Mach E web series Part 4 - Performance and Charging

[silverelan]

True but simulated screens are far from an intentional tease. Darren's interview last week explicitly saying well over 300 miles is quite different. I'm hopeful but won't bet on it.

I am pretty skeptical but the hints keep coming and they're harder to ignore as we get closer to delivery.

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[dbsb3233]

This was in the answers I posted:

"Will charging the Mach-E have a taper toward the end of charging and at what SOC will the taper take place? The charge will begin to taper at 80% SOC."

Now . . . if that is true and correct, that is pretty significant. If it can hold the 150KW all the way up to 80%, it seems to me that is pretty good, and you will primarily charge during road trips at DCFC between 10 and 80%. Some cars begin to taper their speeds much sooner.

If that's even remotely close to being accurate, then their original (and still existing) charging times are blown to hell. Which I really doubt.

Holding 150 kW from 10% all the way to 80% would mean 70% of 88 kWh = 61.6 / 150 = 0.41 hours (25 minutes). Ford continues to state 45 minutes.

While that would be fantastic, I just don't see it. Ford would be shouting it from the rooftops. Or at least strongly hinting at dramatic improvement coming.

 

[dbsb3233]

@dbsb3233 , have you had your mind changed yet on the 61 miles/10 minutes (52 for AWD) being the average over the charging session and not just the first ten minutes?

Not until I see Ford announce a reduction in that 45 minutes for 10-80% SOC. That's the key number that projects what it is beyond the first 10 minutes. And they repeat that 45 minute number both in original info and in the revised info. So as much as I'd love for it to improve dramatically, I just can find another way for it to fit without a fairly fast taper (like around the 30-35% SOC mark).

If there were dramatic improvement coming, I think we'd at least be getting hints (even if they're holding the official numbers for EPA announcement). I could see modest improvement coming, but holding 150 to 80% would be a massive surprise to me.

 

[KAustin]

Is there a probably holding the charge for a longer period at 150? I guess it has been stated that "super charging" will degrade the battery quicker. The key when more EVs get on the road is how quickly they can charge when traveling.

 

[dbsb3233]

Is there a probably holding the charge for a longer period at 150? I guess it has been stated that "super charging" will degrade the battery quicker. The key when more EVs get on the road is how quickly they can charge when traveling.

The problem is heat. Charging a rechargeable battery produces heat, and too much heat damages the battery. Slower "trickle" charging causes little heat. But crank the power up to charge faster and the heat increases.

From what I understand, it also increases the fuller the battery gets. Has to do with the way batteries work. In a simplistic sense, the more electrons they fill up with, the less "space" to jam more in, and the more heat created (that's a crude description but it gives you the idea). That's why the power level is tapered down the fuller the battery gets.

 

[ChasingCoral]

Is there a probably holding the charge for a longer period at 150? I guess it has been stated that "super charging" will degrade the battery quicker. The key when more EVs get on the road is how quickly they can charge when traveling.

The longer you charge at maximum the hotter the battery gets. Darren mentioned that last night. You can help this with good battery temperature management but there are physical limits on this. If Ford keeps the rate near 150 kW for a large portion of the charging curve, it will be largely due to improved battery management (hardware and software).

This is a potential issue with Tesla moving to a physically larger battery cell. The tendency to heat up rises with higher volume cells. The ability to cool them rises with higher surface area. You can counter this with increasing the material that serves as heat syncs to allow heat to move from the inside of the cell to the outside but that adds weight and bulk. This is the reason animals in the tropics tend to be smaller than animals at high latitudes. Canadian deer are huge. Florida deer are tiny. Elephants combat the heat with large heat syncs (their ears) and special behaviors.

 

[silverelan]

Not until I see Ford announce a reduction in that 45 minutes for 10-80% SOC. That's the key number that projects what it is beyond the first 10 minutes. And they repeat that 45 minute number both in original info and in the revised info. So as much as I'd love for it to improve dramatically, I just can find another way for it to fit without a fairly fast taper (like around the 30-35% SOC mark).

If there were dramatic improvement coming, I think we'd at least be getting hints (even if they're holding the official numbers for EPA announcement). I could see modest improvement coming, but holding 150 to 80% would be a massive surprise to me.

Average range gained will be 61-52 miles / 10 minutes over a period of ~40 minutes. This works if the range is like 350 miles for RWD and near 320 miles for AWD.

I don't see how the MME can hold 150kW like the e-tron to 80%. That doesn't make sense to me.

 

[ajmartineau]

I don't want my car charging at 150kW to 80%. That would be very hard on the battery.

 

[GoGoGadgetMachE]

Here is the corrected version that includes the full length of the webinar:

thank you again for doing this and putting up with us bugging you about it

 

[jhalkias]

Is there a probably holding the charge for a longer period at 150? I guess it has been stated that "super charging" will degrade the battery quicker. The key when more EVs get on the road is how quickly they can charge when traveling.

This is a video from Kyle about his Tesla M3 that has a lot of useful information on battery degradation. He drove the car 60,000 miles in a year with a LOT of DCFC. The battery degraded about 8% over that time. Most of us will never approach that kind of DCFC in anything like that period of time. I doubt the several possible times a year road trips for us will do substantial degradation to the battery.

 

[ajmartineau]

I feel like we are having the same conversations/disagreements over and over.

 

[SnBGC]

It was my question. Thanks for the answer, which I'm still a bit fuzzy on. ?

Are you saying that, under certain circumstances, "scavenged" heat from the high voltage battery thermal management system "can be" available to the cabin heat loop?

