Easiest way to compute mileage?

[RickEnergi]

I'm interested in being able to easily(?) compute my cost of fuel in driving our Energi.

 

We charge with the regular wall charger, so we are unable to track kWh of energy being used to charge the vehicle.  I know of the loss of electricity from the wall to the vehicle.

 

I reset Trip 2 when we bought the vehicle, so it has cumulative information stored.  I also know how many gallons of gas I've put in.  And I know what I pay for electricity, and have been saving my driving record each week in a PDF, once I realized it disappears from MyFordMobile after a week or so (depending on number of trips and charges).

 

How do people that track fuel usage do this?  

 

I find the Trip info confusing, because I think it's including energy generated by braking and coasting, no?  So for my last tank, I went 733.4 miles on 10.75 gallons of gas, and I used 150 kWh.  If that didn't include braking and coasting, I could simply take that number, use say 72% efficiency, use my cost of electricity, and then do a cost per mile including gas.  

 

Any insights, pointing towards references that give some better explanations and ways to track things?  I want to track gas used, electricity (from wall) used, then compute cost per mile driven.

 

I have an OBDII reader (I use FORScan on my F-150) if info is stored somewhere that I can go find periodically.

Edited December 22, 2018 at 05:33 PM by RickEnergi

[murphy]

The easiest way is to buy an EKM meter and measure the energy that the car uses.

 

https://www.ekmmetering.com/collections/electric-meters-kwh-meters/products/120-volt-pass-through-kwh-meter-2-wire-1-hot-1-neutral-50a-60hz-ekm-15ids

 

is the 120 volt version.  The 240 volt version is 25IDS.

[RickEnergi]

I used a Kill-O-Watt to measure the juice coming out of the wall for a week (library loan).  I'm trying to find out if there is anything saved in the car somewhere that tells me "you got XXX kWh" while plugged in that I can record at each gas fill up.  It seems to me that all the readings in the car including electricity generated by regenerative braking and coming off the gas pedal.  That's free, I want to track the electricity I paid for.  

[murphy]

The only way to do that is to measure what comes from the wall.  The car doesn't know what came from the wall.  My recollection is that 120 volt charging is about 70% efficient.  240 volt charging is around 80% efficient.  Unlike a Kill-A-watt, the meter I referenced can't be reset and will retain its reading, in the absence of input power, for 10 years.