How efficient is the Clarity PHEV in converting gasoline into electricity?

Discussion in 'Clarity' started by BrianRC, Nov 28, 2023.

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  1. This must have come up in the past but I can't find it. Does someone know if there is a formula that equates kilowatt hrs. per galon of gasoline when running the Clarity in HV Charge mode? Sometimes when I am on a longer trip electricity can be pretty expensive on the road. I wonder sometimes when I have time to plug in but power is going for 35 to 50 cents per Kw/hr, I wonder if I am just better off using $4/gallon gasoline. TIA.
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  3. ClarityDoc

    ClarityDoc Active Member

    HV charge is a less attractive option on a long trip than driving in HV mode; the latter should maintain LOC ~50% under average conditions. That way, I don't need to charge on the road.

    The biggest problem with this scenario is that the Clarity "forgets" I want to stay in HV mode and reverts to default mode (mostly EV) after a stop.

    Your question about the efficiency of the generator is interesting to me though, so I'll be interested to see whether someone reminds me of a link to a previous thread about this.
  4. Robert_Alabama

    Robert_Alabama Well-Known Member

    I'd answer your question this way...

    As a choice as to running in HV mode versus charging the battery to get battery miles:
    At $0.35/kWh, and assuming you add 3.5 miles for each kWh for that $0.35, and if you think you get 40 mpg on gas, then multiply $0.35/kWh by 40 mpg divided by 3.5 miles/kWh to get $4.00 per gallon. At $0.50/kWh, this goes up to $5.7 per gallon.

    We've had a lot of discussion here on just how economic HV charge can be, but I'd say that generally you don't improve on average fuel economy by using it. Lets say that mpg drops to 30 mpg when using it for the miles added to the battery. Then the $0.35/kWh equates to $3.00/gallon of gas for HV charge as a breakeven and the $0.50/kWh equates to $4.25/gallon for choosing to charge the battery with electricity vs HV Charge use. If you believe you can use HV Charge without an efficiency hit, then the $/gallon calculations just go back to what I gave first.

    At 45 mpg as the assumption for gas economy, then multiply the $/gallon prices calculated above by 45/40 or increase them by about 10%.
    Last edited: Nov 28, 2023
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  5. MrFixit

    MrFixit Well-Known Member

    In my experience (mix of highway and 'city', and not in the dead of winter),
    I get more like 4 miles / kWh in EV, and 45 mpg in HV mode.
    Therefore, the equivalency is this:

    1 gallon will give you 45 miles,
    In EV, this would take 11.25 kWh [45 miles / (4 mi / kWh)]

    if your electric cost is $0.50 per kWh, it would cost you $5.63 [11.25*$0.50] to go the same distance as 1 gallon of gas
    if your electric cost is $0.35 per kWh, it would cost you $3.93 [11.25*$0.35] to go the same distance as 1 gallon of gas
    If your electric cost is $0.15 per kWh, it would cost you $1.69 [11.25*$0.15] to go the same distance as 1 gallon of gas

    So, with your scenario, you are better off using $4.00 per gallon gas if the price of electricity exceeds ~$0.35 per kWh.
  6. .

    A gallon of gas is equivalent to 33.4kWh’s. The most efficient gas engines can convert about 40% of that (13.36kWh’s) to electricity. The Clarity is capable of charging the battery to 60%, up to 12 bars, while in HV Charge. That gain of 10 bars from 2 to 12, represents about 7.5kWh’s of charge and will use about 6/10ths of a gallon of gas. At freeway speeds those 7.5kWh’s might net about 22 miles of forward progress. Or about the same as if you’d just used the same gas to propel the car. Why? Because the engine is about 40% efficient at that task as well.

    The elephant in the room here is, why would you spend time, up to 2 hours, plugging in the car to charge, at any price, on a long road trip?
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  8. Thanks @Landshark. That answers my question. At that ratio -- 1gal to 13.36 kWh’s -- assuming $4 gasoline that would equate to 30 cents per kWh. Out here in California, most ChargePoints are 35 cents per kWh, so even if I have the time to top off while I am having a meal, for example, it wouldn’t be cost effective.

