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Have you noticed that your HV SOC decreases as you coast? I have...

Discussion in 'Gen 2 Prius Technical Discussion' started by Jimbo69ny, Mar 28, 2012.

  1. Jimbo69ny

    Jimbo69ny Active Member

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    I am using Torque and, among many other PID's, I am monitoring HV SOC, MG1 and MG2 power.
    Why is it that even though there are no arrows on the MFD AND both MG1 and MG2 show 0 that I am still losing battery charge? Its not a lot. Not nearly as much as if I were running on electric only. I havent watched the odometer while this is happening but I would guess that I lose about 1.5 % of charge every quarter mile or so.

    Everything else seems to work fine. The hybrid battery holds a charge otherwise. i.e. overnight. Its just annoying because my trip home from work is about 6 miles. Most of the trip is around 35 mph, in a gradual downhill road through Cornell's south campus. I can coast almost the whole way but at the end my battery ends up being many percentage points lower even though I am using minimal power. Today my trip home was 95mpg.

    Im doubt there is anything I can do about this. I just thought it was strange.
     
    #1 Jimbo69ny, Mar 28, 2012
  2. Rokeby

    Rokeby Member

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    All is not as it appears!

    First off, the Energy Monitor screen is a simplification of what's really going on.
    As an example, there are really two Motor/Generators (M/G), but only one is
    shown. For at least this reason the display is considered to be a "mimic".

    You hear a lot about the "no arrows glide" being a condition where there
    is no electrical flow either into or out of the HV battery. This is not accurate.

    It has been verified that during a "no arrows glide" there is a small amount of
    electricity going from the HV battery to an MG. IIRC, it represents ~.7HP. Some
    folks have said that even this little amount of power contributes to the extra-
    long allegedly unpowered glide distances achieved by the Prius.

    If you want to conserve this small drain from the HV, it can be averted.
    These thread discusses the pros and cons of gliding in neutral:
    http://priuschat.com/forums/gen-ii-...al-when-driving-increase-mpg.html#post1128908
    http://priuschat.com/forums/gen-ii-...parison-methods-pedal-control-vs-neutral.html
     
    #2 Rokeby, Mar 28, 2012
  3. jpadc

    jpadc Type before I think too often

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    Don't forget the HV battery is powering the inverter, the AC, blower fan, lights radio, charging the 12 volt battery and every other electronic and electrical component of the car. All power comes right out of the HV battery and at a non-trivial rate.
     
    #3 jpadc, Mar 29, 2012
  4. Jimbo69ny

    Jimbo69ny Active Member

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    Thank you. Thats a good answer. Makes sense.
     
    #4 Jimbo69ny, Mar 29, 2012
  5. Jimbo69ny

    Jimbo69ny Active Member

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    #5 Jimbo69ny, Mar 29, 2012
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