MME M/KWh Efficiency and M/kWh Calculation Accuracy

Colorider

Well-Known Member
First Name
Kristian
Joined
Nov 24, 2020
Threads
17
Messages
96
Reaction score
200
Location
Colorado Springs
Vehicles
Standard AWD
Country flag
Now that I have 1k+ miles on my Select AWD wanted to start playing around with the numbers ?. For the first Trip 2, I drove 1,055 miles* and the computer said a pretty impressive 4.1 Mi/KWh! However when I look at my ChargePoint I used 294KWh so that is really 3.6 Mi/KWh I’m still very happy about that but it’s 12.5% worse that the car’s calculation.

Today I reset Trip 1 and tried to see what a fairly normal day looked like. I drove 37.5 miles and just barely got the guesser up to 4.8Mi/KWh as I pulled into the garage. “Pumping” it back up to the 70% charge that I left with took 9.53KWh so the real math is 3.9Mi/KWh which is a -18% difference from the computer! Again, I’m STOKED to get 3.9 so don’t get me wrong here, I just wish the computer were a little closer to reality.

I will continue to test things with different driving styles/modes and in different weather and post them up on this thread. Please feel free to do the same.

Ford, if you’re listening, please put out some better analytics with instant M/KWh and deceleration KWh recapture rates on an OTA ?. Oh, and this car rocks—thank you for building it!
Ford Mustang Mach-E MME M/KWh Efficiency and M/kWh Calculation Accuracy C2BC1A5F-8221-463E-8E51-36685801A712
Sponsored

 
Last edited:

Ciero

Well-Known Member
First Name
K
Joined
Aug 28, 2020
Threads
3
Messages
183
Reaction score
252
Location
Michigan
Vehicles
Mach E 4x Premium Edition, Explorer Sport
Country flag
When you're charging there is loss, so you're going to put more energy in than you take out. This is especially true the closer you get to max charge. I'm guessing both your car and your charger are pretty accurate, but they're telling different stories.
 

JoeDimwit

Well-Known Member
First Name
Joe
Joined
Mar 1, 2021
Threads
67
Messages
1,712
Reaction score
3,239
Location
Waterford
Vehicles
Grabber Blue First Edition
Occupation
Electrician
Country flag
I
When you're charging there is loss, so you're going to put more energy in than you take out. This is especially true the closer you get to max charge. I'm guessing both your car and your charger are pretty accurate, but they're telling different stories.
f you have accurate mileage, and accurate power in readings, then it’s pretty straightforward math to figure out the M/kWh. If that M/kWh is off from what the car is saying, by >10%, then whatever story the car is telling is wrong.
 

SpacePony

Well-Known Member
Joined
Mar 29, 2021
Threads
5
Messages
206
Reaction score
363
Location
Kansas City Metro
Vehicles
2021 Mach-e Preimum AWD Ext. Battery
Country flag
As @Ciero said, your ChargePoint is reporting how many kWhr it output for those charges. But there is charger loss and overhead (to run things like the cooling system while charging) that can amount to between 5-20% loss depending on conditions and the voltage/wattage (generally you want to shoot for the highest voltage and lowest amperage possible). So if you’ve got a 220v EVSE, a 50 amp charger will incur more loss than a 20 amp. But 110v is the worst of all.

The car might be off a little bit. But
the figures you’re giving actually do more to confirm that the car is pretty close to correct than they do to suggest it’s wrong.
 
OP
OP
Colorider

Colorider

Well-Known Member
First Name
Kristian
Joined
Nov 24, 2020
Threads
17
Messages
96
Reaction score
200
Location
Colorado Springs
Vehicles
Standard AWD
Country flag
That makes sense—you hear a powerful fan when you plug in and that is definitely going to take some juice. Still, I think looking at just the electrons burned while driving isn’t the right standard for efficiency. If I put 10G of gas in my ICE car, that is the denominator because it is about the energy used. The only time to ignore that is when seeing how far you can drive on a charge but JoeDimwit recently cast some doubt on those numbers in a different thread.
 


Shayne

Well-Known Member
Joined
Aug 9, 2020
Threads
18
Messages
3,340
Reaction score
2,487
Location
Northern Ontario Canada
Vehicles
2021 MME4x Prem
Occupation
Retired
Country flag
When you're charging there is loss, so you're going to put more energy in than you take out. This is especially true the closer you get to max charge. I'm guessing both your car and your charger are pretty accurate, but they're telling different stories.
Using the EPA results. Recharge Event Energy (kiloWatt-hours) 101.2 . 13% loss 87% efficient.
That makes sense—you hear a powerful fan when you plug in and that is definitely going to take some juice. Still, I think looking at just the electrons burned while driving isn’t the right standard for efficiency. If I put 10G of gas in my ICE car, that is the denominator because it is about the energy used. The only time to ignore that is when seeing how far you can drive on a charge but JoeDimwit recently cast some doubt on those numbers in a different thread.
That is why EPA uses the 101.2 KWh to state efficiency but what was stating in the OP was that the consumption ford states is way off. These are two different things and should be off by at least 10%.
 

timbop

Well-Known Member
First Name
Tim
Joined
Jan 3, 2020
Threads
63
Messages
6,729
Reaction score
13,758
Location
New Jersey
Vehicles
Solar powered 2021 MME ER RWD & 2022 Corsair PHEV
Occupation
Software Engineer
Country flag
When you're charging there is loss, so you're going to put more energy in than you take out. This is especially true the closer you get to max charge. I'm guessing both your car and your charger are pretty accurate, but they're telling different stories.
As @Ciero said, your ChargePoint is reporting how many kWhr it output for those charges. But there is charger loss and overhead (to run things like the cooling system while charging) that can amount to between 5-20% loss depending on conditions and the voltage/wattage (generally you want to shoot for the highest voltage and lowest amperage possible). So if you’ve got a 220v EVSE, a 50 amp charger will incur more loss than a 20 amp. But 110v is the worst of all.