    My intuition is that when I am going into an urban environment it is most economical to run on EV only, so best to top off the battery on the way in.
  9. I’ve always just operated the car in HV Mode on long trips and the battery gauge has never lost more than 3-4 bars. Even on 700 mile drives in 10 hours with multiple fuel and pee stops. That’s not low enough for HV Charge to activate.
  10. Good to know.
  11. neal adkins

    neal adkins Active Member

    It takes my clarity about 25 to 30 minutes (at highway speeds) in hv charge mode to go from zero range ( 2 bars) to hv charge complete. My fuel economy drops to 28 mpg for about 28 miles of driving to do the charge. So i used about 1 gallon of gas for the 28 miles and have 24 miles ev range. Thats 52 miles vrs the 40 mpg on just staying in hv mode. So i use hv charge alot when in road trips. This doesn't apply to extreme cold or hot conditions
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  13. PriusGeek

    PriusGeek Member

    I've taken many long-distance trips in my 2018. Usually between Texas and Wisconsin and once from Texas to Boston. I always make sure my batteries are fully charged before I leave and put it in HV as soon as I get to the highway. If I can, I try to get at least some charge from public stations if the battery gets below half or so. The only reason I've ever put it in HV charge is when the battery is fully depleted. It is not a pleasant experience driving the Clarity at 75mph with no battery! Trust me, the noise will drive everyone in the car crazy. I do everything I can to avoid that condition, but when it does happen, I usually put it in charge mode and suck-up the annoying noise for a half hour or so until I get enough battery back to return to HV without the noise. YMMV!
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  14. ClarityBill

    ClarityBill Active Member

    Seems like you are describing 'angry bees'. My car had the bad noise when it was new, but using high-octane gas eliminated the noise. I used high-octane gas for several thousand miles and the noise was gone. I switched back to regular gas, and the noise did not return.

    (People that have not experienced angry bees will not understand. Not all Clarity's are that noisy. I currently have 220,000+ miles, and I drive alot at 75 mph.)
  15. Would that 28 mile EV Range Estimate actually provide 28 miles at freeway speeds?

    In my experience, depending on the speed, it may only yield 20-22 miles. If you actually use the EV range, both sources of stored energy are being depleted.

    As a matter of personal preference, I like to keep the battery as fully charged as possible on road trips, in case I want to push the limits of the 7 gal gas tank. Or, if there is a need for low speed driving in EV Mode at a destination, I’d rather have 40-45 miles of range upon arrival as opposed to arriving with a partially or fully depleted battery.
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  16. neal adkins

    neal adkins Active Member

    I meant that i may travel 28 miles in charge mode at highway speeds to gain about 24 miles ev range. Actual gain will vary. Sometimes its around what you get at 22 miles of range gained. In my area I'm not using much heat or ac now so ev range is a little higher.
  17. Indeed, that is what you said. I used the miles traveled number rather than the EV miles gained number.

    To be clear, I don’t gain 22 miles of EV range, since I don’t follow the practice of using HV Charge on long trips. What I intended to convey was that an estimate of, let’s now say 24 miles, would actually yield fewer miles at freeway speeds. Perhaps less than 20 miles, since the estimate is based on previous drives, which were probably driven at slower speeds.
  18. neal adkins

    neal adkins Active Member

    I do about the same. Mostly use hv charge only before a long up-grade or when i need some ev range when i get to the city.
  19. Unless I’m missing something here, we don’t “do about the same”. I don’t deplete the batteries on a long trip to the point where HV Charge can be engaged. That’s pretty much the opposite of how you’ve described using the vehicle on a long trip. Either method will get us to our destination. They are just 2 different ways of achieving the same goal.
  20. neal adkins

    neal adkins Active Member

    No biggie....i was just referring to the20 - 22 range you said you got.

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