Charge mode

Discussion in 'Prime Main Forum (2017-Current)' started by park187, Dec 22, 2016.

  1. park187

    park187 Junior Member

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    I have a question about when to use charge mode and when to just use the default charging mechanism.

    If I were on a long trip driving on the highway at normal speeds, should I expect the traction battery to be full or empty, or perhaps somewhere in between? I would think it would be good to have a reasonably full battery most of the time, to help with hill climbing, or other acceleration demands. My understanding is that I can use charge mode to give the battery a boost with the ICE. Would it be advantageous to force this charging when descending a long hill, or would the car, in normal operation, do this charging without my intervention? How long would it take charge mode to replenish a depleted battery?
     
  2. Lee Jay

    Lee Jay Senior Member

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    Empty of Ev mode range.

    That's my suspicion too for long climbs, but it remains to be seen. Certainly for short climbs and acceleration, it doesn't matter as the battery isn't empty when it lacks Ev mode and can still certainly assist the same as a regular generation 4 hybrid.

    It can charge the Ev mode range up to 80% over a pretty long period of time (not sure how long, but on the order of a half hour or hour).

    My primary two planned usages are in advance of a major climb (thousands of feet) or in advance of entering a city where I know for sure I can't charge and where I will be doing short trips. This will avoid engine warm up cycles.
     
  3. john1701a

    john1701a Prius Guru

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    That's an interesting new misconception.

    It's easy to see where that assumption came from too. Volt has a "Mountain Mode" which is designed to fulfill that very need. It provides a 10-mile buffer on the battery-pack for times of high-demand. That most definitely is not what "Charge Mode" is for. Prius Prime already has plenty of power readily available. That's what "EV Auto" will provide automatically.

    "Charge Mode" is for special circumstances when you don't have the opportunity to plug in, but would have the advantage of EV mode efficiency if that electricity was available. In other words, if you are on long highway trip and your driving around at your destination will be just short jaunts where preventing engine warm-up would be beneficial, go for it.

    I routinely take trips like that. Once there, the running around from place to place is only a few miles. Being able to do that entirely in EV from electricity generated while efficiently cruising along the highway prior to that will be great. Being able to avoid having to run the engine at all will be a nice improvement, clearly enough of a gain to offset the earlier charging.
     
  4. Lee Jay

    Lee Jay Senior Member

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    How do you know that? Have you driven a fully-loaded Prime up an 11,000 foot pass at 65mph on a 7% grade? Has anyone?
     
  5. bisco

    bisco cookie crumbler

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    i suspect it will be helpful to have some battery charge for climbing long mountains, but only the most difficult, which have been documented here. without the extra battery power, a lift back can have difficulty maintaining speed. but this is a rare occurrence, and personal testing will need to be done. there are very few parts of the country where this is an issue.

    where do you live o/p?

    it is not necessarily 'good or bad' to have a full battery most of the time. generally speaking, you will use ev around town, and the gas engine on the highway. if you have a short enough trip, you can use ev for the whole thing, no matter the type of driving.

    deciding when to use charge mode, to save the warm up penalty, will be difficult if the purpose is to save gas. more gas is used in both cases.
     
  6. Neohippy

    Neohippy Active Member

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    Since it seats 4 has has small cargo capacity then fully loaded won't be much.
     
  7. Pizza Driver

    Pizza Driver Active Member

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    Having just crossed the Appalachians a little over a week ago, I can tell you that the Prime will not need a full battery pack to efficiently handle 6% upgrades in HV mode. In HV mode it barely eats into stored EV range at highway speeds in mountainous terrain, and can easily regen anything it used on the downgrades. For example, I started off from the dealership in Haegerstown MD with 4 miles of EV range. By the time I had made it just west of Wheeling WV (via Cumberland MD and Morgantown WV) I had increaded the EV range to 9 miles. The care had no problems tackling 6% grades at 70 mph.
     
  8. Lee Jay

    Lee Jay Senior Member

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    False.

