Monthly Electricity Cost/MPG Equivalent

[N1ghtrider]

I am pleased to report that my electric bill for my first full month of Leaf ownership dropped from 2,685 KWh used in the same month the year before to 2,615 (I know it is a lot, but I have a big, leaky house in hot climate). At my average of 5.2m'kwh for 1,016 miles, I used 195.4 kwh for driving, or 7.5% of my total FPL bill. With all taxes and fees included, power costs 11.7 cents/kwh, so the Leaf charging cost was $22.86. That is 2.25 cents per mile.

Gas is expensive in Miami, so at an average price of $3.70 per gallon, I bought the equivalent of 6.18 gallons of gasoline for my $22.86 electric bill payment. Because I drove 1,016 miles on the equivalent of 6.18 gallons, I realized an equivalent of 164.4 miles per gallon.

These are numbers the public can relate to. What figures are others seeing in light of your m/kwh and local gasoline prices?

 

[fooljoe]

I recently looked at my 7 months of electric bills post-Leaf and compared them to the same 7 months from a year earlier and saw that I had a total increase of exactly $200, for a little more than 8000 miles of driving. Of course there are plenty of other factors that can affect my bill, but without a separate meter that's the best I can do. With gas now at $4/gallon around here, that's 160 mpg equivalent.

 

[GaslessInSeattle]

My cost has ranged between 2.2 cents to around 3 cents depending on time of year, it spiked when I started testing very long prewarming sessions. I just installed a hybrid electric heat pump hot water heater that stands lower our household electric bill enough to zero out about 10,000 miles of driving a year! the savings with EV's is so amazing it sounds outlandish, it's somewhere in the equivalent range of 50 cents to a dollar a gallon gas. Our first 12,000 miles cost around $300. I don't think the public has any idea of just how much an EV can save in gas. hybrids are very clean and somewhat more economical than regular gas cars but the return on investment takes a while whereas EV's have a vastly shorter return on investment and the Leaf is the only type of vehicle on the market today that stands to pay for it's self in it's lifetime in gas savings. At first I was worried about the battery replacement cost, but now that there are folks putting near 50K on this car without seeing any battery degradation, I'm optimistic that the battery will easily hit the 150 K mark before needing replacement, where ROI will approach the cost of the car after tax credit. IMHO, this kind of savings will have universal appeal, combine this savings with a DC QC network and a much larger portion of the public will get excited for this technology... oh, that and $5 a gallon gas. Looks like we might have a winner after all, come this summer!!!

 

[lpickup]

Is your 5.2mi/kWh battery to weels (what the car itself reports) or wall to wheels (based on actual electricity pulled from the grid). If wall to wheels I am amazed at your stats! There is some overhead (loss) through the EVSE and into the battery that you need to take into account.

For January my numbers are 400kWh for 1350 miles (3.38mi/kWh) even though I get about 3.8 inside the car.

Nonetheless, calculating that through I get $41.16 for those miles or just over 3 cents per mile. Gas is the same here right now so 11.12 gallons or 121.4 miles per gallon.

However, I've learned to really hate the "miles per gallon" measuring stick. If's a measure of EFFICIENCY, not ECONOMY and once the numbers get high, it quickly loses it's meaning. The difference in actual cost of fuel (and amount of fuel used) between a 10 MPG car and an 11 MPG car is exactly the same as between a 50 MPG car and a 100 MPG car: basically over 100 miles you will save 1 gallon of gas by doing each one of those upgrades.

Instead, a better measurement is gallons per mile (or the more convenient gallons per 100 miles). This directly measures CONSUMPTION (and therefore COST and ECONOMY) and is easier for people to directly translate to cost savings in their pocket.

