purely EV auto and then switch on the hybrid mode after 55 mph. I try to keep my speed under 65 mph. This gets me roughly 65 to 70 mpg on the freeway.
    4. If I get into a slow down on the freeway, I switch to EV auto.

    Charging:
    A. Set the departing charge time to exactly when you will be leaving +/- 15 minutes. This way the battery will never stay at the two extremes. Full charge state or low charge state.
    EXAMPLE: I leave at 8:15 am everyday, so I can set the charge schedule to depart at 8:00 am. By the time I get in the car and unplug, the battery should be at a full charge state.

    Battery Care:
    a. I try to never leave the battery below 20% using the indicator on my dashboard. I understand that the battery keeps itself alive somehow, but that is my limit. I will switch to hybrid mode before it dips under.

    Following these rules I have been able to get about 130 mpge to 105 mpge averages. My overall average is improving as I tinker a bit with my driving habits. On longer trips through the San Francisco Bay area, I can achieve on a single charge maybe 105 to 90 mpge driving mixed for a distance of about 100 miles average.
     
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  13. Curlyone

    Curlyone Member

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    I'm pretty sure you dont have to worry about this. Lots of threads here using math to show the car has a built in limit to keep the SOC in the best range to maintain the battery. When the SOC indicator says 100% that's actually like 80% of what the battery can handle, and when the indicator shows 0% the battery actually has 20% left. (note my numbers may not be exactly right, but it's in the ballpark)

    But these cars are nothing if not flexible, so if it works for you go for it.
     
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  14. noonm

    noonm Senior Member

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    My experience is that the SOC is ~11% to ~82% for the min/max.

    However, it should be noted that this is really a tradeoff. 11-82% is going to wear out the battery faster than say 30-70%, so even limiting the range manually 'could' help. Now, I say 'could' cause SOC range is just one factor for battery degradation (i.e. others are fast charging/discharging, temperature, # of cycles, etc). You can run your battery only between 40-60% SOC and still kill it prematurely by letting it overheat too much.

    Toyota just picked a point that reduces some of the SOC-related battery degradation while still allowing you to use the vast majority (~70%) of the battery capacity.
     
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  15. Hokiehigh

    Hokiehigh Junior Member

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    My preference is Normal mode. It’s already pretty slow in acceleration and ECO makes the car feels borderline dangerous to drive where I live. Plus in Normal mode the car is very efficient.

    agree with most other comments, use hybrid mode on highway and ev for local.
     
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