What is the normal percentage of charge to get 300 miles range on ER RWD?

JamieGeek

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There is a bit of marketing involved too. My Chevy Bolt has a 59 kWh battery that it lets me use but I have often argued that the capacity is arbitrarily assigned by the manufacturer. It could be a 65 kWh battery that they rate for 59 kWh.

So Ford could have called the extended range battery 99 kWh with an 11% reserve or they could have called it an 88 kWh battery with no reserve.
Except at some point someone will disassemble the car or reverse engineer the messages on the network and discover the "true" battery capacity.

Thus Ford is being honest: Adding up all the cells you get 99kWh but they will only use 88kWh of it.





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All Hat No Cattle

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Another theory on why Ford set it at a very conservative 11 kW is that they want to be overly sure at first that the batteries are doing fine. And probably collect user data (battery temps and such) for a while, and if it's all looking good, maybe they'll unlock a bit more of that 11 kW buffer with an OTA update. (Perhaps that's more hope than theory.)

Or as you suggest, they may keep it locked and only unlock a smidge at a time as each car ages in order to maintain the 70% range guarantee for 8 years.
Hmmm. If Ford can do an OTA update to access that 11% extra capacity, I wonder how they
keep that capability secure? You know why I ask. :)
 

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There is a bit of marketing involved too. My Chevy Bolt has a 59 kWh battery that it lets me use but I have often argued that the capacity is arbitrarily assigned by the manufacturer. It could be a 65 kWh battery that they rate for 59 kWh.

So Ford could have called the extended range battery 99 kWh with an 11% reserve or they could have called it an 88 kWh battery with no reserve.
"
So Ford could have called the extended range battery 99 kWh with an 11% reserve or they could have called it an 88 kWh battery with no reserve."

Except that the former would have been completely accurate, and the latter completely inaccurate.
 

engnrng

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Hmmm. If Ford can do an OTA update to access that 11% extra capacity, I wonder how they
keep that capability secure? You know why I ask. :)
It is not capacity that is walled off. Charging and discharging rates are based on cell voltages and currents, not kWh. The high capacity forklifts my company builds have a total of 132 kWh theoretical capacity, but the battery manufacturer sets the charge and discharge voltages to yield 100 kWh usable. The battery pack designers do not call the difference a "reserve". It is a design choice. When you design a steel structure, there is an amount of stress that structure can take and remain the same shape, but if you go a little over that stress, you change the shape (the steel yields). Do that too many times and the structure fatigues and breaks. With batteries, it is very similar. As long as you stay within the chosen design envelope, the number of charge cycles you can have and still retain above 80% of original usable capacity is in the thousands. If you charge higher or discharge lower, you reduce that number - a lot. Increase the top end or low end voltage by 0.1V and you could cut that number of charge cycles in half. It is a business decision based on expected lifetime and performance. Use more by going to higher voltages or discharging to lower voltages and the battery will degrade more quickly (electrodes are what change). However, the curve is not linear, it gets much steeper at the top and low ends. Do a search for @EVmodeler in this forum and find the graph he shows for the MME battery system based on his reverse engineered analysis. Ford is choosing to stay in a safer almost linear portion of the zone of voltages, so I expect that my Mach E battery will last longer than I will be able to drive it, 20 years at least, as I am in my 60's. I doubt that Ford will "unlock" anything unless their business goals change to allow for shorter battery lives.

There is another mode of failure with pouch cells (Ford) as opposed to cylindrical cells (Tesla) and that is the seals. Seals have a very long life, but when they start to fail you might as well replace the pack, which Ford has made relatively easy. Pouch cells in general have a better tolerance to temperature extremes and shock/vibration, so are a great choice for vehicle applications. I expect the Ford MME powertrain to be worry free over the first half million miles or so.
 

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Do a search for @EVmodeler in this forum and find the graph he shows for the MME battery system based on his reverse engineered analysis. Ford is choosing to stay in a safer almost linear portion of the zone of voltages, so I expect that my Mach E battery will last longer than I will be able to drive it, 20 years at least, as I am in my 60's. I doubt that Ford will "unlock" anything unless their business goals change to allow for shorter battery lives.
See
https://www.macheforum.com/site/threads/mach-e-extended-range-battery-buffers-and-dcfc-limits.2431/

I too doubt there will much OTA unlocking of battery reserve - its there for good reasons. Just my considered opinion.
 

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But if you're driving somewhere at, say, 65 MPH using climate control in modest weather, and running it from 100% down to 10%, I'd estimate that range to be roughly 220-240. If it's quite cold out, subtract another 10%. If 75 MPH+, subtract another 10%.
Your estimate at 65 MPH is seriously off. Depending on terrain you could easily get OVER 300 miles.

