Dollar Cost of EV vs. Fuel

7264 Views 60 Replies 26 Participants Last post by jcanoe, Jun 8, 2017

JRRF

Discussion Starter · Jun 2, 2017

With all charges, I pay about $0.15/kwh. Gas in my area is about $2.40/gal. I'm not sure where they get 100 MPGe, but my calculation says that in EV mode, on a cost basis I'm only getting the equivalent of 60 MPG. That makes the gas engine damn near as efficient as the battery. Did I do something wrong in this calculation?

53 miles/14kwh = 3.8 miles/kwh = 3.8 miles/$0.15

$2.40/$0.15 = 16 kwh/gallon

16 * 3.8 = 60 miles/(dollar equivalent of gas)

1 - 20 of 61 Posts

skiflyer

· #2 · Jun 2, 2017

Just didn't finish it, you're getting 60 miles for the same cost as a gallon of gas. I'm guessing you're getting about 40 miles for an actual gallon of gas. So that gives you 50% improvement per dollar spent. Insert your actual mpg into the calculation.

Then the bigger issue... It's $2.40 today, what will it be in August? Cost of electricity is much more stable.

Sent from my Nexus 6P using Tapatalk

PrivatePilot

· #3 · Jun 2, 2017

x2 above.

For us here in Ontario it's a no brainer - off peak electricity is $0.075c/KWH but gas is roughly $1.15/L right now, or $4.35/Gallon.

Even at our significantly higher mid and on peak electricity rates it still wins vs gas.

Needless to say, for those who own EV's and understand the math, we are laughing. Sadly there's still so much misinformation out there that it makes me want to bang my head into the wall sometimes - many still think that "Gas would be cheaper than the electricity!".

jsmay311

· #4 · Jun 2, 2017

MPGe has nothing to do with the cost of fuel. A simple google search could've told you that.

Aside from that, your calculations are wrong too. You can't just divide 53 miles by 14 kWh. That doesn't take into account charging losses. The correct figure to use is the EPA rating: 0.31 kWh/mile or 3.2 mi/kWh.

Sean-a-Tron

· #5 · Jun 2, 2017 (Edited)

It's easier to break it down to cost per mile.

Assuming the Volt's rated 40MPG with $2.40/gal

Gas: $0.06/mile

Assuming the Volt's usual 4miles per kWh

Electric: $0.032/mile (Assuming 15% loss during charging)

JRRF

Discussion Starter · #6 · Jun 2, 2017

jsmay311 said:
MPGe has nothing to do with the cost of fuel. A simple google search could've told you that.

Aside from that, your calculations are wrong too. You can't just divide 53 miles by 14 kWh. That doesn't take into account charging losses. The correct figure to use is the EPA rating: 0.31 kWh/mile or 3.2 mi/kWh.

That only makes the comparison worse. At that rate I'm only getting 51 miles/(dollar equivalent of gas). And the engine can get close to 50 as well.

I'm looking into getting timed based billing from the power company, but if you don't drive that much (and don't have to fully charge your battery every night) there is no real advantage because they also charge you more than normal during peak hours.

jcanoe

· #7 · Jun 2, 2017 (Edited)

Chevy estimates the Volt's EV range at 53 miles. To charge the Volt takes an estimated 16kwh (14kwh + 2kwh for charging losses.) 16kwh * $0.15 per kwh is $2.40 for a full charge. $2.40 / 53 miles = $0.045 per mile when in EV mode. As your stated, gas is approx. $2.40 per gallon. The Volt is EPA rated at 42mpg (combined city and highway) when using gas. $2.40 / 42 miles = $0.057 cents per mile. So the cost per mile in MD is close, at current gas prices it costs about 1 cent more per mile to use gas than electricity.

On an absolute basis, electric motoring in the Volt is almost 4 times more efficient than driving a conventional vehicle using gas. To start, the gallon of gas energy equivalent in kwh is approx. 33,700 kwh. The Gen II Volt is EPA rated at 106 MPGe (combined). If the Volt had a 33.7kwh battery you would expect to be able to travel 106 miles but it only has ~14kwh available battery (not including any range due to regen) and Chevy estimates the Volt's EV range at 53 miles. Today the average passenger vehicle achieves 27mpg (combined) but much less for an SUV or a truck. So dividing 106/27 you get 3.92. If you are comparing the Volt in EV mode to a Prius hybrid using gas that gets 54mpg then the Volt in EV mode is about 2x as efficient as the Prius. Comparing the Volt in EV mode to the Volt when using gas is 106/42 = 2.5 times more efficient when in EV mode. Compared to a Prius @ 54mpg the Volt's cost effectiveness is the same , maybe slightly less than the Prius, but only until gas prices rise.

