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To Charge or Not to Charge(ever), that is the question...

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by mozdzen, May 7, 2012.

  1. mozdzen

    mozdzen Active Member

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    Someone brought up an interesting point the other day:

    If your electricity rates are high, and your gas mpg is very good, it is actually more expensive to charge up than it is to gas up.

    Example:
    10 cents per KWH for a PiP getting 14 miles per 4.4KWH
    That is 44 cents for 14 miles which means $4 gets you 127 miles

    If your electricity costs 25 cents/KWH, then your charge up will cost $1.10, meaning $4 of this gets you 51 miles.

    Now, if your Prius gen III or PiP is getting 60 mpg, you save no money by using electricity.

    Bottom line: the better the Prius is on gas mileage, the less sense it make to run it in EV mode from a pure dollars standpoint (ignoring the cost of fossil fuels, army cost to protect shipping lanes, and other effects that 97% of the population doesn't think about when buying a car)
     
  2. andyprius

    andyprius Senior Member

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    Good point, but my 12.2 V EV turns into 21 miles minimum. That will probably improve later as the car loosens up. I find that around my local suburbia my gasoline cost are next to nothing. Of course the concept behind owning any EV or hybrid is to lessen oil demand and to clean up the air. For the consumer, the carrot is the MPG.
     
  3. crewdog

    crewdog Acting Ensign Prius Prime

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    my last tank was 119.9 mpg

    my last measured kwh was 110 on the kill-a-watt, add in 15 for unmetered kwh at home and at public charge station for 125 kwh

    i pay about 11 cents/kwh after taxes, fees

    so my electric cost was about $13.75

    It's what that 12 or 14 miles of EV allows you to do that's the key; not a strict dollar for dollar formula. you might say that 12 miles of EV range is an exponential factor, not just an addition.

    I'm using less gasoline, and so is everyone else who charges i think. How much less is all subjective to terrain, personal driving technique, and other factors.

    Heck, i gotta go into quicken to see when i got gas last.
     
  4. rogerv

    rogerv Senior Member

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    Not sure about your figures. My PHEV (the proper name from elsewhere on PC) uses 3.0kWH (or slightly more), not 4.4, and returns 14-15 miles per charge of pure EV driving. My winter rate of $0.13 per kWH X 3 = $0.39, or roughly $0.027 per mile. OTOH, at 60 mpg, a $4.00 gallon of gas costs $0.067 per mile. When you factor in the recharging that occurs as you drive, the MPGe gets even better. I used a Kill-A-Watt to record the kWH and cost of each charge. Sometimes it uses 3.1kWH, sometimes just 3.0, but in any case costs about $0.40 max. So the $4.00 spent on charging would take me approximately 148 miles, as opposed to 60 miles on gasoline, without any regen while driving.
    Am I missing something?:confused:
     
  5. mozdzen

    mozdzen Active Member

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    Everyone who replied pays a nice rate for electricity. I've heard that NY and Ca have rates closer to the 25cents/KWH, maybe more if they charge during the day. And the point of my original post was to point out the interesting one-two punch-effect that high electricity rates like these coupled with awesome Prius mpg can have on the overall benefit of charging.
     
  6. mitch672

    mitch672 Technology Geek

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    if you are paying a high price for power, then it sounds like getting one of these: ClearEdge 5 | Home Fuel Cell | ClearEdge Power would reduce your cost for power, by a lot. Yes, this costs $56,000 to buy, but generates nearly 40,000 KWh/year, at a cost of about .10/Kwh, a side benefit, it also produces heat, which can be used to heat your domestic hot water, your pool, or used for a radiant heat system as well.

    P.S. They are comming out with a smaller, 2KW system, that would work on most houses, the 5KW system is for a fairly large home (4000 sq feet or larger)
     
  7. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    I pay $0.30/Kwh (until my new time-based rates kick in and I get a lower off-peak rate), so the cost per charge for me is just about $0.90. A full charge gets pretty close to the same range as 1 quart of gasoline (~ 12 miles), so if gasoline is above around $3.60/gal, I come out ahead. Currently, gasoline here is about $4.12/gal, so electricity comes out ahead right now. But it certainly is not a dramatic difference.
     
  8. fjpod

    fjpod Member

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    In NYC I pay roughly 25 cents per kwh. In the summer, we pay a little more especially if we go over a certain amount of usage. The NYC grid goes under great stress if we get more than three days in a row of 90 degrees F plus. con Edison starts alerting the media for residents to cut back.

    And although we do have the option to choose a time of use billing system where the rates are lower at night, the damn rates are higher than normal during the day. So it's rigged so you almost can't win.
     
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  9. ralleia

    ralleia Active Member

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    If my rates here weren't so low (~.11/kWh), I might be tempted. But for that kind of money, I'd dump it on a large solar array (or hybrid solar/wind) instead.

    I think there's a 30% federal tax credit on solar through the end of the year, too.

    Oops--my bad, I forgot our rates went up this year. After taxes it's now 13.3 cents/kWh.
     
