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Power loss when hybrid battery gets to two bars

Discussion in 'Gen 4 Prius Technical Discussion' started by Modero, Feb 26, 2022.

  1. Modero

    Modero Junior Member

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    I have a 2017 Prius. From the start it has always experienced power loss on the freeway when the hybrid battery gets to two bars. I don’t understand much about hybrid vehicles but this makes no sense to me. Has anyone experienced this?
     
  2. jerrymildred

    jerrymildred Senior Member

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    Welcome. We also have a 2017 trim 2.

    What are you doing that's making it drop to two bars on the highway? At two bars, the car will devote extra power to charging the battery at the expense of powering the wheels. But at highway speed, that should be pretty unusual.

    How many miles on the car? It sounds like you might have an engine performance problem that's making it use more battery power than it should.
     
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  3. slowmachine

    slowmachine Member

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    Back when the Gen2 was still new on dealer lots, I heard of a few being towed in because the driver had depleted the traction battery to zero by ascending a steep grade at full throttle. This is via my son, who has worked for the same Toyota dealer for the past 20 years. This is easy to do climbing I-8 eastbound from San Diego. Fast-forward to Gen4, is it still possible to deplete the battery by using its stored power to augment the ICE under heavy loads? If so, the car could be saving the battery by forcing the ICE to do all of the work.
     
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  4. bisco

    bisco cookie crumbler

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    my gen 2 and 3 has always kept the battery full on the highway. but it's mostly flatish around here
     
  5. jerrymildred

    jerrymildred Senior Member

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    There are stories of Gen 2 drivers continuing on after running out of gas and getting the traction battery too low to restart the engine after refueling. Newer generations, as I understand it, don't allow that to happen.

    But in preventing the battery from getting too low, if the hill demands more than what the engine can supply for too long, the battery will reach a point where the BMS says, no more battery for you. It will protect the remaining charge so that you will be able to start the car if you shut it off. At that point, you're limited to what the ICE can produce. It's time to slow down.

    I can see that happening. But I've never heard from any of our Colorado members of it happening to them and it never happened to me when driving up Grand Mesa or up to the tunnels on I-70. Then again, at 11,000 feet and 5-7% grade, I'm happy with 50 mph or less. And, as I recall, those are way more challenging than I-8 from San Diego to AZ. I've driven that both ways, but not in a Prius.
     
  6. Modero

    Modero Junior Member

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    Well the car has 104,000 miles now but it it has always had this problem. Performance problem…is this something a dealer can diagnose by checking the codes or something like that?
     
  7. bisco

    bisco cookie crumbler

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    if you have warning lights on the dash, then yes, they can read trouble codes and repair.

    if not, then no, there won't be any codes.

    unfortunately, no one here with a gen 4 (not prime) has commented on your experience vs theirs.

    what you are seeing seems abnormal to me. i would discuss it with the dealer, and perhaps they would be willing to go for a ride with you to see exactly what is happening.

    i'm sorry you waited 5 years to confront the problem, it might have been covered by warranty, although it may still be. could just be a lemon.

    generally speaking, dealers will not attempt to repair anything without codes, except items out side the computer controlled systems.
    a call to toyota corporate may be necessary.
     
  8. jerrymildred

    jerrymildred Senior Member

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    As @bisco said, they won't get any codes unless you have some sort of indicator light on the dash. But it still seems very abnormal unless you're charging up long steep hills at 95 mph so I think I'd get it checked out. My wife's 2017 had no trouble a couple years ago with some long, steep climbs on I-75 in TN and KY. And we had the cargo and back seat areas full of luggage. But we did slow down a little (as did many other cars) because it's just dumb to push an engine that hard for that long.

    It could be the the battery needs to be balanced or that you need a tuneup. But if it was like that new, then that's very strange imho.
     
  9. bisco

    bisco cookie crumbler

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    do you drive a lot of mountainous terrain? that's the only scenario i can think of that can produce your symptoms.
    sitting in stop and go can bring it down to two bars, but of course, you don't need power then.
     
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  10. vvillovv

    vvillovv Senior Member

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    If drive the same way most of the time and you've had the lssue for 104K, there's a lot of history data that's repeatedly added to the computer ECU. It seems to me, not an easy task to change the way the car performs if it's driven the same way that produces performance issues at 2 bars of SOC. (Is - Are) there specific time-(s) during the drive when you see 2 bars? Or do the 2 bar SOC performance issue-(s) show up randomly during your daily drive?