Will the EV-Auto mode drain the battery all the way down if you drive far enough ?

Discussion in 'Prime Fuel Economy & EV Range' started by GKL, Jun 13, 2020.

  1. GKL

    GKL Active Member

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    This is our first week with our 2020 Prius Prime XLE, normally when we stay in town (small town) we can keep it in EV mode.

    My wife had to travel out of town (likely about 40 miles each way) so I told her to put it in EV-Auto mode so it would switch between EV and Hybrid mode on it's own.

    I am assuming she did that and didn't leave it in EV mode (I have to ask her when she wakes up to be sure).

    I just checked the battery and it was completely drained of the EV part, I tried putting it in EV-Auto and it said it was not available due to low battery.

    I plugged it in to charge and it gave the full time needed to charge - 5 hours and 50 minutes.

    Is it normal for the EV-Auto mode to let the battery get that low if you drive it far enough ?

    Would we have needed to use the HV mode to keep that from happening ?

    If it's normal and EV-Auto gives better overall mileage, that's fine, as long as I know it's normal for the EV-Auto mode to drain all the EV capability if driven far enough.

    I'm a noob at this if it sounds like a pretty basic question :D
     
  2. schja01

    schja01 One of very few in Chicagoland

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    Yep. EV/HV Auto in my experience is almost the same as EV only a little more aggressive in the use of HV for heavy acceleration. Both EV and EV/HV auto will deplete the EV portion of the traction battery. When that happens both will operate as in HV mode eg. act as a traditional Prius until the traction battery in charged via regen braking or downhill coasting.
     
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  3. Salamander_King

    Salamander_King Senior Member

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    As said above, EV Auto basically behaves like EV mode. It stays EV mode until the EV portion of the battery is depleted and then change to HV mode. EV Auto is useless mode for most people who drives conservatively. The only time the engine will kick in and change to HV is when you floor the pedal on quick and aggressive acceleration. My driving situation almost never calls for such aggressive acceleration.
     
  4. GKL

    GKL Active Member

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    Thanks both of you !

    We drive conservatively, usually the only quick acceleration is on an on ramp getting on an expressway or passing a slow car.

    So the rare times we do go out of town where we would exceed the 25 miles available in EV mode, is the HV mode preferable over the EV-Auto mode, or should we just leave it in EV mode and use up the battery and let it switch to HV at that time ?

    Maybe start out in EV mode until we reach the expressway then switch to HV mode for the expressway speed driving ?

    Just trying to figure out what works best to get the best overall mileage and still be the best way to drive the car.

    Again, normally we only use EV mode when staying in town, it is a small town and we can usually do all our running and get back home before 25 miles is reached for the day.
     
  5. Salamander_King

    Salamander_King Senior Member

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    Normally, EV on in-city stop and go traffic, and HV on highway speed works to be the most efficient. You can experiment with it to suit your driving preference and resulting mpg and miles/kWh. But just driving till EV runs out is the easiest way to drive and that's what my wife does. When I drive, I usually switch EV and HV manually depending on the driving distance and terrain. I try to use HV on acceleration and uphill, and save the EV on flat or downhill coasting. If the distance is substantially longer than the EV range (about 80 miles), you can get both good mpg and miles/kWh.
     
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  6. schja01

    schja01 One of very few in Chicagoland

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    As my sig. says.
     
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  7. GKL

    GKL Active Member

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    Sounds logical, thanks for the ideas !

    :LOL: I've heard some of us plug-in hybrid owners tend to overthink some things :LOL:

    As a noob to having one I guess I just want to get a pretty good understanding :rolleyes: :LOL:
     
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  8. Tideland Prius

    Tideland Prius Moderator of the North
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    Congrats on finally getting your Prime!!

    Yes that’s normal. I find EV Auto acts like EV mode unless you preemptively switch to HV mode, let the engine do its warm up cycle then switch back to EV Auto. In that scenario, I find the engine comes on more often than if you didn’t warm up the engine (under moderate to moderate/strong acceleration) but less often than HV.

    If you will be on the expressway, then yes, it’s better to be in HV mode and save the EV section for the city. Of course ideally, you want to reach your charger with in HV mode so that you can top up fully (and that you’ve used up the EV portion and ran the engine as little as possible).
     
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  9. GKL

    GKL Active Member

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    Thanks, it was definitely worth the 120+ day wait :D

    …..and thanks for the tips, good points, it's good to learn from those who have driven one for a while and learn from their experience !
     
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  10. mr88cet

    mr88cet Senior Member

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    I personally don’t use EV Auto, but my understanding is that it’s basically the same as EV mode, except that it will sometimes kick in the ICE to reduce battery drain when you floor it.

    Now the mode I wish it had could be sorta the opposite: Normal HV power management, except that puts an absolute lower limit on the moment-to-moment MPG, say 48ish. So, for example, if you “step on it” in normal HV mode, it guns up the engine RPM, and the MPG momentarily drops to zippo. In this hypothetical mode, it would instead burn down the battery for that added power, but still use gas for long, sustained power where the ICE can run at maximum efficiency.
     
    #10 mr88cet, Jun 14, 2020
    Last edited: Jun 14, 2020
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  11. GKL

    GKL Active Member

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    Thanks for sharing that, now I'm thinking about the other modes "normal, eco, and power", not interested in power mode so as to keep MPH up, but have been using "eco" mode, but did a forum search and saw comments where many people prefer normal mode over eco mode and said it didn't make a big difference in MPH.

