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Odd ICE behavior on start

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by PhilBlank, Jul 15, 2014.

  1. PhilBlank

    PhilBlank Junior Member

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    I have a 2014 PIP Advanced/Tech package. I park on a hill. I have noticed, in the morning when I start out, the ICE almost always comes on. I am presuming (or I did until today) that is was sensing an 'overcharge' condition on the traction battery and was compensating (I charge everynight and start off full). This morning, I pulled out of the driveway in EV...got then went into neutral for about a 10th of a mile, then back into drive. I had started in the driveway with 12.4 of estimated range...by the time I was at the bottom of the hill, I had 12.6. The ICE did not come on at all. In fact, it did not come on until I went into Hybrid mode as I approached the freeway on-ramp. Prior to this morning, the ICE would always start going down that darned hill and I could never figure out why.

    So anyway, for all you charging experts out there. Any idea why going into neutral for a short period of time would, in this particular use case, cause the ICE not to start?

    Thanks,

    Phil
     
    #1 PhilBlank, Jul 15, 2014
  2. JBumps

    JBumps Member

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    I'm no expert, but also live on a hill and have seen similar behavior. It seems as though the engine will remain in shutdown, even if 'over charged' so long as regen is not being applied and SOC isn't too high. The run-through is likely a preventative measure, designed to give the car an outlet for the generated energy, rather than sending to the pack or riding the mechanical brakes.
     
    #2 JBumps, Jul 15, 2014
  3. bisco

    bisco cookie crumbler

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    what is the length and total elevation drop?
     
    #3 bisco, Jul 15, 2014
  4. chesleyn

    chesleyn Active Member

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    This was discussed in length a few years ago when the PiP was first released. Yes the ICE is working to absorb some of that excess energy which prevents the battery from overcharging.

    If you turn the AC on and put the fans on high, the battery will take up to 86.4% SOC.

    Another option is the utilize only the break pads by coasting down the hill in neutral.


    iPad ? HD
     
    #4 chesleyn, Jul 16, 2014
  5. gallde

    gallde Active Member

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    As I understand it: When fully charged, even if you apply the brakes going downhill, the MG spins and will have to spill energy in order to not overcharge. Therefore, MG2 transfers the excess to MG1, which spins the ICE. When in Neutral, no MG is spinning, so no power is being generated, therefore, the ICE need not spin.
     
    #5 gallde, Jul 16, 2014
  6. PhilBlank

    PhilBlank Junior Member

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    OK...thanks for the information...a couple of items...it is about 300 foot drop down the first hill....I was making the assumption that the ICE was on and actually burning fuel (rather than just spinning) as the MPG gauge drops to approximately 50 MPG. Once the engine cycles off, I stay on electric thoughout the entire day.

    But none of this explains why a short time in neutral seems to prevent this from happening.

    OK as a newbie...need some help...MG=? MG1=? MG2=? and what is SOC?

    Thanks everone
     
    #6 PhilBlank, Jul 16, 2014
  7. -Rozi-

    -Rozi- Member

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    They did explain... Too scientifically obviously. Let me try it:
    Yes, in your case PiP was fighting against both: overcharging the battery and using friction brakes. When in N you force PiP to use regular friction brakes and skip the regen and engine braking. Don't over use it!
     
    #7 -Rozi-, Jul 16, 2014
  8. chesleyn

    chesleyn Active Member

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    I really never figured out the MG1 and MG2, but those are the "gears" of the electric motor. One of them is what captures and regenerates energy into the battery. The computer on the car will not allow the battery to charge beyond 85% SOC (state-of-charge). I used SOC because that is the gauge I look at on the scan gauge 2.

    I have the exact same problem at work. The parking lot is at 1200 elev and there is an immediate drop of 300 feet down to the first red light. I've used the AC on high, I've used the neutral and only friction pads, and I've let the ICE kick on and absorb. In all reality for the 30 mile commute home, I haven't really noticed a major difference in MPG. The nice thing about the drop in elevation is that I live in a beach city, so my home is at 7 feet above sea level. The entire commute is pretty much down hill. I get about 22 miles of EV on my return drive.
     
    #8 chesleyn, Jul 16, 2014
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