  10. josh2008

    josh2008 Active Member

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    My rate here is $0.11 per Kwh after all the transmission fees and taxes are added in. Don't know where you 4.4kwh number comes from, my PiP takes 3-3.2kwh to fully charge. Car shows 15.9mi of EV estimated distance when fully charged, usually get 20-21mi. Plus, Monday - Friday normally all my charging is done at work, which they don't charge me for 8)
     
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  11. mitch672

    mitch672 Technology Geek

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    There is a $5K federal tax credit, and a $12.5K California rebate on the fuel cell system above, plus the waste heat can heat your pool, etc. this applies to Californians who are paying very high tiered usage rates, this can have a very short payback, assuming you use 120KWH/day or so.

    This also works 24x7, and has 11 times more energy production than an equivalent PV system (5KW)

    For places with very poor solar insolation (# of solar producing hours/day), this is also much more practical investment to lower your energy usage/footprint
     
  12. timdsd

    timdsd Junior Member

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    Can you tell us what kind of driving you do? A full charge for me is only 9.5 miles. Most of my driving is around a residential neighborhood, 25 - 35 MPH, lots of stop signs, a few hills (but nothing like San Francisco), no A/C or heat, and no hard acceleration.
     
  13. o2cool

    o2cool o2cool

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    I live in Palo Alto, which has some of the lowest electric rates in the Bay Area. However, with PG&E increasing rate tiers, there are many in the $.30/kwhr range. My recommendation, which I did even though we have low rates in PA, is to call Solar City or one of the other companies that will put solar panels on your roof with little or no upfront from you. If you can afford it, you might want to pay for the system anyway. This will have a very good payback, whether you plug in your new Prius or not. By the way, you might want to contact PG&E and see if they can give you time of day charging. Or contact the State PUC and ask they start implementing it. It makes huge sense for most of the EV charging to be done at night. The Prius already is equipped for this with the time. They should be charging no more than $.10/kwhr (maybe even lower) for electricity in the 10 pm to 6 am period. The new Smart Meters, which some people have been fighting, will enable the time of day pricing of electricity.
     
  14. bartleby

    bartleby New Member

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    Honestly, if it was just about saving money, we would have all opted for the standard Prius, not paid ~8k more pre tax credit

    Even if there is no price benefit to plugging in versus not depending on your local electrical pricing, there are still two good reasons to juice rather than gas:

    -Geopolitical reasons: electricity generated in the USA is made from fuel made here, not purchased from the despots and bad actors of the world.
    -Environmental reasons: Travel on electricity still generates less carbon than gasoline per mile in most places in the USA. This varies significantly by region (search for the article titled "How Green Are Electric Cars? Depends on Where You Plug In" at the NY Times")
     
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  15. jbrad4

    jbrad4 Active Member

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    4.4 kWh is the capacity of the Li-Ion battery, but only 3.1 kWh of this battery is usable for EV Mode. So, 3.1 kWh is the amount of energy required to charge a depleted battery.
     
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  16. usbseawolf2000

    usbseawolf2000 HSD PhD

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    So far, the owners are averaging 100 miles with 23 kWh of electricity. That may need 15% more to include charging loss, so 26.5 kWh.

    At that rate of electricity consumption, plugging in makes sense. With 25 cents per kWh, you can go 100 miles for $6.625. $3.312 for 50 miles.

    If the rate is 30 cents per kWh, it comes out to $4 per 50 miles. It would cost about a gallon of gas at 50 MPG.

    In term of emission, electricity in CA and NY are much cleaner than the average (11 cents/kWh) electricity. Nissan Leaf consuming 34 kWh/100 mile would emit 120 g/mile using CA or NY electricity. 50 MPG Prius would emit 222 g/mile (CO2e). Prius PHV at 26.5 kWh/100 mile should emit 94 g/mile when running on electricity.

    The cost can be the same for states with clean electricity but the emission would be much lower. For other states with "not so clean electricity", you'll save money to plug it in. So, yes plug it in!
     
  17. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    And then there is the Northwest with their 10cent/kWh hydro power, which is pretty much zero emission.
     
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  18. radiocycle

    radiocycle Active Member

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    Thanks bartleby and welcome to Prius Chat :welcome:
     
  19. Three60guy

    Three60guy -->All around guy<-- (360 = round) get it?

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    We must remember something pretty important. The charge "RATE" is about .9 kwh (point 9 kwh) per hour on the 110 volt charger. So, if you come home and still see half of your EV mileage still available (11 times .5 or 5.5 miles) it will take only an hour and a half (on 110 volts) to recharge to full. The cost to you of that would be RATE (in $) X .9kwh X HOURS.

    So for example I have time of day rates here in Wisconsin.

    After 7pm I pay $.047 per KWH.

    So, a filler up of 1.5 hours would cost me $ .047 X .9kwh X 1.5 hours or $.06 as my cost to recharge. Pretty sweet.

    We should not confuse the Rate of charge with the capacity of the battery.

    Cheers
     
  20. bayarea99

    bayarea99 New Member

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    That may be true. My rate is 12.7 cents, remember some of us get a free charges at work plus at least here in California there are still LOTS of free chargers around. So I probably only pay for 30% of my charges. Because of this, I have been running 80% EV and 20% HV. I am thinking this is probably not good for the battery, so I plan to run gas a little more.