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. PriusCamper

    PriusCamper Senior Member

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    Yes... The battery pack has to get really hot or fan really clogged up to run loud... Are all the temp sensors within range of each other, or is one sensor significantly different than the others?
     
  2. George W

    George W Active Member

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    2 of the sensors usually indicate within a degree of each other. The third indicated 4 degrees cooler
     
  3. PriusCamper

    PriusCamper Senior Member

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    In that case... Overall, everything seems pretty normal... The only issue is that as a battery pack ages it loses capacity... When you have full green bars, the engine is spun to use excess electrical energy to prevent risk of overcharging. The more capacity your battery loses, the more quickly it will hit full charge and spin the engine to use excess electrical energy.

    The fix is either a new battery pack or battery reconditioning to improve and extend lifespan of your existing pack.

    Learn more here: FAQ
     
  4. The Electric Me

    The Electric Me Go Speed Go!

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    I don't think the engine starting more often here, has anything really to do with the battery charge level.
    If the battery is reading full charge or near full charge the engine isn't starting to charge the battery or "burn off exess charge".

    What people forget is the Prius is designed to maintain clean emissions. So the Prius runs it engine to keep it at certain a minimum operating temperature so that the exhaust system can operate with those low emission standards. When it get's colder, and the vehicle is stopped, the engine is going to cool down faster, and trigger it's own start more often.

    The OP say's the engine is "starting" more often when he is at a STOP. Which means, the Engine isn't starting or turning...to burn off excess electric charge, because the vehicle isn't moving....NOTHING is turning. The battery does not power the ICE, when it turns on...it's running on gasoline.

    Basically, the Prius engine starts up to maintain engine temperature, charge the battery when it is low (not the case here, since OP says full green bars ) and to work as a vehicle engine with HSD to power the vehicle.

    Turning on twice a minute while stopped? Doesn't seem normal to me.
    If you are stopped for a full minute, and it turns ON and OFF at least twice, I'd say there is some communication problem.
    I'm wondering if an engine thermostat isn't dying.

    On colder days, my engine would run more often, but it would also be more "consistent". That is...run until the engine was warmed up...then stop. Or run until the battery reached a minimum charge level, then stop. Neither action was as brief as to be a turn on/off action twice a minute. Once the engine reached the minimum operating tempature, even on cold days it would hold it...for quite a while. And once the battery was charged "enough"....the ICE also would stop turning on, as it wasn't necessary.

    You've got an older battery, and the OP changed the wiring harness.
    The OP admits that since the wiring harness change, what the usual Hybrid Battery charge level reading seems to of changed.

    I think, this could be a sign of early failure of the Hybrid Battery, or the system misreading some information. My guess, engine temperature, or what IT thinks the battery charge level actually is....

    Let me caveat everything by saying I could be totally wrong. BUT....it doesn't sound "normal" to me.
     
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  5. PriusCamper

    PriusCamper Senior Member

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    Yes, agreed that engine fires up to keep the temperature optimized, but NiMH batteries don't last very long if they're overcharged too often so there are times when the ICE is used without fuel to back off of a peak charge a bit... Just as Bisco said in #3 of this thread:
     
  6. The Electric Me

    The Electric Me Go Speed Go!

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    But the OP is saying the engine is turning on...at a stop.
    I get that the engine is actually...firing...that is burning fuel. Not just "turning" or coasting without fuel consumption.
    In fact to my knowledge, at a complete stop? There is no way to make the engine "turn", powered solely by the battery.

    But hey, I could be wrong.
     
  7. PriusCamper

    PriusCamper Senior Member

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    Bisco explained it in Post #3, I repeated in previous post... I'll say it yet again... NiMH battery pack longevity depends on making sure they don't get over-charged. Toyota address this issue by intentionally discharging the battery pack when it reaches max charge.

    One of the most efficient ways do that discharge is for the hybrid battery pack to use the electric motor to spin the engine. In the same way we use engine spinning / downshifting to slow a descent down a hill, so too the prius slightly backs off / discharges it's battery pack from full charge by using that same resistance from the engine.
     
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  8. George W

    George W Active Member

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    Without the App, I never hear the fan. The temp simply climbs to 120+. The Hybrid Assistant App controls the fan speed in 'Auto' mode, depending on the temperature info it gets from the car.
     
  9. PriusCamper

    PriusCamper Senior Member

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    Yes, but the hybrid battery computer will speed up the fan to full speed on its own when temps get too high. I've never heard of it failing to do this. Are all the temp readings from the pack the same? Maybe you're looking at just one of the readings and not all of them and that one hot reading is not correct?
     
  10. George W

    George W Active Member

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    The Hybrid Assistant reports 3 different temps, two typically agree and is higher than the third. The app starts the fan at 96 and keeps adjusting the speed until it gets the temp below that mark.
     
    #30 George W, Dec 11, 2018
    Last edited: Dec 11, 2018
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