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Traction battery question

Discussion in 'Gen 4 Prius Main Forum' started by HamiltonPrius, Jul 5, 2016.

  1. HamiltonPrius

    HamiltonPrius Member

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    I have noticed most mornings when I start my Prius the traction battery has discharged down to 2 bars overnight. At this level the gas engine kicks in and runs until the battery charges up to 3 bars and thus lowering my gas mileage figures.

    My question ....is it common for the traction battery to discharge to this level overnight?
     
  2. GaryD1

    GaryD1 Active Member

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    this don't sound right, doesn't on gen 3.
     
  3. bisco

    bisco cookie crumbler

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    the engine always starts when the car is cold. you won't get good mileage on short trips.
     
  4. bisco

    bisco cookie crumbler

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    it is most important to note how many bars when you shut down for the night, so how many are you losing?
     
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  5. alanclarkeau

    alanclarkeau Senior Member

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    Mine doesn't always start when cold, though will when I get to the hill around the corner if I go that direction - it always does if I have A/C on, though.
     
  6. HamiltonPrius

    HamiltonPrius Member

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    The battery bars on shutdown varies.
     
  7. HamiltonPrius

    HamiltonPrius Member

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    Cold, hot doesn't seem to matter. The determining factor is battery charge. If battery is at 2 bars the gas engine kicks in. Three bars or higher gas engine stays off.
     
  8. bisco

    bisco cookie crumbler

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    yes, that is the standard. the question is whether you're losing significant charge overnight. 1 to 2 bars seems to be within parameters.
     
  9. HamiltonPrius

    HamiltonPrius Member

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    bisco, where did you get this information from?
     
  10. bisco

    bisco cookie crumbler

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    reading peoples experiences here.
     
  11. HamiltonPrius

    HamiltonPrius Member

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    Thanks bisco, could you please post a link or two relevant to this subject so I can read some other owner experiences.
     
  12. David Beale

    David Beale Senior Member

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    It's not the charge level in the battery that is changing, it is the charge indicator that is. It's a guess at best.

    The GIII would run the engine through a "cat warmup cycle" each time you started the car. It is my understanding that the G4 is not supposed to do that. But if the system thinks the battery is getting lower on charge it WILL run the engine to charge it back up to about 60%.

    So your observation may be related to the HSD incorrectly thinking the battery is down and trying to compensate. Perhaps ambient temp related?
     
  13. bisco

    bisco cookie crumbler

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    i'm sorry, but the posts about battery charge level are too random to find a link. it's just my observation over many years spent in priuschat delinquency.

    why don't you start logging your shut down number of bars showing data, and the number on start up the next day. post them here, and i think you will get better opinions of what is happening, if anything.
     
  14. eric1234

    eric1234 Active Member

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    I have never noticed any "self discharge" on either my GEN III or GEN IV

    If you are really losing charge measure overnight, you should have that checked - something might be wrong.