Most decent way to run your 115V essentials out of Prius Prime

Discussion in 'Prime Technical Discussion' started by Krzysiek_KTA, Jun 7, 2020.

  1. m8547

    m8547 Senior Member

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    The post I was thinking of said, at 20mph or whatever they tried, shifting to reverse actively decelerates the car then starts reversing. I've tried it rolling forward up to few mph and it does that. Is there a speed above which it actually goes into neutral not reverse? If it actually goes into reverse at a considerable forward speed, and if it thinks the accelerator is stuck down, that could make it quite difficult to control the car.
     
  2. ChapmanF

    ChapmanF Senior Member

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    Gen 1 does. It has a conventional ignition key on the steering column, and locks the column when the key's removed. Since the introduction of the pushbutton in Gen 2, the anti-theft box is checked by the PITA-to-access parking lock motor instead.

    The latter, of course, is what happens. Everything's already moving forward; shifting the direction of torque doesn't create any mathematical singularities, the car just loses forward speed, crosses zero, and picks up speed in reverse.

    You can do it, if your forward speed is less than 6 MPH or so, and see how it feels. There's nothing especially dramatic about it. It would feel about the same (only taking longer to reach zero and start reversing) from higher speeds if the computer would let you, but the voltages/currents involved would be higher, so the computer just double-beeps and gives you neutral.
     
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  3. fuzzy1

    fuzzy1 Senior Member

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    Other members in past threads have found and posted the threshold speeds for Reverse and Park, above which the ECUs override and choose Neutral instead. I don't remember the actual numbers.

    The consensus was that for Park, the max speed it allows does create quite a jolt, but is well within the strength of the parking pawl. As Chapman mentions, Reverse creates no mechanical jolt, just some reverse torque or force, nothing excessive. I occasionally shift from R to D while still moving slowly in the parking lot, it is nothing different than doing the same in a manual transmission while gently letting out the clutch. No big deal.
     
  4. OptimalPrime

    OptimalPrime Member

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    I'd forgotten that MG2 is what gets reversed, and is also what is basically connected to the wheels rather than to the sun gear like MG1 or to the planetary carrier like the ICE. I was debating whether it was hooked to the planetary carrier versus the wheels. I wasn't sure which was hooked to what, that's all, and I knew it's trickier than it sounds.

    So actually it's the ICE rather than MG2, which you could reverse the direction of without needing the car to reverse direction. But we all know the ICE only goes in one direction, or stops. Had MG2 and the ICE been swapped in terms of what they're hooked to, your "of course" comment would be wrong, the answer would be reversed.

    I was not suggesting that any acceleration, either angular or linear would become infinite, or anything mechanical would instantly reverse direction. But they can reverse direction a lot more quickly than the car does, if not directly tied to the car's motion. I just forgot that the one the shift lever reverses, is the one actually tied directly to the car's motion rather than to tricky gears. I'm not Newton or Dirac, but I do understand what they said. Or at least I did at some point, hahaha.
     
  5. ChapmanF

    ChapmanF Senior Member

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    Can you give any clearer picture of what such a "reversed" answer would look like?
     
  6. jerrymildred

    jerrymildred Senior Member

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    All you ever wanted to know, and probably more right here. The tldnr version is that the planetary gearset remains the same, but the layout is different and the MGs are smaller but spin faster, plus the Prime has a one way clutch allowing both MGs to power the car up to 84 mph.


    Here's a quick look video.
     
  7. Boomer 2298

    Boomer 2298 New Member

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    loved those every other day rules and rationing.
     
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  8. Randy B

    Randy B Junior Member

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    I have sometimes encountered a regular Prius running the 12v battery down when ON and in Park for extended periods. My guess is that the Prius converter may not charge the 12v battery when the dash display shows 1-2 bars on the traction battery, as will occur when running ON and in Park. A workaround is to drive the Prius around the block for 5-10 minutes to bring the traction battery up to 3-5 bars and consequently the 12v battery gets charged too.
     
  9. ChapmanF

    ChapmanF Senior Member

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    If it was really ON (and not READY), there's an even simpler explanation. The converter isn't even operating then.
     
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  10. jerrymildred

    jerrymildred Senior Member

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    If it's just ON and not READY, it won't charge the 12V even if the dash display shows 8 bars. The workaround is to do like the owners manual says and have it in READY so the converter that Chap mentioned will do its job and charge the 12V. No need to drive it; just READY it. The car maintains the 12V all the time it's in READY and none of the time it is not in READY -- regardless of the SoC on the traction battery.
     
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  11. Randy B

    Randy B Junior Member

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    Chapman, Good thought, but the Prius is READY and in Park. Running 2-3 days and found the 12v low. Car started 1st time, but shut off and 2nd start failed. Needed big recharge of the 12v. Driving around block charges nicely. Trickle charger might help, too.
     
  12. ChapmanF

    ChapmanF Senior Member

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    It would be interesting to leave that car running with a data logger or chart recorder on the 12 volt voltage.

    The converter doesn't have any direct control over whether it does or doesn't charge the 12 volt battery ... that's only determined by the voltage it is putting out. If that drops below 13 or so, it won't be charging. It would be good to look at a data log of the voltage and try to spot the point where the voltage dropped, and what it dropped to.

    If there were a log of various other things, like traction battery SoC, converter temperature, etc., it might be easier to spot what the drop-out coincided with.
     
  13. m8547

    m8547 Senior Member

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    I think the owners manual has an obscure line about something happening to the 12V system after 20 hours of continuous driving (and I assume parked in ready mode is equivalent to driving).
     
  14. ChapmanF

    ChapmanF Senior Member

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    Are you talking about a Prime? Randy was saying it had happened in a regular Prius. I don't remember ever seeing such a line in an owner's manual, but they're online so shouldn't be hard to check. Do you remember what model year manual you are thinking of?
     
  15. Elektroingenieur

    Elektroingenieur Senior Member

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    It’s in New Car Features, quoted previously.
     
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  16. ChapmanF

    ChapmanF Senior Member

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    I have a bad habit of forgetting that somebody who says "regular Prius" could be talking about a Gen 4.

    I still wonder, as I did in that earlier thread, whether there was an element of (some added 12v load on the wrong side of the battery state sensor) playing a part in the story.
     
  17. Krzysiek_KTA

    Krzysiek_KTA Active Member

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    Let's revive the main purpose of the post. Shall we?

    In current ongoing power outages in Houston I manged to survive just using PRIME as power supply with 45min-1h recharging interruptions to my house essentials.
    My best guess is if the inverter load is around 700-850W the PRIME can last for 4-5 hrs wen recharged using CHG mode.
    Well worth the effort since I can still enjoy semi-normal life in black out times.

    Stay warm!

    Brgds

    Kris
     
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  18. Salamander_King

    Salamander_King Senior Member

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    I hope you are staying warm... maybe in the car, but don't do it parked inside of a garage. Stay safe. Take care.
     
  19. Randy B

    Randy B Junior Member

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    Good to know. Hope you stay safe and warm enough.. And, of course there are water concerns.
    If you leave the Prius in READY Mode, your 12v use can remain continuous. Please keep house loads to < 800w on a 1kw inverter.
    If you need more power, 3 and 5kw, contact plugoutpower.com.
     
  20. Krzysiek_KTA

    Krzysiek_KTA Active Member

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    Good note.

    I can tell 2017 Prius Prime can run anything below 900 W for 'prolonged' time like....4 hrs when charged to 80%...
    It works for me, but recharge times to 80% were over 1 hr in these inclement weather...
    other than that all works to stay connected, warm and sound!


    Cheers!