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Discussion Starter · #1 ·
I finally gave in to my urge to calculate my own performance numbers for my Premium MME with ER battery. I was tired of the error in the GOM (Guess-O-Meter) along with errors in driving distance, and M/kwh. It is also very difficult to tell how much juice you are putting into the car, at what price, to determine cost/mile. There is no instrumented way in the MME to view the different performance numbers while driving at different speeds. I experienced vast differences between city and highway driving numbers.

I start by recording some info from the dash and the trip meter which I reset (Trip 2) each time I charge.

So I embarked on collecting my own info. First thing I had to do was get a charger that told me how much juice (kwh) I was putting in, and the cost. ChargePoint to the rescue. It gives me both. Below is a screenshot of a recent charge.



I have the Ford charger at my home, and it has a different rate and cost. My calculations use whatever is appropriate.
I also use the FordPass app to read off more final charging numbers.

Then I built a spreadsheet with the following inputs. Some are input when I start charging (yellow) and some when it is complete (orange). I will say that my calculations do assume that the battery charge level % is accurate. I have no way of determining the battery charge % other than what Ford tells me, so I have to use that.


Once the charge is complete, and the data is filled in, a results bar for each charge calculates results as below:




It tells me all the above data for each charge, and then calculates median or average figures (shown above right above the blue bar). The outputs/results are in order:
How many hours the charger was on
How many Kwh the charger transferred (based on measurement at the plug)
How many MPH the charger was charging
How many miles it added, using the Historic m/Kwh from the MME
What the calculated total usable miles are now on the car, using the % Charge, battery size, and Hist m/Kwh
What the average speed was since the last charge. Total miles / hours driving.
What the $/mi are
What the GOM difference shows between last charge and this one
What the actual difference is given the miles driven
What the error is in the GOM. This has varied between under by 24% to over by 30%. Mean is shown. i.e. the Ford GOM estimates 12% high.
What the actual m/Kwh are. My MME Trip meter shows consistently 3.7 m/Kwh while actually it is 3.3 m/Kwh. This is consistent with Ford GOM error at about 12% high, so they could be based on the erroneous GOM.
Efficiency of the charge circuit based on comparing the input from the wall to the actual battery charge.

Note that the GOM error is one that is incurred from a low charge to a higher charge. i.e. the GOM at a higher charge (for example at the beginning of a trip), compared to the GOM at a lower charge (at the end of a trip) is high. This gives you a false sense of security in that it is telling you that you can go 12% farther than you actually can, but doing so in a slow, unnoticeable incremental way. This could be an error in the battery % charge level, but there is no way of knowing that.

This is a limited data set at this point. While I have been keeping a record for some time, I did not collect all the right data all along, so the above represent only about 450 miles and 5 charges in warm fall weather. However, the averages are starting to settle so I don't expect them to change much.

I don't know what to expect with winter charging and driving temperatures and how to calculate the effect.

I wish there was some more instrumentation on the MME.

Comments or suggestions welcome in my ongoing siege.

Jim
Premium, Infinite Blue Metallic, Black Onyx interior, RWD, ER Battery, no front license bracket.
 

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Lots of work went into this, thanks! Keep us updated please. BTW, I love your tag line, ‘no front license bracket’. I never attached mine on my ‘18 ecoboost performance pack(that I traded in for the MME). The dealer installed the front bracket on my MME Premium eAWD before I could say anything, so I just went with it.
 

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2021 Premium AWD 2021 Select AWD (sold)
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Thanks for the post! Lots of people have indicated that their GOM is overly conservative but I’ve had the opposite experience. My data is in line with yours - that real-world milage is at least 10% lower than the GOM. Probably no where near as bad as Tesla, at least.
 

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Discussion Starter · #4 ·
I just did a battery charge test.
I charged the MME from 52% to 90%: 38% charge added
I have a 88Kwh ER battery. 38% of 88 Kwh = 33.4 Kwh that the battery measured it took on
I measured the Kwh that the charger put into the car. It was 36.7 Kwh.
I have previously measured the MME charger efficiency at 96%, so really only 35.2 Kwh were imparted.
That is an MME error of about 5%.
i.e. the battery charging and display algorithm is about 5% low from mid to full charge,
or in other words the battery is showing a 5% lower charge than is really there.

