ICE starts during full 'green' bars when car is stopped, does not with lesser charge.

Discussion in 'Gen 2 Prius Main Forum' started by George W, Nov 24, 2018.

  1. George W

    George W Active Member

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    With the cooler weather here in Southwest Texas, I find that my Hybrid battery goes green a lot more often. Usually when at a red light, the ICE doesn't come on until I take my foot off of the brake pedal getting ready to accelerate. Now when I have full Bars in the green, the motor starts up at least twice a minute while stopped. Any idea why? Thanks.
     
  2. PriusCamper

    PriusCamper Senior Member

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    First guess is the engine is running more in Summer because of your air conditioner... The other issue is, as your hybrid battery ages it loses capacity and can lose up to 50% total capacity and still function normally. You can restore capacity and extend lifespan of your pack by doing battery reconditioning. learn more here: FAQ
     
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  3. bisco

    bisco cookie crumbler

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    when charging exceeds pack capacity, the engine will burn off the excess. as the pack ages, capacity is reduced. totally normal
     
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  4. George W

    George W Active Member

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    Thank you both for your quick response. I recently had the wiring harness replaced. Since then, the Hybrid battery gets a better quality charge and shows green bars more often.

    Before the harness change Hybrid Assistant never showed more than about a 50 to 57% charge. After the harness change, I'm frequently showing 60-70% charge. On the few occasions when I have full bars, hybrid assistant shows about a 76% charge . Undoubtedly is influenced by the cooler weather, the slightly different way in which the internal combustion ramps starts and stops at the higher level is something I still haven't quite gotten used to. Thanks
     
  5. kens97uber171

    kens97uber171 Active Member

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    If it is cool enough to not need AC, then the battery will go green more often.. and sooner.
    If it's cool enough to need heat in the car the ICE will run to keep the car interior at the set temp. You can turn the climate control OFF see if that makes a difference.
    Also in cooler weather the car will run the ICE to keep the engine coolant and exaust temps at a certain level for emissions reasons.
    I notice the ICE starts for short times at odd and seemingly unexplainable reasons more in the winter than summer.


    Posted via the PriusChat mobile app.
     
  6. bisco

    bisco cookie crumbler

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    what happened to the wiring harness?
     
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  7. PriusCamper

    PriusCamper Senior Member

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    I bet it was corrosion in the voltage sensor wires giving bad readings...
     
  8. George W

    George W Active Member

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    It was showing signs of corrosion after the HV battery was removed for testing.
     
  9. wjtracy

    wjtracy Senior Member

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    It also depends on what Hybrid warm up stage you are in.
     
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  10. PriusCamper

    PriusCamper Senior Member

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    Take it back to mechanic that worked on it and say they didn't finish the job... There's endless amounts of information on here about how to do the job right and replacing a wiring harness without even first cleaning the existing harness and reconditioning the battery pack and load testing the modules to make sure there's no bad modules is irresponsible and lazy at your very significant expense. Sounds like the mechanic didn't even do the testing that you paid for... Sorry you had to go thru this. The mechanic screwed this job up!
     
  11. jerrymildred

    jerrymildred Senior Member

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    Because the weather is cooler, the engine takes longer to warm up and it cools down more quickly. The computers want to keep it at normal operating temperatures to maintain the lowest possible emissions so it runs more in the winter than in the summer, especially if you are running the heater, which cools the engine even faster. So, running the A/C less and the engine more, will result in a higher state of charge most of the time in the winter than in the summer and also lower fuel economy.
     
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  12. wjtracy

    wjtracy Senior Member

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    ...also to get into the final stage, the car has to be fully warmed up AND the vehicle to come to a full stop. From that point forward you will be in Stage 5, but in some cases, you are driving around in Stage 4 because the "full stop" has not yet been executed.
     
  13. George W

    George W Active Member

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    I would like to believe in that. However, changing the harness has not improved the high temperature-sensor readings. I'm having to run the fan ( using Hybrid Assistant) constantly to keep temps close to 100.
     
  14. PriusCamper

    PriusCamper Senior Member

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    Well in that case, it's likely one or more of the 168 battery cells in your pack is starting to fail... The harder option is to do individual module reconditioning to identify the weakest one and replace it. The easier option is keep the fan on full blast and wait till those cells get bad enough to trigger the warning lights and then identifying the bad cell(s) will be much easier. The most expensive option is to buy a battery pack and sell/trade your old one to someone who will be pleased to have a pack to work on that hasn't failed yet and will give you a failed pack to turn in for you core deposit.
     
  15. George W

    George W Active Member

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    Isnt it possible that the temp sensors could be failing? What do they connect to? What component decides whether these thermisitors are accurate?
     
  16. PriusCamper

    PriusCamper Senior Member

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    Yes that would be true if the vehicle was automatically running the hybrid battery cooling fan at full blast, but OP states that they're manually running the cooling fan at full speed via the hyrbid assistant app.

    But in general, yes, it's pretty easy to bump or incorrectly mount temparatrue sensors in a way that would give bad readings.

    Hopefully the hybrid cooling fan is clean and that's not an issue.
     
  17. Skibob

    Skibob Senior Member

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    If you bumped the sensors wouldn’t be more likely to read lower rather than higher? Plus the OP does not mention if the fan will go up on its own, or he just forces it to that speed.
     
  18. George W

    George W Active Member

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    I have to use an App to hear the fan at all. This could explain why the battery temperature always wants to hover around 120 degrees. With hybrid assistant I can at least keep the temp around 100.

    What I don't know is, what controls the fan ? Is it some circuit board around the high-voltage battery? Is it a circuit located under the hood? How can I test the Integrity of temperature-sensor?

    Without a third party app to force the fan on, I never hear it ever turn-on. I should think that is one of the parameters the car should be engineered to self test.
     
  19. jerrymildred

    jerrymildred Senior Member

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    As I understand it, there are three thermistors in the battery that connect to the battery ECU. The resistance of the thermistors varies with temperature. The ECU uses that information to calculate the battery temperature and adjusts the fan speed as needed. I don't know the details of whether the ECU measures resistance directly or if it's measuring a voltage differential based on a voltage source external to the ECU.
     
  20. PriusCamper

    PriusCamper Senior Member

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    Yes, it's way more likely bad sensor placement will lead to cooler reading rather than hotter, but hotter is still possible for some of them.
     
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