So your 164.4 MPG translates to 0.61 gallons / 100 miles
My 121.4 MPG translates to 0.82 gallons / 100 miles
My old 24 MPG car translates to 4.17 gallons / 100 miles

So why is it better to think of it in these terms? Well, let's assume in a given time period (a week, 2 days, whatever) I travel 100 miles. Those numbers tell me exactly how much "gas" I'll have to buy to travel that distance. And by multiplying by the current price of gas by that number, I can also easily calculate how much it will cost me.

I can also directly compare relative costs of car A vs car B with these numbers. 4.17 - 0.82 = 3.35, so to go the same distance in my gas car I would use an extra 3.35 gallons. At $3.70/gallon, that's over $12 extra I have to pay to drive that far in my old car as it does my LEAF. You can't do that easily with MPG figures. In fact, as I said using MPG figures could be misleading: if you compare a 10 MPG car to an 11 MPG car, you'll get the exact same difference (1 gallon / 100 miles) even though intuitively you'd think that a jump from 10 MPG to 11 is no big deal but 50 to 100 is huge!

If I could learn to drive like you, I could save myself 0.21 "gallons" in that same time period. Efficiency is important, but what we really care about is economy. Efficiency is a way for car manufacturers to measure how good a job they've done in improving their engine's efficiency. We've been brainwashed to accept that as a "fuel economy" number, but it's not. Gallons/100 miles is a more practical way to measure that.

 

[DaveinOlyWA]

i use cost analysis based on mpg pricing. i run it against the highest gas car; the Prius. granted the primary driver of the Prius drives inefficiently so the mileage on average has dropped about 3-4 mpg when she took over but the differences are extreme and i guess i have to say that i will soon be averaging 200 mpg using your scenario

 

[lpickup]

P.S. You basically used an economy-based measuring system when you stated you got 2.25 cents / mile. (or $2.25/100 miles). No need to go any further if you were comparing to gas cars that were measured in gal/100 miles, other than to translate to gallons by dividing by the cost of a gallon of gas to convert to gallons: $2.25/$3.70 = 0.608 gallons / 100 miles)

 

[camasleaf]

I am pleased to report that my electric bill for my first full month of Leaf ownership dropped from 2,685 KWh used in the same month the year before to 2,615 (I know it is a lot, but I have a big, leaky house in hot climate). At my average of 5.2m'kwh for 1,016 miles, I used 195.4 kwh for driving, or 7.5% of my total FPL bill. With all taxes and fees included, power costs 11.7 cents/kwh, so the Leaf charging cost was $22.86. That is 2.25 cents per mile.

Gas is expensive in Miami, so at an average price of $3.70 per gallon, I bought the equivalent of 6.18 gallons of gasoline for my $22.86 electric bill payment. Because I drove 1,016 miles on the equivalent of 6.18 gallons, I realized an equivalent of 164.4 miles per gallon.

These are numbers the public can relate to. What figures are others seeing in light of your m/kwh and local gasoline prices?

I agree that people can relate better to your equivalent. No ICE driver ever calculates cents per mile.
I tell people: "If I was to buy gasoline with the money I spent on electricity, my car would have to get 160 mpg to drive the same distance."
And yes, same like you, I get between 150 to 170 mpg equivalent. The problem is when you charge (still free) away from home, but I only use QC-DC once a week at most, so no big impact.

 

[TNleaf]

I agree that people can relate better to your equivalent. No ICE driver ever calculates cents per mile.
I tell people: "If I was to buy gasoline with the money I spent on electricity, my car would have to get 160 mpg to drive the same distance."
And yes, same like you, I get between 150 to 170 mpg equivalent. The problem is when you charge (still free) away from home, but I only use QC-DC once a week at most, so no big impact.

I've been tracking my entire home's electricity useage since 2008 (when I moved in) and since I had the EVSE installed I've kept track of how much electricity has been used to charge my LEAF. I'm running into the issue of charging away from home and having no way to track it. I'm working with my building manager to get the logging on our EVSEs so I can track how much I am using at work (you'd think they would want to know, but I guess they realize it's only going to be less than $20 per month).