I understand all the other stuff, e.g. this only works in a relatively narrow range of ambient temperature conditions. Also, that using the seat heaters is more energy efficient than using whole cabin heating.

On the central California coast, we rarely get below freezing, so most calls for cabin heating would be between outside temperatures of 32-60°F.

That is okay. I am a bit fuzzy too. Still going through the patent description of operation and it's pretty hard to follow. Same thing happened to me when I was trying to comprehend how the thermal management system works on the FFE (designed by Magna International)

So far, it sound like the two systems are very similar.....however I am still trying to determine if the front loop(s) are connected to the rear loop.

I will spend some more time going through the information I have and see if I can figure out more stuff....

 

[dbsb3233]

Darren addressed this in his audio as well, saying something like as the battery heats up you can't continue to charge at the maximum rate, so it slows. He said all cars have such a curve. However, he did scoff at those who only hit their maximum briefly.

I guess it depends on their definition of "briefly". Here's what Heiser said back in December...

Mach-E will charge at 150 kw—briefly. Early materials about the Ford Mustang Mach-E haven’t been entirely clear if that vehicle will fast-charge at 150 kw, or whether it just needs 150-kw fast-charging hardware to charge at its peak rate somewhat less than that. Heiser verified that it indeed does charge at 150 kw, but only for a small window of time and state of charge. “At our price point it’s a position of strength,” Heiser said.

https://www.greencarreports.com/new...-how-project-went-from-milquetoast-to-mustang

 

[dbsb3233]

Average range gained will be 61-52 miles / 10 minutes over a period of ~40 minutes. This works if the range is like 350 miles for RWD and near 320 miles for AWD.

I don't see how the MME can hold 150kW like the e-tron to 80%. That doesn't make sense to me.

Trying to measure it in miles complicates it further. An increase there could be from either faster charging (kWh added per period of time), or from better mileage (miles/kWh). Or both.

Since mileage will vary dramatically based on speed and other factors, I'm more interested in seeing the charge taper curve on a pure power basis (kWh and SOC). Then we can translate that to miles based on the speed we're interested in (for me it's high speed interstate).

 

[SnBGC]

The problem is heat. Charging a rechargeable battery produces heat, and too much heat damages the battery. Slower "trickle" charging causes little heat. But crank the power up to charge faster and the heat increases.

From what I understand, it also increases the fuller the battery gets. Has to do with the way batteries work. In a simplistic sense, the more electrons they fill up with, the less "space" to jam more in, and the more heat created (that's a crude description but it gives you the idea). That's why the power level is tapered down the fuller the battery gets.

The longer you charge at maximum the hotter the battery gets. Darren mentioned that last night. You can help this with good battery temperature management but there are physical limits on this. If Ford keeps the rate near 150 kW for a large portion of the charging curve, it will be largely due to improved battery management (hardware and software).

This is a potential issue with Tesla moving to a physically larger battery cell. The tendency to heat up rises with higher volume cells. The ability to cool them rises with higher surface area. You can counter this with increasing the material that serves as heat syncs to allow heat to move from the inside of the cell to the outside but that adds weight and bulk. This is the reason animals in the tropics tend to be smaller than animals at high latitudes. Canadian deer are huge. Florida deer are tiny. Elephants combat the heat with large heat syncs (their ears) and special behaviors.

Average range gained will be 61-52 miles / 10 minutes over a period of ~40 minutes. This works if the range is like 350 miles for RWD and near 320 miles for AWD.

I don't see how the MME can hold 150kW like the e-tron to 80%. That doesn't make sense to me.

I don't want my car charging at 150kW to 80%. That would be very hard on the battery.

I think all these comments are correct and valid.
Perhaps it would help if we understand what is really happening during a DCFC event. When charging a battery, the battery has to be lower voltage than the component doing the charging. HVB voltage is not stable. It has a voltage range so when SOC is low...the HVB is at the lower end of that range. When SOC is high....the opposite.

So, when we pull up to a DCFC station....our SOC is pretty low. The vehicle communicates with the charger and determines voltage and current requirements. The vehicle manages this and then communicates with the charger to throttle up or down. When resistance is low there is less heat. In the most basic form......if battery voltage is low, and the charger voltage is high then not much resistance therefore less heat.

As the battery voltage increases....so does resistance and therefore the heat is greater. The on board systems are pretty good at managing heat but they have a thermal limit.....especially while parked with only a little bit of airflow across the condenser in a hot parking lot with a heat soaked battery because the driver was doing 85 mph down the motorway.

One analogy might be to fill up a balloon with water and then connect it to another empty balloon with a straw. Lay them both on the table, the full balloon will fill the empty balloon pretty quick at first. Then as the pressure (voltage) equalizes the transfer of water will slow down.

Remember, the vehicle software controls the charging speed. This is true with L1 and L2 but those are usually a non issue because that is basically slow charging and the heat generated is very manageable. DCFC is different. MUCH more heat generated so the software looks at all sorts of data points and will slow down the charge rate if temps climb out of range. The charge 'curve' is consistent as long as the conditions are the same from one charge event to the next.

What is comes down to is that we each are going to have to test it out for ourselves for our own needs. Larger batteries are different than smaller batteries. Two motors, one motor all make a difference. There are a bunch of variables to consider.

And......
Wait until you guys see how the MME helps you predict your range. I have some preliminary info from one of the software engineers and it's cool stuff. It will actually tell you if you are going to make it to your next charge point based on your current speed. If you have miles to spare....it will show that to you as well. If you don't or are too close for comfort then you can slow down and/or turn off your climate control and see your range increase. It is that dynamic. It won't take very long until you get to learn your car and feel comfortable going out on the open road.

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