Another theory for HV-charge vs HV

Discussion in 'Clarity' started by Walt R, Oct 26, 2019.

  1. Agzand

    Agzand Active Member

    I have pushed my Clarity to the brink! I have seen those type of RPMs on several occasions. It most often happens at high elevations (above 7000 ft) and low speed roads. Trying to go faster than 45 mph, so gear mode can be engaged helps sometimes.
  2. David Towle

    David Towle Active Member

    The heater should have NO impact during HV Charge mode once the engine is warm (5 minutes) and providing hot water. It could have some impact during HV operation since the engine is not running constantly and you could run out of hot water on a long downhill in cold weather.
    insightman likes this.
  3. The Gadgeteer

    The Gadgeteer Active Member

    It is my understanding the Clarity doesn’t use engine heat except in extreme low temperatures like 15F (or was it 5F) and below.

    so anyway it is also my understanding that gear mode will engage only when the engine rpms can be such that it can maintain the HV preset charge level.

    however, I fully concede there is much about our Clairtys I do not know.
    Last edited: Mar 18, 2020
  4. The vehicle will attempt to maintain the battery SOC (EV Range) that was present at the time HV mode was activated. There are several means of propulsion while in HV mode.

    The ICE can provide electricity to the traction motor.
    The ICE and the batteries can provide electricity to the traction motor.
    The ICE can drive the front wheels directly, this is occasionally referred to as Direct Drive.
    In HV mode the car can also revert back to EV mode for brief periods of time.

    While all this is going on, the vehicle will use its best judgment to maintain the SOC. It may lose a few miles of range while going up hill for several miles. Let it be, and after the road flattens out it will restore the lost range.

    Direct Drive may engage at a low speed of ~45mph. I have witnessed it remaining in Direct Drive up to 85mph. It may or may not attempt to charge the batteries a bit between those speeds and RPM’s.

    Direct Drive does tend to disengage if more than 3 or 4 gerbils of power are requested from the right foot
    David Towle likes this.
  5. David Towle

    David Towle Active Member

    Where did you get this understanding from? Any evidence you can offer?

    Everything I have read and observed on the car says your understanding is incorrect.
    For example, to avoid using electric heat I always start out with the temp on low. After 10 minutes I turn it to 70. Within 5 seconds I feel significant heat, evidence to me that the heat is just sitting there in the water heated coil waiting for the damper door to move and let it out. We rarely get as cold as 15 F here. Electric heat would take significant time to ramp up.
  6. KentuckyKen

    KentuckyKen Well-Known Member

    Although I rarely use HV and so therefore I am absolutely NOT an HV expert, I have to agree w @David Towle. When in EV in the winter, using only the immersion resistance element, the heat comes on faster than my old gizzoline CR-V, but not 5 seconds fast. More like a minute plus or so. So that lends credence to his theory.
    David Towle likes this.
  7. The Gadgeteer

    The Gadgeteer Active Member

    An electric heater with a couple of thousand watts of power in a small liquid core could heat up in seconds. I get heat in seconds as well with a cold engine that hasn’t even started but that doesn’t mean the Clarity doesn’t use engine heat if available.

    Not sure if this is the original article I read but it is very good. Rereading this article it doesn’t actually say the car will *only* use ICE heat at 14F and below just that it will use it. So you might be that if ICE heat is available it might be used to heat the car. In fact it makes sense.
    The link to the whole article:

    here is the pertinent section:
    Unlike the Clarity Electric and Fuel-Cell cars, the Clarity Plug-In Hybrid has an ICE to generate heat (hmmm, heat from ICE doesn’t sound quite right, does it?). When the temperature dips to 14°F or below, the ICE starts up so it can warm passenger compartment (and the batteries below the seats and rear floor).

    To provide cabin heat while travelling on battery power when the ambient temperature is above 14°F, the Clarity Plug-In Hybrid provides resistive (electric) heating, as do its two ICE-less siblings. Of course, when you divert battery power to make heat, your all-electric mileage will vary—and not in a positive way. So the Clarity Plug-In Hybrid can alternatively use hot water from the ICE to warm the occupants when the ICE is running. The Clarity Plug-In Hybrid's resistive heater actually heats water that's sent through the same in-cabin heater core that the ICE uses.

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