So right now, I can still give a figure of how much my LEAF is costing me to drive (practically zero $), but it's unrealistic to think I'll be able to charge for free for a long period of time.

 

[Roadburner440]

Is your 5.2mi/kWh battery to weels (what the car itself reports) or wall to wheels (based on actual electricity pulled from the grid). If wall to wheels I am amazed at your stats! There is some overhead (loss) through the EVSE and into the battery that you need to take into account.

That should be easy to do in a Leaf? In my Volt I have seen as high as 4.5mi/kwh wall to wheels (with 15% charging loss factored in).. Granted I do not see that everyday (usually 3.6-3.9mi/kwh wall to wheel), but I think the Leaf should be higher without dragging an ICE and gas tank along for the ride everyday. I did notice on my test drive the other day I only got 3.4mi/kwh estimated by the nav unit (the Volt does not give you this data so I manually compute it on an excel spread sheet everyday). Looking forward to summer where I get closer to 45-47 miles a charge, and can't wait to see what my new Leaf is capable of. Personally I am hoping for 5 or 6 mi/kwh on my commute, but that is based on my experience with the Volt.

To answer your original question gas prices in my area are about $3.83 for Premium here. I use that on my Volt since it actually does take gas unlike the Leaf. So I calculate my gas money saved a little differently, as I use the 36mpg average I would get in CS mode vs some static number for a car similar to the Leaf... I am at about 127mpg using the gas/electric amount conversion. I am at about $0.03/mi.. Using more quanititave figures I am at 27kwh/100mi which beats the EPA estimated 35mi/kwh. Granted I do everything I can to squeeze every bit of electrical mileage out of the car. At least with the Leaf I know I will be well within, and I won't have to fret using climate control. Not to mention having seat heaters for the first time in years.

 

[DesertDenizen]

I have had a photo voltaic system for years and it still supplies all my needs, so I guess I am driving about as cost free as one can. I average 5.8 miles/kwh, but Tucson is ideal, the valley is flat and I never use the heater.

 

[cdub]

I have had a photo voltaic system for years and it still supplies all my needs, so I guess I am driving about as cost free as one can. I average 5.8 miles/kwh, but Tucson is ideal, the valley is flat and I never use the heater.

I'm averaging 3.9...but I live in the hills. Downhill to work. Uphill back home. Plus I drive like a maniac.

 

[copdoc]

(Too many threads to search through)

I'd like to estimate my wall-to-wheels and have no monitoring ability at all, really, besides Carwings and the dash.

If I take the dash number (4.2 mi/kWh average), what loss would you guys expect? AV EVSE is about 15%?

100 miles/4.2 = 23.8 kWh / .85 = 28 kWh at NC rates of 10.18 cents per kWh in the winter plus tax = $2.85

Are there other efficiency losses I'm missing? (Yes, I know a Kill-a-watt or a separate meter would be more accurate, but that's not a choice. Besides, all I want is an economy from the dash.) Do you guys who have such monitoring have a percentage I can use that would be more accurate than 15% loss?

 

[walter]

I use my Leaf on a regular basis. Sometimes twenty miles a day and other times thirty or forty miles a day. I have had the car since 11/31 and currently have 2,600 miles. My electric bill for December was about ten dollars higher and my bill for January had barely any increase. I don't break it down the way most of you guys do but here is the bottom line. I have saved at least one hundred dollars a month in fuel costs and have spent about ten dollars a month in electric. My rate is about nine cents a kwh. I love this car.......... How can anybody who knows anything about anything say this type of technology can't work........... :roll:

 

[Roadburner440]

I'm averaging 3.9...but I live in the hills. Downhill to work. Uphill back home. Plus I drive like a maniac. [/quote]

Driving like a maniac in the Leaf must be different from the Volt. :lol: Granted I did not get in to the Leaf on my test drive the other day (I spent most of the time trying to figure out how to input nav data, and determine whether or not I was in the dreaded Eco mode).... Driving like a maniac in my Volt though involves putting it in sport mode, and then getting 2-2.5mi/kwh, and going very fast. :mrgreen: Our Leaf is going to be the family car, but good to know it still gets almost 4mi/kwh driving crazy. Best I saw on our drive the other day was 3.4mi/kwh driving on I-64, but we did have the whole family in the car going 65mph.

