Kicking on Gas for Short Range Extensión With Heater On

Discussion in 'Prime Fuel Economy & EV Range' started by mr88cet, Jan 30, 2019.

  1. mr88cet

    mr88cet Senior Member

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    I think I’ve noticed something, and was wondering if you folks conclude the same:

    Suppose you’re cruising along with the heat pump off, hit EV/HV, wait a few seconds, then hit EV/HV again: I find it will kick in the engine long enough for it to warm up to a minimally-adequate temperature then switch back to EV mode within a couple minutes or so. So, this gives you a few miles of range extension with a fairly small burn of gas.

    Suppose you do exactly the same with the heat pump on: I find it will run the engine long enough to heat it up, not to a minimally-adequate temperature, but to a higher temperature where it can warm the cabin to the selected temperature (often considerably longer than a couple minutes or so), before switches back to EV mode. So this gives you a considerably longer range extension, burning considerably more gas, in the process.
     
  2. jerrymildred

    jerrymildred Senior Member

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    My PiP is similar, but without the heat pump, of course. If I'm in EV and I just pop it into HV and back to EV, it'll only stay in HV long enough to basically warm the engine (about 2-3 minutes). Interestingly, it warms so quickly that it doesn't extend the range much if at all. It's borrowing enough from the battery while the engine comes up to temperature that when it does warm up, it shuts down before it can put those miles back into the battery. So I don't get a whole lot out of that -- maybe a mile. If you're getting more than that, then that's a nice improvement.

    If I instead, turn on the heat while in EV, the engine comes on for a looonnng time.
     
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  3. mr88cet

    mr88cet Senior Member

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    Best I can tell, I seem to get 2-3 miles. Not much better than you’re seeing, but perhaps a little.

    I typically do this in the middle of my trip, when I’m driving at highway speeds, meaning that I get higher MPG for the ... quart or so? ... of gas burned. With the heat on though, I think I’m concluding that I’m better off just letting it kick in at the end of the trip so that I can cut the warm-up cycle short and burn less total gas, even if at lower MPG.
     
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  4. bisco

    bisco cookie crumbler

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    this is the story of my life. with 10-12 ev miles in winter, a lot of my trips wind up kicking the engine on just long enough for warm up. my concern is wear and tear on the engine and associated parts, as well as a major reduction in tank mpg.
     
  5. mr88cet

    mr88cet Senior Member

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    I gather that, since the PiP doesn’t have the sprag clutch the P.Prime has, and therefore can’t use both MGs, the engine ends up kicking briefly pretty often anyway?

    I get the impression that the PiP wasn’t fundamentally intended to drive long spans in EV mode, but more broadly just to reduce the % time the engine is used.
     
  6. bisco

    bisco cookie crumbler

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    i'm at 40,000 ev miles/20,000 hv miles. very little problem with engine coming on, but others mmv.

    not too much different from prime complaints of engine coming on when not expected, but a bit more i think.
     
  7. mr88cet

    mr88cet Senior Member

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    Interesting! So, does the engine frequently kick in when you accelerate?
     
  8. bisco

    bisco cookie crumbler

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    never, but i drive like an ol' lady. if you watch the hsi, the ice will kick if you push it to the power zone.
     
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  9. jerrymildred

    jerrymildred Senior Member

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    My experience is similar to @bisco's. I don't get to drive as high of a percentage in EV, though since I spend so little time on surface streets. I often have to use the engine to get out of the driveway at work unless I want to sit there and die of old age in the car waiting for that elusive break in traffic from both directions at the same time. I'm close to 50% EV. With a Prime, I'd probably be well over 80%.
     
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