Demonstrating this is straightforward. Just find a flat road and time how long it takes to slow from 70 MPH to 60 MPH. Use that to calculate the power needed in watts (joules per second) to maintain 65 MPH on a flat. That would be P=kg*V*DV/Dt. Kg is given. V = 65 MPH = 29.1 m/s. DV is the change in velocity, so DV = 10MPH = 4.47 m/s. Just plug in the measured time. FWIW this has been done N number of times and yields roughly 15 kW for most vehicles. The rest is just arithmetic: 88X.9=79.2; 79.2/15=5.28; 5.28X65=343.2. So using 90% of a 88 kWh battery pack should yield well over 300 miles of range.

Now someone might not actually get over 300 miles of range. Going up or down even grades as small as 1% matters, and it's also about temperature and technique. However, 300 miles is a far more likely range at 65 MPH than your estimate of 230 miles.
 

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I too doubt there will much OTA unlocking of battery reserve - its there for good reasons. Just my considered opinion.
Agree on technical grounds. But it's also supported by marketing. Given that range is desirable from a consumer prospective, if Ford Marketing thought it could market 325 miles of range rather than 300 miles of range it would be hard not to make it so.
 

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Except at some point someone will disassemble the car or reverse engineer the messages on the network and discover the "true" battery capacity.

Thus Ford is being honest: Adding up all the cells you get 99kWh but they will only use 88kWh of it.
The EPA CSI also quotes the capacity as 288 Ah, so it is known. The energy capacity comes from the nominal pack voltage, usually from a modest C/3 (capacity discharge rate, in this case 288/3 = 96 Amp) or also about 50% SoC.
That nominal voltage is somewhat variable in the EPA CSI data, and some manufacturers give the max voltage, not the nominal voltage to get the correct energy capacity. The nominal open circuit voltage of the ER pack is about 342 V; 342 V * 288 Ah (/1000) = 98.5 kWh.
The energy you get at the terminals depends how fast you push it in or out (current vs voltage drop from battery internal resistance) but you can never put in or take out more than 288 Ah (without severely damaging the battery).
 

dbsb3233

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Your estimate at 65 MPH is seriously off. Depending on terrain you could easily get OVER 300 miles.

Demonstrating this is straightforward. Just find a flat road and time how long it takes to slow from 70 MPH to 60 MPH. Use that to calculate the power needed in watts (joules per second) to maintain 65 MPH on a flat. That would be P=kg*V*DV/Dt. Kg is given. V = 65 MPH = 29.1 m/s. DV is the change in velocity, so DV = 10MPH = 4.47 m/s. Just plug in the measured time. FWIW this has been done N number of times and yields roughly 15 kW for most vehicles. The rest is just arithmetic: 88X.9=79.2; 79.2/15=5.28; 5.28X65=343.2. So using 90% of a 88 kWh battery pack should yield well over 300 miles of range.

Now someone might not actually get over 300 miles of range. Going up or down even grades as small as 1% matters, and it's also about temperature and technique. However, 300 miles is a far more likely range at 65 MPH than your estimate of 230 miles.
So you're saying that Ford's numbers are way off then.

Ford says 300 miles on the EPA test, which is mostly low-medium speeds. And that's 0-100% SOC. Adjust that to the 10-100% real-world scenario I used and it's 270. Nearly every BEV experiences worse efficiency at higher speeds. They also lose efficiency for use of climate control, which I also stipulated for the scenario. And "modest weather". That's why I adjusted the 270 down to 220-240.

Adjusting for climate control use and high speed, you must think EPA range should be what, something around 360? That seems like it would have to be the rough starting point when subtracting for 10% stopping point, high speed loss, climate control use, and modest weather, in order for you to arrive at 300 miles for the scenario I referred to.

I hope you're proven right. Way better range than Ford is advertising would be great.
 

GoGoGadgetMachE

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What OS does Ford use for it's embedded systems?
I assume QNX as that is what underpins Sync 3 and there's no reason to change it.
 

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Ford says 300 miles on the EPA test, which is mostly low-medium speeds.
Don't forget the Highway label consumption (and so range) is adjusted down to better reflect actual highway speeds. And similar for city and combined.

See here for a breakdown of city and highway range based on label values;
the actual label only gives combined range.
https://www.macheforum.com/site/thr...nge-estimates-from-window-sticker-label.2268/

And of course the label values are based on the usable battery capacity. The test stops when the vehicle can no longer hold speed, so when the vehicle says Enough! (vehicle/BMS controller reaches discharge limit)
 

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Don't forget the Highway label consumption (and so range) is adjusted down to better reflect actual highway speeds. And similar for city and combined.

See here for a breakdown of city and highway range based on label values;
the actual label only gives combined range.
https://www.macheforum.com/site/thr...nge-estimates-from-window-sticker-label.2268/
Yep. It's showing 8% less for "highway" (276) vs the main "combined" number (300). So that's 8% off for highway and 10% off for leaving 10% "in the tank" for the next refuel. 18% off 300 is 246.

Then factor in climate control, which can easily use up around 10% in modest weather. That takes it up to 28% off (216).

My initial 220-240 estimate may have actually been a bit generous.
 

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