Are my calculations wrong? KWH costs, total charging costs

[Hickey]

Hi Everyone,

 

new owner here, bought a 18 FFE in july

 

I've been trying to track my KWH usage, and i'm not certain if my math is sound.

 

from the window sticker, it shows 21.5KWH/100km, but i'm likely reading it wrong since its got that combined with gas saying 2.4L/100km

 

Am I to believe that every time I charge my car its 21KWH of usage? so off peak it costs me 1.40 CAD daily to charge my car for 30KM range? 

 

Someone please tell me i'm wrong, its the equivilant to gas if thats the case, which makes no sense.

 

Any help would be appreciated!

[murphy]

The battery is 7.6 kWh.  Only 5.6 kWh of it is available for electric drive mode. Charging efficiency is around 80% so 5.6 / .8 = 7 kWh to charge. 

 

It looks like your electric rate is 1.40 / 21 = 7 cents CAD per kWh.   7 kWh * 0.07 = 0.49 CAD to charge the battery.

 

I have 10 kW of PV solar panels on the roof of my house.  In the summer my cost for electricity is about $0.008 US per kWh.  That's $0.06 US to charge the battery.

[jsamp]

Even with my 'outrageous' ~24¢/kWh (CA prices) it only costs me  ~$1.30 to charge, and that typically gets me ~24 miles, so 5.4¢/mile.

[jj2me]

Even with my 'outrageous' ~24¢/kWh (CA prices) it only costs me ~$1.30 to charge, and that typically gets me ~24 miles, so 5.4¢/mile.

Forgot to divide by charging efficiency (.72 L1, or .80 or whatever L2). That would be $1.80 L1.

[RickEnergi]

If gas is $2.50, and the car gets 42MPG on gas, that's a cost of 5.95 cents per mile.

 

We pay 11.5 cents per kWh at off peak, 22.0 cents peak.  7 kWh to charge fully = 80.5 cents, divided by 21 miles = 3.83 cents per mile for off peak, and 7.33 cents per mile for peak.  So unless gas goes up, for us charging at off peak is the only thing that makes sense.

 

We put on roughly 7,500 miles a year.  At $2.50 per gallon, that would be roughly $450 in gas.  At off peak rates, with 40% EV and 60% gas mode, we'll spend around $385 per year.  Savings are really irrelevant at low miles driven, or at combination EV and gas driving, or when gas is this low.

 

We bought this over the hybrid because it was thousands less due to Ford's rebate and tax credit (built into lease).  And cheaper than the gas model we would buy (2.0 liter turbo).  Savings are not much.

 

We owned a 2010 hybrid for 8 years.

[jsamp]

Forgot to divide by charging efficiency (.72 L1, or .80 or whatever L2). That would be $1.80 L1.

 

If gas is $2.50, and the car gets 42MPG on gas, that's a cost of 5.95 cents per mile.

 

Both good points.  With my gas prices of ~$3.70/gal right now (ain't CA life grand!) I'm still money ahead on electric.  Not much, but ahead.

[bdginmo]

The charging efficiency on 120v and 240v is about 72% and 82% respectively from what I was measuring.

[rbort]

I use 120v at home always and only.  Would never invest in a 240v at home.   240v on the road is free for me.  At home you can put a kill a watt meter on it:

 

https://www.amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU/ref=sr_1_4?ie=UTF8&qid=1543272934&sr=8-4&keywords=power+meters

 

To see how many kwh you take to recharge the car.  

 

Buying a 240v for home usage could get you into trouble.  It allows for quick recharging which means you may tend to make more in and out trips and recharge in between.  That in turn makes for a hotter battery back and more degradation over time.  240v at home is a double edged sword... :)  And don't expect that 240v efficiency over 120v is going to save you any money.  The money you spend to install it will never be recooped by the 8% efficiency savings that are claimed.

 

My electricity is also free at home due to solar panels, but in reality its not free as I get less credit on my bill when I charge more.  Credit I can use in the cold dark winter months so to speak.

 

-=>Raja.

Edited November 26, 2018 at 10:59 PM by rbort

[Mr.Fusion]

These numbers are based on the usage reported by a "pay per kWh" Level 2 charging station at one of my sites.

 

Started at "0%" and charged to full.  Car is only a few weeks old, so it's still "learning", perhaps?

 

It took 3.25kW for 2.5 hours, not counting that taper off in the last few minutes:

 

 

Total power "delivered" was 7.01kWh.  According to MyFord Mobile, capacity used on the way home (again, went back to "0%" before switching to hybrid mode) was 5.5kWh, so that yields only a 78% charging efficiency.  Worse than expected.  The parking garage was about 10°F warmer than outside (32°F per the picture), and the cooling fans were running while charging.

 

The rate per kWh was ridiculous for this area, but I wanted to give it a shot.

 

At home, Dominion VA Power charges:

 

June-September: $0.11049/kWh
October-May: $0.09557/kWh

 

So my Level 2 charger at home costs me $.67 per "fill up" from "0%" to "100%".  I go between 15 and 17 miles per charge due to the hilly terrain even with a 98-99% regenerative braking score, meaning the car costs me $0.044 / mile to operate.

 

YMMV.  Obviously.

 

Edit:  I installed the L2 charger myself, so it cost me the price of the charger ($470), the cost of 50' of 6/3 wire ($150), a 220V 40A breaker ($5), and some conduit ($2).  I've never used the 110V charger.

Edited December 4, 2018 at 02:38 PM by Mr.Fusion