This is at odds with the GOM error algorithm. The battery goes one way, the GOM the other.
Confusing.
 

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I finally gave in to my urge to calculate my own performance numbers for my Premium MME with ER battery. I was tired of the error in the GOM (Guess-O-Meter) along with errors in driving distance, and M/kwh. It is also very difficult to tell how much juice you are putting into the car, at what price, to determine cost/mile. There is no instrumented way in the MME to view the different performance numbers while driving at different speeds. I experienced vast differences between city and highway driving numbers.

I start by recording some info from the dash and the trip meter which I reset (Trip 2) each time I charge.

So I embarked on collecting my own info. First thing I had to do was get a charger that told me how much juice (kwh) I was putting in, and the cost. ChargePoint to the rescue. It gives me both. Below is a screenshot of a recent charge.

View attachment 7161

I have the Ford charger at my home, and it has a different rate and cost. My calculations use whatever is appropriate.
I also use the FordPass app to read off more final charging numbers.

Then I built a spreadsheet with the following inputs. Some are input when I start charging (yellow) and some when it is complete (orange). I will say that my calculations do assume that the battery charge level % is accurate. I have no way of determining the battery charge % other than what Ford tells me, so I have to use that.

View attachment 7162
Once the charge is complete, and the data is filled in, a results bar for each charge calculates results as below:

View attachment 7164


It tells me all the above data for each charge, and then calculates median or average figures (shown above right above the blue bar). The outputs/results are in order:
How many hours the charger was on
How many Kwh the charger transferred (based on measurement at the plug)
How many MPH the charger was charging
How many miles it added, using the Historic m/Kwh from the MME
What the calculated total usable miles are now on the car, using the % Charge, battery size, and Hist m/Kwh
What the average speed was since the last charge. Total miles / hours driving.
What the $/mi are
What the GOM difference shows between last charge and this one
What the actual difference is given the miles driven
What the error is in the GOM. This has varied between under by 24% to over by 30%. Mean is shown. i.e. the Ford GOM estimates 12% high.
What the actual m/Kwh are. My MME Trip meter shows consistently 3.7 m/Kwh while actually it is 3.3 m/Kwh. This is consistent with Ford GOM error at about 12% high, so they could be based on the erroneous GOM.
Efficiency of the charge circuit based on comparing the input from the wall to the actual battery charge.

Note that the GOM error is one that is incurred from a low charge to a higher charge. i.e. the GOM at a higher charge (for example at the beginning of a trip), compared to the GOM at a lower charge (at the end of a trip) is high. This gives you a false sense of security in that it is telling you that you can go 12% farther than you actually can, but doing so in a slow, unnoticeable incremental way. This could be an error in the battery % charge level, but there is no way of knowing that.

This is a limited data set at this point. While I have been keeping a record for some time, I did not collect all the right data all along, so the above represent only about 450 miles and 5 charges in warm fall weather. However, the averages are starting to settle so I don't expect them to change much.

I don't know what to expect with winter charging and driving temperatures and how to calculate the effect.

I wish there was some more instrumentation on the MME.

Comments or suggestions welcome in my ongoing siege.

Jim
Premium, Infinite Blue Metallic, Black Onyx interior, RWD, ER Battery, no front license bracket.
In the very basic sense, do you think the miles/Kwh indication on the trip meter is accurate?
 

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I finally gave in to my urge to calculate my own performance numbers for my Premium MME with ER battery. I was tired of the error in the GOM (Guess-O-Meter) along with errors in driving distance, and M/kwh. It is also very difficult to tell how much juice you are putting into the car, at what price, to determine cost/mile. There is no instrumented way in the MME to view the different performance numbers while driving at different speeds. I experienced vast differences between city and highway driving numbers.

