Excellent Q&A with Ford/Mach-E Electric Vehicle Engineer

[TheBluf]

The question above refers to the set points for 0 and 100%. You can't (and shouldn't) fully discharge these batteries (doing so would be damaging to the battery). Almost all electric car batteries have a reserve to prevent that from happening. Tesla just uses a very small reserve.

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[silverelan]

Seems like 150kW is their comfortable limit for DC fast charging but it's still not clear to me if it's wired for up 350kW. From the "non-answer" response, seems like there's room for increased speeds but concern about frying the batteries over the long term.

For those who don't follow long term DC fast charging implications, Bjorn Nyland of YouTube has done several stories now of how Tesla has a lifetime limit on maximum DC fast charging energy. Once the limit has been reached, the car will throttle the charging speed permanently.

 

[Whatstreet]

I assume "MUCH more conservative" is referring to where they set the 0% and 100% set points within the real range of the batteries. Sounds like Tesla usually sets that quite liberally in order to advertise greater range, but at what cost? Maybe their more advanced battery architecture can handle more with less "damage"?

I guess we'll just have to see, but it would be nice to find out more details so as to have an idea of what true practical range is on the Mach-e. By that, I mean is it significantly damaging to charge to 100% and run it to 0%? Or have they already built so much buffer into those 0% and 100% set points that we shouldn't even bother trying to limit it to 10%-80% most of the time?

Also, will it go below 0% at all? If yes, how far (est), and how damaging is it? While we certainly wouldn't plan to go below that, knowing it's there goes a long way to determining how much practical range there is. Same way in a gas car. If I know there's a 2 gallon (~50 mile) reserve when the tank reads E, I'm willing to take it to E. If not, the practical bottom is more like 1/8th.

Those are good questions but since the manufacturer wont tell you it will take empirical observations to estimate it. There are people who abuse their Tesla batteries and they have measured maybe 5% degradation in a year. That's using DCFC exclusively and discharging to near zero and charging to near 100%. Tesla recommends charging to 80% when possible. Most EVs don't limit charge and discharge like the Chevrolet Volt does. You cant fully discharge it or 100% charge it, that was not carried over to the Bolt which has little margin if any.

An analogy for all this is gas mileage claims, under ideal conditions a claimed range can be achieved but not in many real world scenarios. Tesla's new range claim for the Y is based on a consumption rate of something like 4.1 miles per kWh. I bet it will do it but not at 75 miles per hour with the heater blasting. Range wont be as important with more charging opportunities/locations but for now my advice is get the big battery.

 

[dbsb3233]

Those are good questions but since the manufacturer wont tell you it will take empirical observations to estimate it. There are people who abuse their Tesla batteries and they have measured maybe 5% degradation in a year. That's using DCFC exclusively and discharging to near zero and charging to near 100%. Tesla recommends charging to 80% when possible. Most EVs don't limit charge and discharge like the Chevrolet Volt does. You cant fully discharge it or 100% charge it, that was not carried over to the Bolt which has little margin if any.

An analogy for all this is gas mileage claims, under ideal conditions a claimed range can be achieved but not in many real world scenarios. Tesla's new range claim for the Y is based on a consumption rate of something like 4.1 miles per kWh. I bet it will do it but not at 75 miles per hour with the heater blasting. Range wont be as important with more charging opportunities/locations but for now my advice is get the big battery.

Oh for sure, that 2nd paragraph is a whole nother layer on top of it (hefty range degradation at highway speeds (ironically, where we actually need range), using climate control, in hot or cold weather, etc.). While ICE vehicles see a loss of MPG efficiency in those conditions too, it's a tiny fraction of what it is for BEVs (like 10% vs 30%).

It would just be helpful to know much (if any) we should plan to limit ourselves on the ends. The more conservative they are are building in buffers on each end, the less self-limiting we should have to do, and the more of that advertised range we should be able to get. I guess as first year buyers, we're just gonna have to trust what Ford recommends. Really won't be able to tell real-world degradation for years anyway.

But more to the point -- it's helpful in planning whether to get the SR or ER battery, or for that matter to get a BEV at all, since real-life practical range is a huge data point in the purchase decision.

 

[Whatstreet]

Oh for sure, that 2nd paragraph is a whole nother layer on top of it (hefty range degradation at highway speeds (ironically, where we actually need range), using climate control, in hot or cold weather, etc.). While ICE vehicles see a loss of MPG efficiency in those conditions too, it's a tiny fraction of what it is for BEVs (like 10% vs 30%).

