HV Charge Mode efficiency question

Discussion in 'Clarity' started by Rick2112, Oct 7, 2018.

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  1. I am planning on needing to use the ICE a bit more in the coming months, and I am wondering if anyone has insight/information/knowledge about the efficiency (or inefficiency) of the ICE when charging in HV charge mode.

    Specifically, does anyone have any idea how many kWh are generated, for example, per gallon of gasoline? Also, does the ICE charge the battery at a constant rate, or is it variable, for example, based on the speed you are driving or other factors? Any other tips for driving in HV charge mode?

    Thanks in advance.
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  3. jdonalds

    jdonalds Well-Known Member

    All I can tell you is on a flat straight road at near sea level the MPG drops from about 43 to about 33 when I switch the HV Charge on. It has taken about 25 to 40 minutes to charge from 2 bars to 58%.
    Last edited: Oct 7, 2018
  4. neal adkins

    neal adkins Active Member

    If you use hv mode the current soc will be maintained (approximately). I only use the hv charge mode before going up a long grade or to prepare for low speed driving. When in hv charge I do think the charge rate changes depending on ice speed and power demand.
    insightman likes this.
  5. Eddgie

    Eddgie Active Member

    Running in HV Charge mode is very inefficient. It is far more efficient to run in HV mode.

    Think of it this way.. The 1.5L engine in the Clarity is one of the most efficient gas engines ever made, but it is still only 40% efficient. Then there is the conversion loss from the generator and the charging circuit. This means that putting in a KW of charge is going to destroy fuel economy.

    If you think you are going to need to run in HV mode, it is far better (in my own opinion) to just start in HV mode, or as Honda recommends, use HV mode as you get on to the highway.

    There really is no benefit at all to using HV Charge Mode other than maybe putting in a couple of bars before having to go up a long, steep climb.

    In HV mode (not HV charge mode) the car will run with ICE in direct drive much of the time, but you can see the generator to try to keep the battery at about where it was when you went into HV mode. Remember, the batteries have to run the environmental, entertainment, and car systems (electric assist on steering, etc). This means that in HV mode, the generator will have to come on frequently to maintain the battery charge, and when this happens, if you are using the instantaneous MPG readout, depending on your speed, you will see the MPG readout drop to between 38 and 44 MPG, but then as the battery does reach the state of charge that it had when you went into HV mode, the generator will cut off and the mileage will go back to 199.9. On a drive, it will simply do this, alternating back and forth between 40ish an 199,9 MPT as the generator is utilized to keep the battery at whatever state of charge it was in when you pressed the HV mode button.

    From an energy use standpoint, HV Charge Mode is about as bad as it can get, so I would say that you would want to avoid it if at all possible. If your trip is such that you will deplete the battery, it is just batter to go directly into HV mode when you have maybe 5 or 6 bars left, and this conserves a bit or battery for traffic or hills or acceleration needs. Don't HV Charge the car if it can be avoided. Mileage is horrible in HV Charge mode.
    Kailani and insightman like this.
  6. Hey guys, as always, many thanks for the great advice.
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