The car might be off a little bit. But
the figures you’re giving actually do more to confirm that the car is pretty close to correct than they do to suggest it’s wrong.
Exactly. The EVSE is showing you how much was taken from the grid, and the car is reporting what went from the battery to the wheels. In between those 2 metrics is loss due to heat when charging. I have a 32A charger which draws 7.7 kw from the grid, but from watching the per hour charge percentage only about 6.6 kw is going into the battery - for a roughly 15% loss. That's also why the EPA MPGe numbers don't exactly correlate with the EPA range numbers; the MPGe numbers take into account the heat loss and thermal management while charging because they are measured from the grid.
 

mixduptransistor

Well-Known Member
First Name
joe
Joined
Feb 28, 2021
Threads
12
Messages
455
Reaction score
492
Location
Atlanta
Vehicles
2021 Rapid Red Mach E Premium Extended Range RWD
Occupation
Systems Engineer
Country flag
If I put 10G of gas in my ICE car, that is the denominator because it is about the energy used.
The difference is that all 10 gallons made it to the car. The gas station doesn't use any of your gasoline to operate the gas pump. Part of the electricity your ChargePoint is sending to the car is not going into the battery, it's running the charging infrastructure in the car. That little bit of power lost is the explanation for the difference between what's reported at the power meter and what's reported in the car
 

Timelessblur

Well-Known Member
First Name
Tyler
Joined
Oct 6, 2020
Threads
1
Messages
392
Reaction score
448
Location
Austin
Vehicles
Mach E AWD Premium Extend Range RR
Occupation
Software Developer
Country flag
12.5% charging loss is better than I was expecting and hoping for honest. I have been assuming a 15% loss on charging.
 

BMT1071

Well-Known Member
First Name
Mike
Joined
Mar 21, 2021
Threads
61
Messages
3,073
Reaction score
4,223
Location
Glendale, AZ
Vehicles
21 MME SR RWD, 23 MME GTPE
Occupation
Regional Service Manager
Country flag
I believe the kWh number that FordPass reports is what actually made it to the battery. Can one of you lucky individuals that actually has an MME confirm? If so, that's the number you need to use to check the car's math, not the CPHF number.
 

theo1000

Well-Known Member
First Name
Theo
Joined
Apr 16, 2021
Threads
0
Messages
473
Reaction score
607
Location
Shawnee, KS
Vehicles
Mach-E 2021 IB, Audi Etron, Chevy Volt, BMW I3,
Country flag
I think we have to start a campaign for Ford to add SoC info to the display. The car knows all this info. When the BMW I3 first came out there was no SoC display and the owners collectively forced BMW to add it on a software update. Not sure why we have to fight this battle again but here we are.
 
OP
OP
Colorider

Colorider

Well-Known Member
First Name
Kristian
Joined
Nov 24, 2020
Threads
17
Messages
96
Reaction score
200
Location
Colorado Springs
Vehicles
Standard AWD
Country flag
I believe the kWh number that FordPass reports is what actually made it to the battery. Can one of you lucky individuals that actually has an MME confirm? If so, that's the number you need to use to check the car's math, not the CPHF number.
It only gives a %, not the actual KWh.
 

ARK

Well-Known Member
Joined
Aug 21, 2020
Threads
42
Messages
2,732
Reaction score
3,986
Location
Los Angeles
Vehicles
Mustang Mach E
Country flag
I agree that something seems off about the trip computer. My Trip 1 and 2 have never been reset since I took delivery. I have driven about 1554 miles and my Mach-E says total trip time is about 20 hours and 12 minutes.

If I am understanding this correctly, that comes out to an average of approximately 77 mph, an unrealistic number for me because the vast majority of my driving is local and I do not often take the freeway.
 

timbop

Well-Known Member
First Name
Tim
Joined
Jan 3, 2020
Threads
63
Messages
6,729
Reaction score
13,758
Location
New Jersey
Vehicles
Solar powered 2021 MME ER RWD & 2022 Corsair PHEV
Occupation
Software Engineer
Country flag
I believe the kWh number that FordPass reports is what actually made it to the battery. Can one of you lucky individuals that actually has an MME confirm? If so, that's the number you need to use to check the car's math, not the CPHF number.
It only gives a %, not the actual KWh.
Yes, during charging if you look into the charging details there is a field that displays the kwh that has made it into the car. After the last fordpass update when I looked at that value it said "not available". Naturally the charging log doesn't have this field either.

Regardless, when it was displaying it was a whole number so in my case would report 13kwh after 2 hours of charging, which roughly matched the 15% gained (extended range battery). This is a 32A charger which is drawing 7.7 kw
 
Last edited:

Murse-In-Airy

Well-Known Member
First Name
Rod
Joined
Mar 5, 2021
Threads
74
Messages
3,389
Reaction score
7,618
Location
Chaumont, NY
Vehicles
Mach-E ER AWD
Occupation
Nurse
Country flag
It only gives a %, not the actual KWh.
The FordPass charge log only shows percent. But if you check the app while the car is still plugged in, open the current charge session, and scroll down, it does indeed show kWh added.
Sponsored

 
 




Top