 

[garygid]

50 mpg in the Prius at $4 per gallon = 8¢ per mile.

At 4.1+ mi/kWh and Tier 3 (or 4?) e-fuel at 33¢ per kWh = 8¢ per mile.

 

[Roadburner440]

Wow... I pay $0.112/kwh.. So even at my Volt's worst of 2.33mi/kwh it still only cost me $0.06/mi. My average for the month of February though (well, since my last power bill) is 3.61mi/kwh with 726.9EV miles costing me $22.64@$0.003/mi...

If I was paying $0.33/kwh I am not srue what I would do.. It would actually make the Volt worse than our Prius, and put it in the $0.09/mi range on average. To think in Florida I though $0.145/kwh was bad....

 

[N1ghtrider]

Is your 5.2mi/kWh battery to weels (what the car itself reports) or wall to wheels (based on actual electricity pulled from the grid).

Battery to wheels. For the first 65 miles of this charge I am at still 5.8 m/kWh, as the weather is mild.

 

[Nekota]

(Too many threads to search through)

I'd like to estimate my wall-to-wheels and have no monitoring ability at all, really, besides Carwings and the dash.

If I take the dash number (4.2 mi/kWh average), what loss would you guys expect? AV EVSE is about 15%?

100 miles/4.2 = 23.8 kWh / .85 = 28 kWh at NC rates of 10.18 cents per kWh in the winter plus tax = $2.85

Are there other efficiency losses I'm missing? (Yes, I know a Kill-a-watt or a separate meter would be more accurate, but that's not a choice. Besides, all I want is an economy from the dash.) Do you guys who have such monitoring have a percentage I can use that would be more accurate than 15% loss?

If you charge to 10 bars the load demand from the wall using the L2 charger is 3900 watts at beginning and at the end of your charging cycle. Carwings will send a 'charging stopped' message when 10 bars completes and by setting your charge timer to start at a known time (e.g. midnight) then the time stamp on the Carwings message can be used to calculate the power into the car. You have to setup the Carwings to enable the charging message and have it sent to your email address. Finally, use the odometer for the miles or one of the trip meters for that extra 0.1 mile resolution and you have KWHr to a minute resolution (2 hrs is about 1% error). It appears the voltage variation into the LEAF charger is compensated by the LEAF charging system by adjusting the current to keep the power constant. The largest error I encounter with this technique is when I "preheat" the car. The charger is still using 3900 watts , some of it goes to the heater and some into the battery. You can get start and stop times from Carwings by enabling the Climate control messages just like the charging one and provided you don't use the climate too long the LEAF charging system stays at 3900 watts.

 

[lpickup]

copdoc, I can't remember: are you on the Progress Energy plan? If so, you can get web-based monitoring through AV.

I SHOULD be able to calculate a simple "loss" type of figure, but I think it may take some work and thought.

At any rate I just checked a recent charge log and came up with an average of 3783 watts average (18.22 kWh over 289 minutes) so pretty close (but not quite as high) as Nekota's figure.

It would be easy to get a wall to wheels figure there from that, but to get a loss figure I'd have to reset the in-car efficiency monitor and back-calculate how much power the car thinks the motor consumed.

 

[ttweed]

My EVSE is on a separate meter, so I receive an itemized billing of the exact cost to charge the Leaf each month. We have pretty consistently averaged $25/mo. in electricity to drive 1,000 miles, so 2.5 cents per mile is a good estimate for us, which I also translate for my ICE-driving friends into "160 mpg if gas is at $4/gal."

TT