I start by recording some info from the dash and the trip meter which I reset (Trip 2) each time I charge.

So I embarked on collecting my own info. First thing I had to do was get a charger that told me how much juice (kwh) I was putting in, and the cost. ChargePoint to the rescue. It gives me both. Below is a screenshot of a recent charge.

View attachment 7161

I have the Ford charger at my home, and it has a different rate and cost. My calculations use whatever is appropriate.
I also use the FordPass app to read off more final charging numbers.

Then I built a spreadsheet with the following inputs. Some are input when I start charging (yellow) and some when it is complete (orange). I will say that my calculations do assume that the battery charge level % is accurate. I have no way of determining the battery charge % other than what Ford tells me, so I have to use that.

View attachment 7162
Once the charge is complete, and the data is filled in, a results bar for each charge calculates results as below:

View attachment 7164


It tells me all the above data for each charge, and then calculates median or average figures (shown above right above the blue bar). The outputs/results are in order:
How many hours the charger was on
How many Kwh the charger transferred (based on measurement at the plug)
How many MPH the charger was charging
How many miles it added, using the Historic m/Kwh from the MME
What the calculated total usable miles are now on the car, using the % Charge, battery size, and Hist m/Kwh
What the average speed was since the last charge. Total miles / hours driving.
What the $/mi are
What the GOM difference shows between last charge and this one
What the actual difference is given the miles driven
What the error is in the GOM. This has varied between under by 24% to over by 30%. Mean is shown. i.e. the Ford GOM estimates 12% high.
What the actual m/Kwh are. My MME Trip meter shows consistently 3.7 m/Kwh while actually it is 3.3 m/Kwh. This is consistent with Ford GOM error at about 12% high, so they could be based on the erroneous GOM.
Efficiency of the charge circuit based on comparing the input from the wall to the actual battery charge.

Note that the GOM error is one that is incurred from a low charge to a higher charge. i.e. the GOM at a higher charge (for example at the beginning of a trip), compared to the GOM at a lower charge (at the end of a trip) is high. This gives you a false sense of security in that it is telling you that you can go 12% farther than you actually can, but doing so in a slow, unnoticeable incremental way. This could be an error in the battery % charge level, but there is no way of knowing that.

This is a limited data set at this point. While I have been keeping a record for some time, I did not collect all the right data all along, so the above represent only about 450 miles and 5 charges in warm fall weather. However, the averages are starting to settle so I don't expect them to change much.

I don't know what to expect with winter charging and driving temperatures and how to calculate the effect.

I wish there was some more instrumentation on the MME.

Comments or suggestions welcome in my ongoing siege.

Jim
Premium, Infinite Blue Metallic, Black Onyx interior, RWD, ER Battery, no front license bracket.
Wow! great work. I'm wondering I may have missed it in the writeup. When you calculated your cost per kwh did you factor in taxes that you pay. For instance, here in GA, our flat rate is 5.7 cents kwh. but factoring in the taxes puts it at about 13 cents per kwh. I arrived at this by taking an average months electric bill and dividing the total of the bill by the kwh used. to get that figure. It's not perfect but feel it gives a more accurate picture. I have a friend with a tesla, also in ga, he goes for the special off hours charging rate of around 2 cents per kwh, but to me this doesn't give an accurate indication of true monthly charging costs.
 

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Discussion Starter · #7 ·
My $/Kwh was calculated using all of generation & transmission ($0.074), distribution ($0.023) and a small "other" fee. No taxes on residential electricity accounts in TX.

Jim
 

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Discussion Starter · #8 ·
In the very basic sense, do you think the miles/Kwh indication on the trip meter is accurate?
No it is not accurate. Over the past 767 miles, it has averaged 3% high. However, if I look at the variation in what the GOM shows and my actual mileage driven in each recharge case, the variation is huge. From the GOM reading 24% low, to 30% high.

In other words, at any given time, the GOM shown could be + or - 25 to 30 % wrong.

So no it is not accurate and the average error is useless number given the large standard deviation.
 
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