EV, HV, MPGe calculations...

Go to ur menus, tap information, past records, tape the data you want to view. Update it every tank of gasoline change or between ev or hv model. It will do all the math for you. And if you scheduled ur charging time. Found the amount of money you spent on those hrs and do a simple math. You will ur mile/g/price. And kwm/charge/price

 

We have now owned our 2018 Prime plus for about three weeks. Just finished the first tank at about 1500 kms traveled. I'd like to determine how many EV kms we have traveled. The odometer tells me total kms traveled, but I don't see a breakdown that would tell me # Kms of Electric only travel, other than the daily/monthly log.

 

My full charges have been closer to 6.8 - 7.2 kWh.

My full charges on the charger have been from 6.8 - 7.2 kWh. I used a Kill A Watt meter.

 

My full charges have been between 6.2 and 6.5kWh.

 

The ambient temperature may be causing the differences?

 

Doubt it. 6.3kWh all year, on two different meters using two different chargers. It's a little more if you manage to consume some of the portion of the charge preserved for hybrid mode.

Prime full charge | PriusChat

 

The easiest way to record data from the Prius Prime is to photograph the Distance/Average MPG and the miles/km/AC Load Ratio displays on the dashboard. I also include TRIP miles (which I do not reset) and Avg MPG in the pictures, which I take with my cellphone.

Note that the "Distance" number does not round correctly (it often under-reports by 0.1 miles), so it it more accurate to get the distance from the difference in successive trip odometer readings, which are rounded correctly.

Additional data can be captured from the Entune "ECO Dashboard" cellphone app. In particular, the app reads daily and monthly fuel economy up to 999.9 MPG, which allows better estimation of gasoline use. I enter all of this data and more into a spreadsheet, in which I calculate the kWh and gasoline used for each trip. I also compare these with Kill-A-Watt meter kWh readings and fuel receipts. The kWh from the meter is generally 10% to 20% higher than that computed from miles/kWh, because some energy is lost in the charging process. The gasoline usage estimates from MPG are about 10% low, probably because of errors in estimating the usage from the fuel injector timing; thus the MPG readings are probably about 10% too high.

Given this information, it is possible to get some idea how much of the energy consumed comes from gasoline and how much from the electric grid. For example, overall gasoline economy for the entire life of the car has been 138.6 MPG, while highway driving in hybrid mode has been about 62 MPG. This tells me that at least half the miles driven have been powered by the electric grid.

 

I live in Canada and so I have always compared vehicles based on miles per Imperial gallon. So of course, in order to brag, I have come up with an equation that will give that to me. To explain how I did it and allow someone out there to correct it if I am under wrong assumptions...
1. I list the total km travelled (the odometer) on my spreadsheet. I then list the KW per 100 kilometres in the second column. That is found on the dash readout above where it lists the km I have left on ev mode. The third column is the total kilowatts consumed since the vehicle was new ( I bought mine new). In the third colum I take the first column and divide it by 100 and multiply by the second column. In the fourth column I indicated the price I pay for electricity at home where I charge it every day. The fifth column takes the kw used and multiplies it by the cost per kw that I pay. (Column three times column four) In column six I list the literas per 100 km that shows on the same screen as the odometer reading (just to the right). In column seven I track the amount of gas used in litres. (Litres/100km). The equation is as follows ( col 6×(Col 1×0.001)). The next column lists the amount I pay for a liter of gas. If you keep track of your gas costs separately you can just plug in the average cost here. The ninth column will be be column 7 times the column 8 which will give you the total cost of gas used in the life of your vehicle... column 10 is the total cost of driving (column 5 plus column 9). Column 11 which (divides column 10 by column 1) then multiplies by 100. Column 12 is the litres per 100 km (column 11 divided by 1.35). Column 12 is the one that I wanted from the start (miles per Gallon). I found a formula on line (not sure exactly how accurate) that shows if you take the litres per 100 km (column 12) and multiply by 106.2363 you get the miles per Canadian gallon.
I have so far driven 510 kilometres and have registered 166.295 miles per gallon equivilent...

If there are any math experts out there can see where I have made an error..? So far I have used (according to the car) 74.1 kw of electricity at an average price of 13.9 cents per kilowatt. As well I have used .2 litres of gas at 1.40 per liter. My total costs for 501 Kim has been $10.59 Canadian...

 

First of all, welcome to the Prius Chat.

I am not a math expert and reading your formulation in words rather than numbers makes it even more difficult to understand how you are getting the final numbers. Added to that, metric unit and imperial gallon are different from my usual number system to confuse me more. Will you show us an actual spreadsheet you have kept your record and formula used to get each number?

The most difficult part of calculating the actual mpg for HV and mpge for EV on PRIME is to know the distance traveled under each mode. The car, unfortunately, does not give us those numbers in any place, and recording them manually is a daunting task AFAIK.

 

I have attached the spreadsheet I used. Please not that it will be mor accurate after driving for a greater distance. You will notice that my friend John has over 3000 kilometres since April and has never put in gas to date...

 

It's getting late, and I can't think clearly. One question I have is where the number "1.35" came from in calculating column 12?

I think the final number in column 13 is including both gallon equivalent of the electricity used and actually used gasoline, but not sure if that is very useful representation unless you are using pure gas. I have heard the gallon equivalent electricity 33.6kWh is for pure gas, not for ethanol-blended gas. Also using kWh/100km displayed on the car will not give you the real cost of electricity you are actually paying. The number on DM2 is most likely based on the actual energy used by the motor from the traction battery, however, what you are paying to charge the traction battery will be higher than that. It will have energy loss during charging and delivery to the motor as well as any use of traction battery for the non-traction purpose such as AC, lights, radio, etc.

 

You may very well be right regarding electricity usage for traction. Maybe someone who knows how the car measures kw/100 km can clarify...

 

I just noticed your question about where I got the 1.35 from (column 12). When I initially set it up I was using the price that I have to pay for a liter of gas in the equation. Later I put $1.40 in column 9 so now I have used col 9 in place of the 1.35 in the calculations...