If you were to charge a 33.7 kwh battery at $0.15 per kwh (not counting charging losses) it would cost $5.05, more than twice as much as the gallon of gas would currently cost but because the Volt is 4x more efficient at using that energy (a conventional gas engine loses 75% of the energy contained in a gallon of gas as heat and friction) the Volt is still twice as cost efficient per mile as a vehicle that gets 27mpg with gas at $2.40 per gallon. As gas prices go up the Volt only becomes more cost effective.

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JRRF

Discussion Starter · #8 · Jun 2, 2017

Sean-a-Tron said:
It's easier to break it down to cost per mile.

Assuming the Volt's rated 40MPG with $2.40/gal

Gas: $0.06/mile

Assuming the Volt's usual 4miles per kWh

Electric: $0.032/mile (Assuming 15% loss during charging)

Much simpler for sure!

JRRF

Discussion Starter · #9 · Jun 2, 2017

jcanoe said:
Chevy estimates the Volt's EV range at 53 miles. To charge the Volt takes an estimated 16kwh due to charging losses. 16kwh * $0.15 per kwh is $2.40 for a full charge. $2.40 / 53 miles = $0.045 per mile when in EV mode. As your stated, gas is approx. $2.40 per gallon. The Volt is EPA rated at 42mpg (combined city and highway) when using gas. $2.40 / 42 miles = $0.057 cents per mile. So the cost per mile in MD is close, at current gas prices it costs about 1 cent more per mile to use gas than electricity.

That makes it even less of an issue to worry about what mode you might be in. Just go.

PrivatePilot

· #10 · Jun 2, 2017

JRRF said:
I'm looking into getting timed based billing from the power company, but if you don't drive that much (and don't have to fully charge your battery every night) there is no real advantage because they also charge you more than normal during peak hours.

If you're paying a flat rate of $0.15/KWH now and you can half (or better) that by going to a time of use system, well, charging your Volt is only the beginning of potential significant savings. Our off peak starts at 7PM, which not coincidentally is when our Volt is programmed to start charging, our pool pump switches on to go into it's nightly filtration cycle, we start our dishwasher, washer, and dryer, all of which have time delay functions that we sometimes use to accomplish such, but even if not, doesn't really constitute a hassle.

Needless to say, our house ends up drawing between 4 to 6 Kilowatts per hour for several hours post 7PM, but we're doing it on MUCH cheaper electricity than if we were we on flat or tiered rate.

So, long story short, if the off peak starts at a favourable time like ours does, and you are willing to make some minor tweaks to your lifestyle to accommodate the potential for very real savings, well...you CAN lower your electricity bill by a not insignificant amount by going to TOU metering.

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llninja

· #11 · Jun 2, 2017

Here's an even worse scenario. At work there is an L2 Chargepoint station that charges $2 per hour for the first 4 hours and $8 per hour after that, to free up the space for the next person. Even though this is horribly worse than the price of gas, I'm going to do it anyway to give OPEC the middle finger. When the house is completely paid off, I'll be charging daily instead of occasionally while saving pennies for the next longer range EV.

Makes your electricity seem downright cheap now, doesn't it?

JRRF

Discussion Starter · #12 · Jun 2, 2017

jcanoe said:
On an absolute basis, electric motoring in the Volt is almost 4 times more efficient than driving a conventional vehicle using gas. To start, the gallon of gas energy equivalent in kwh is approx. 33,700 kwh. The Gen II Volt is EPA rated at 106 MPGe (combined). If the Volt had a 33.7kwh battery you would expect to be able to travel 106 miles but it only has ~14kwh available battery (not including any range due to regen) and Chevy estimates the Volt's EV range at 53 miles. Today the average passenger vehicle achieves 27mpg (combined) but much less for an SUV or a truck. So dividing 106/27 you get 3.92. If you are comparing the Volt in EV mode to a Prius hybrid using gas that gets 54mpg then the Volt in EV mode is about 2x as efficient as the Prius. Comparing the Volt in EV mode to the Volt when using gas is 106/42 = 2.5 times more efficient when in EV mode. Compared to a Prius @ 54mpg the Volt's cost effectiveness is the same , maybe slightly less than the Prius, but only until gas prices rise.

This just sounds like an analysis of how cheap gas is per energy density.

JRRF

Discussion Starter · #13 · Jun 2, 2017

PrivatePilot said:
If you're paying a flat rate of $0.15/KWH now and you can half (or better) that by going to a time of use system, well, charging your Volt is only the beginning of potential significant savings. Our off peak starts at 7PM, which not coincidentally is when our Volt is programmed to start charging, our pool pump switches on to go into it's nightly filtration cycle, we start our dishwasher, washer, and dryer, all of which have time delay functions that we sometimes use to accomplish such, but even if not, doesn't really constitute a hassle.