    It has those things because it also carries 265 pounds of battery pack. Fully loaded, it will weigh the same as a liftback fully loaded.
     
  9. Lee Jay

    Lee Jay Senior Member

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    The Appalachians are at low altitudes. The ICE loses 30% of its available power in the Colorado Rockies but only 17% at the top of the Appalachians.
     
  10. Lee Jay

    Lee Jay Senior Member

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    Oh, heck. I just looked it up. On that trip, you barely exceeded 2,500 feet of altitude. The ICE will have 33% more power there than at the top of the Eisenhower tunnel approach.
     
  11. ForestBeekeeper

    ForestBeekeeper Active Member

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    I have not driven an 11,000 foot pass, yet.

    I do drive on the inter-state everyday with cruise control set at 82mph. 7% grades are not uncommon.

    I see no reason to think that doing 11,000 altitude should be any different.
     
  12. Lee Jay

    Lee Jay Senior Member

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    A 33% reduction in ICE power output due to altitude (less barometric pressure) is a reason.

    My 2004 will go up a 7% grade at 6,000 feet no problem without dropping below 3 bars. At 9,000-10,000 feet, it'll go from 8 bars to 1 bar in 4 minutes.
     
  13. JamesBurke

    JamesBurke Senior Member

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    Terrain view of PizzaDriver's trip from Younger Toyota in Hagarstown, MD to the I-70/I-470 merge near St. Clairsville, OH. There ain't no flat!
    upload_2016-12-24_22-53-35.png
     
  14. inferno

    inferno Senior Member

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    Does Charge Mode work by taking a % hit off your MPG because the system is focused on recharging your battery also? I've noticed that (and rightly so) Charge Mode causes me to lose torque and power from the HV system and forces me to use the engine more so (and I have to press the pedal harder).

    If it's a % hit off MPG then it would almost make sense to use Charge Mode going up a steep grade (whereas you would go from 25 mpg to 22 MPG versus 60 to 50) and perhaps downhill where regen + charge mode would recharge your battery faster and you would be getting 75+MPG...

    Correct me if I'm wrong :eek:
     
  15. jcburns

    jcburns Junior Member

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    Why, yes, yes we have. Just in the last couple of days. Drove our 2007 Prius out west, bought a new Prime in Oregon and we've just returned to Atlanta, via Northern California. Great trip. Lots of power up the coastal range and rockies, even with a car filled with a month's worth of luggage, presents, coolers, and so on. Ran full EV easily in Seattle, Portland. Ask us anything.
     
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  16. Lee Jay

    Lee Jay Senior Member

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    Where did you climb an 11,000 foot mountain pass at 60+mph?
     
  17. jcburns

    jcburns Junior Member

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    I knew I should have put on a nuanced disclaimer. The I-40 passes were 7300 ft-ish. The pass out of Taos on US64 was 9,820 feet (and we were going more like 62 mph.)
     
  18. Lee Jay

    Lee Jay Senior Member

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    Well, ~10,000 counts. 7,000 doesn't as my 2004 will do it at that altitude.

    My 2004 will climb these passes at 60mph, but it will quickly drain the battery to nothing in doing so. While it will still maintain speed on ICE power alone, even fully loaded, the empty battery leaves almost no ability to accelerate (think 60 to 65 in 30+ seconds, if it'll go at all).

    Did you see the Hv portion of the battery drain climbing the high passes?
     
  19. jcburns

    jcburns Junior Member

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    I think it more aggressively protects the HV portion, so no (we haven't apparently drained the HV portion ever), and we regenerated a LOT on the downslopes so that we had a mile or two of full-EV driving after a long downslope and then we were back to full HV. I should say that 'Power mode' (in HV as well as EV) is pretty amazing for blowing around giant dual-stack diesel-belching pickups on the freeways. Very much 'ludicrous mode' for the masses.
     
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  20. Lee Jay

    Lee Jay Senior Member

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    Power mode doesn't change full power performance. It just remaps the throttle response, unlike Ludicrous mode.

    Good to hear that it protects the Hv portion of the battery.
     
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