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ICE cycling?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by engunneer, Jun 4, 2005.

  1. engunneer

    engunneer Member

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    Went on a camping trip for Memorial Day on Whidbey Island in WA. Coming back to the ferry on Monday afternoon, we came down a very long slope. at about 50MPH with some, but small, braking. The bottom of the hill is the ferry terminal. I know the ICE goes to B mode when the battery if full, but that doesn't seem to be what happened. Once we came to a complete stop in the ferry terminal line, after a short pause at a light that shut off the ICE, the engine started cycling on and off to bleed of the battery. The frequency was about one second on, one second off. This was disconcerting because we had stopped, so I assumed we'd just have everything off and use the battery up when pulling onto the ferry. It took about 30-60 seconds of cycling before the ICE just stayed off. Is this normal? Has anyone else done this? I'm not especially worried, but I thought I would ask.
     
    #1 engunneer, Jun 4, 2005
  2. efusco

    efusco Moderator Emeritus
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    Ah, no it doesn't do that at all.


    Completely normal...as you surmised the battery was just spilling power in the most efficient way possible. It takes a goodly amount of energy to spin up MG1 and the ICE. Doing that a few times drains the battery back down to ~ 80% SOC...it's "happy place".
     
    #2 efusco, Jun 4, 2005
  3. DanMan32

    DanMan32 Senior Member

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    I agree, if you aren't moving, why bother running ICE? Even the DC/DC converter will use some charge from the HV battery, and the HV ECU could use the battery to go into pure EV when you finally get moving.

    Now if you were regenerating downhill, with nowhere for the energy to go but to constantly restart the ICE, that I can understand.
     
    #3 DanMan32, Jun 6, 2005
  4. efusco

    efusco Moderator Emeritus
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    <div class='quotetop'>QUOTE(DanMan32\";p=\"96009)</div>
    Interestingly, I have a very long grade I go down on the way to my lake property. I always see a full 8 bars before I reach the bottom where I, more often than not, have to stop at a light. Almost never, any more, does my ICE do this dump cycling like it used to. In fact, even with just 6-7 bars I used to have cycling of the ICE when I stopped (very early weeks/months). I suspect the firmware has been changed since the first releases. I also suspect that as the battery ages the threshold for the cycling routine changes.

    I can confirm neither so please don't go crazy challenging me or anyone else on this, but it's an observation. I can think of only one time in the last 6 months with a full or near-full battery where the ICE has done a 'dump cycle' like that.
     
    #4 efusco, Jun 6, 2005
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