    Another comment I read said eco mode might be best for short trips and normal for longer trips, also that weather can be a factor too like if you live in the south and have to use the A/C a lot during the summer months. Something else I'll need to research :D

    As far as between EV-Auto and Hybrid mode, I'm thinking keep it in EV mode until we get on the expressway (when we do longer trips) and switch to Hybrid mode for expressway speeds.
     
  12. Tideland Prius

    Tideland Prius Moderator of the North
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    I believe the DRCC is tied to Eco or normal mode in terms of acceleration after the car in front of you changes lane or speeds up. But yeah, since you’re typically cruising on the highway, normal mode works. It feels more responsive when you want to pass or accelerate.

    Note that in normal mode, the climate control also goes to normal mode. If you want to keep it in Eco Heat/Cool, you’ll have to press that button to enable that function. (It’s automatically enabled when you select Eco mode)
     
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  13. GKL

    GKL Active Member

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    We usually do about 95% of our driving in our small local town where all our running for one day should normally stay less than 25 miles so we use EV mode for local driving (most roads in town are 25-35MPH expect the bypass which is 45MPH)

    Very occasionally we'll go to the closest big city (about 25 miles away) and the road going to the expressway from town is 55MPH once you leave the town limits, then the expressway is 70MPH for the most part.

    When we have it in Eco mode does that make any real difference over Normal mode when you're driving in EV only mode ?

    When only driving locally in EV only mode does it make any signifigant differences at all whether you have it in Eco or Normal mode ?

    Note: being in the south we often have to use the A/C when driving during the summer.

    Thanks !
     
  14. mr88cet

    mr88cet Senior Member

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    My immediate suggestions would be:

    First, if you have better things to think about, so to speak, just hop in and drive. The computer does a good job optimizing the drive system.

    Second, if you know you can do your current trip on a single charge, then just keep it in EV mode.

    Third, if you have a long trip, keep it in HV for long spans at highway speeds, and switch back to EV for driving through towns with stop and go traffic.

    Fourth, again related to long road trips (necessarily) in HV, remember that it gets quite impressive mileage up to 55-60ish. I often see 60MPG, if I conditions allow me to keep my speed fairly consistent. However, mileage plummets rapidly above 60MPH, due to wind-resistance. At 75MPH, I rarely see much better than 48ish MPG.

    With respect to Eco vs. Normal vs. Power modes, a few things:

    First, in EV mode, this setting seems to be mostly just “throttle mapping,” meaning that EV Power mode mostly just interprets half throttle as a higher power setting than half-throttle in Eco. However, EV Eco mode also seems to automatically ease off the power a little after you get up to 30ish MPH.

    Second, switching to Eco mode also automatically turns on Eco climate control. You control that explicitly too.

    Third, Power vs. Normal vs. Eco doesn’t appear to be strictly throttle mapping in HV mode. In HV Power mode, it also seems to idle the engine more, ready for a jackrabbit start.
     
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  15. GKL

    GKL Active Member

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    Thanks for the ideas !

    EV mode is what we use for local driving as we likely should stay under 25 miles per day when staying local.

    As far as being in EV only mode does it matter much if you use normal or Eco mode ?

    On our longer trips (over the EV only range) the expressway speed is mostly 70mph, and since many drivers like to go more than the limit we would have to stay at least at 70-75mph to not have people feel like we were impeding traffic flow, so the 60mph and under benefit would not be available on the expressway :D
     
  16. mr88cet

    mr88cet Senior Member

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    I myself do the vast majority of my driving in EV Eco, but no, I personally haven’t really seen much difference in range between Eco vs. Normal vs. Power mode, for EV driving.

    Yeah, you definitely don’t want to drive much, if any, slower than the traffic around you. Heck, even 48MPG at 75MPH with the AC on is not bad!
     
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  17. GKL

    GKL Active Member

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    Thanks, I was also wondering if when driving local in EV only mode that not only if the range was effected (you said you didn't see much difference in range) but also if having it in Eco mode made any big difference in how much drain on the battery is done by having the A/C on.
     
  18. mr88cet

    mr88cet Senior Member

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    The AC and heat pump are quite efficient, but they do cut in on range a bit. Not surprisingly, how much they do so depends upon how big a temperature difference you ask for. I generally, in hot weather, set it at 78ish, and find that it only loses a couple miles of range or thereabouts. All in all, I find that the heat pump is a little less efficient than the air conditioner, but not by much.
     
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  19. GKL

    GKL Active Member

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    Good idea, make it just cool enough to be comfortable, don't need to chill like it's winter, the idea is to keep from sweating not feel cold, we'll have to see what temp works for us.
     
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  20. mr88cet

    mr88cet Senior Member

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    Indeed! If you cool it down to 72F, you probably won’t lose more than a further couple miles or so, assuming it’s rather hot outside. If your ‘Prime has the Remote-Climate feature, that can be helpful as well.

    In colder weather, the steering wheel and seat heaters can go a long way too. I have found the steering wheel heater amazingly addictive , and that I don’t need to use the heat pump or seat heaters much.

    Then again, I live in Austin TX, where three months out of the year, highs around 100F are pretty common, and lows in Winter only occasionally go below freezing. So, that’s the particular grain of salt to take my comments with!
     
    #20 mr88cet, Jun 15, 2020
    Last edited: Jun 15, 2020
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