Needless to say, our house ends up drawing between 4 to 6 Kilowatts per hour for several hours post 7PM, but we're doing it on MUCH cheaper electricity than if we were we on flat or tiered rate.

So, long story short, if the off peak starts at a favourable time like ours does, and you are willing to make some minor tweaks to your lifestyle to accommodate the potential for very real savings, well...you CAN lower your electricity bill by a not insignificant amount by going to TOU metering.

I'm still looking into doing this, but the data is hard to come by. I can view my hourly usage, but can't download the data into a spreadsheet. Yes, the off-peak rates are lower, but as a trade off my power company then charges you more for the peak rates. Instead I now pay somewhere in the middle for all my energy.

JRRF

Discussion Starter · #14 · Jun 2, 2017

llninja said:
Here's an even worse scenario. At work there is an L2 Chargepoint station that charges $2 per hour for the first 4 hours and $8 per hour after that, to free up the space for the next person. Even though this is horribly worse than the price of gas, I'm going to do it anyway to give OPEC the middle finger. When the house is completely paid off, I'll be charging daily instead of occasionally while saving pennies for the next longer range EV.

Makes your electricity seem downright cheap now, doesn't it?

What it says to me is that if you ever have to pay more than pennies to hook-up, just use gas. Leave the charging stations for the BEVs who have no choice.

KenC

· #15 · Jun 2, 2017

JRRF said:
With all charges, I pay about $0.15/kwh. Gas in my area is about $2.40/gal. I'm not sure where they get 100 MPGe, but my calculation says that in EV mode, on a cost basis I'm only getting the equivalent of 60 MPG. That makes the gas engine damn near as efficient as the battery. Did I do something wrong in this calculation?

53 miles/14kwh = 3.8 miles/kwh = 3.8 miles/$0.15

$2.40/$0.15 = 16 kwh/gallon

16 * 3.8 = 60 miles/(dollar equivalent of gas)

Your Moroney sticker gives you the mfrs' assumptions. Something like 13c/kWh, and $3 gas.

accelerus

· #16 · Jun 2, 2017

even with our cheap gas in TX im still doing very well on the savings aspect.

right now gas is hovering around $2.25, I only pay 8 cents per kwh.

of course the level of savings is dependent on how much you drive in full EV mode, I do 75 miles a day round trip with no charging at work

Raymondjram

· #17 · Jun 2, 2017 (Edited)

Sean-a-Tron said:
It's easier to break it down to cost per mile.

Assuming the Volt's rated 40MPG with $2.40/gal

Gas: $0.06/mile

Assuming the Volt's usual 4miles per kWh

Electric: $0.032/mile (Assuming 15% loss during charging)

This is the only correct way to calculate your expenses: cost per mile. You can lower it by driving carefully (to improve efficiency), charge for free when ever possible, buy cheaper gasoline, or do all three.

Not covered here is the reduced engine maintenance if you drive more in EV mode than with gasoline. I know a Ford Fusion Hybrid owner who drives carefully, and has spent only $40 a year in engine maintenance, not covering gasoline, because he is proactive, sometimes hypermiling when possible. Do you know anyone else that can spend $40 or less a year? Only a hybrid or an EREV can do as good or better.

froggert

· #18 · Jun 2, 2017

Cost for my daily commute:

Gas is $2.40/gallon and I'm getting ~46 mpg (all highway): 5.2 cents/mile
Electricity is $0.185/KwH: 5.58 cents/mile

This is using today's numbers, so during the winter running on electricity costs me almost 7 cents/mile.

alfon

· #19 · Jun 2, 2017

Gas $2.50 / gal and electricity .20 / kwh x 16 (kwh for full charge w/ charging losses) 45mpg avg on gas. cost to drive
55 miles full electric charge $3.20 / Cost on gas $3.05 for 55 miles @ 45 mpg.

So it looks like .20 KWH or more it is probably less cost per mile on gas, if gas is $2.50 / gal.

JRRF

Discussion Starter · #20 · Jun 2, 2017

froggert said:
Cost for my daily commute:

Gas is $2.40/gallon and I'm getting ~46 mpg (all highway): 5.2 cents/mile
Electricity is $0.185/KwH: 5.58 cents/mile

This is using today's numbers, so during the winter running on electricity costs me almost 7 cents/mile.

alfon said:
Gas $2.50 / gal and electricity .20 / kwh x 16 (kwh for full charge w/ charging losses) 45mpg avg on gas. cost to drive
55 miles full electric charge $3.20 / Cost on gas $3.05 for 55 miles @ 45 mpg.

So it looks like .20 KWH or more it is probably less cost per mile on gas, if gas is $2.50 / gal.

So on a daily basis, gas needs to get quite a bit more expensive to make EV driving more than a cool tech toy. Especially if your electric supplier is burning mostly coal.

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