It would just be helpful to know much (if any) we should plan to limit ourselves on the ends. The more conservative they are are building in buffers on each end, the less self-limiting we should have to do, and the more of that advertised range we should be able to get. I guess as first year buyers, we're just gonna have to trust what Ford recommends. Really won't be able to tell real-world degradation for years anyway.

But more to the point -- it's helpful in planning whether to get the SR or ER battery, or for that matter to get a BEV at all, since real-life practical range is a huge data point in the purchase decision.

I agree the manufacturers are enabling the operator to increase the rate of degradation by not applying more conservative limits to the usable range of battery voltage. We don't know what Ford has done regarding this, but I know what GM did with the Bolt. The margins for that car are much more liberal than they are for the Volt. Its about a 60kWh battery. It's not an 80kWh battery with 60kWh usable range. My guess is Ford isn't going to sell a really big battery then limit the usable range by much. That will be left up to the operator.

 

[dbsb3233]

The question above refers to the set points for 0 and 100%. You can't (and shouldn't) fully discharge these batteries (doing so would be damaging to the battery). Almost all electric car batteries have a reserve to prevent that from happening. Tesla just uses a very small reserve.

Understood, and of course we should never run it to the "fully discharge" point. My point was about how much bigger that reserve is on the Mach-e (both programmed, and recommended usage). If, for instance, it's recommended that we don't go below the 20% reading on the display, that changes our real-world expectation for range. But if Ford is already building in a large buffer, maybe it's fine to run it to 0%. Makes a big difference on deciding whether the vehicle has enough range or not when deciding to purchase it.

 

[Whatstreet]

Understood, and of course we should never run it to the "fully discharge" point. My point was about how much bigger that reserve is on the Mach-e (both programmed, and recommended usage). If, for instance, it's recommended that we don't go below the 20% reading on the display, that changes our real-world expectation for range. But if Ford is already building in a large buffer, maybe it's fine to run it to 0%. Makes a big difference on deciding whether the vehicle has enough range or not when deciding to purchase it.

I'm sure that there are some limits. LiFo batteries are destroyed if discharged to 0V. They wont let you do that. My bet is they haven't really decided where to set it yet.

 

[Billyk24]

Oh for sure, that 2nd paragraph is a whole nother layer on top of it (hefty range degradation at highway speeds (ironically, where we actually need range), using climate control, in hot or cold weather, etc.). While ICE vehicles see a loss of MPG efficiency in those conditions too, it's a tiny fraction of what it is for BEVs (like 10% vs 30%).

It would just be helpful to know much (if any) we should plan to limit ourselves on the ends. The more conservative they are are building in buffers on each end, the less self-limiting we should have to do, and the more of that advertised range we should be able to get. I guess as first year buyers, we're just gonna have to trust what Ford recommends. Really won't be able to tell real-world degradation for years anyway.

But more to the point -- it's helpful in planning whether to get the SR or ER battery, or for that matter to get a BEV at all, since real-life practical range is a huge data point in the purchase decision.

My 2017 Ford CMax energi has a 7.0 kWh battery but 5.6 kWh is usable at new. 20% buffer? I don't believe the Mach e needs that much buffer as it has liquid cooling and the CMax cabin air cooled which I'd deficient for summer heat.

 

[dbsb3233]

My 2017 Ford CMax energi has a 7.0 kWh battery but 5.6 kWh is usable at new. 20% buffer? I don't believe the Mach e needs that much buffer as it has liquid cooling and the CMax cabin air cooled which I'd deficient for summer heat.

Yeah I threw out 20% just to make it a clear example, but I would hope any recommendation to not go below would be no higher than 10%. Hopefully 0% if they're being as conservative and adding as much buffer as the interview suggests.

But I was equally as interested in the upper end, i.e. whether it will be recommended to only charge to something like 80% most of the time, or whether they'll be building in a big buffer on that end too.

 

[dbsb3233]

Could be. Not even sure how many people here have put down the $500 deposit. I would guess most but hard to say.

I'm more curious to see what Ford's follow-thru rate will be for people that placed a deposit. I'm guessing something around 75%. There will surely be a chuck that choose not to buy. In part because it sounds like the deposit automatically refunds from Ford (making it easy to just not bother with the dealer purchase). But also for a number of other reasons, like new competition being announced (or found out about by people that didn't realize it existed to begin with), or simply finding out more about the whole BEV experience (good and bad) relative to ICE driving. As you say, some probably have different expectations that can't be met as they learn more about it.

That's where a forum like this really comes in handy - as a way to learn. When making a $50k-$60k vehicle purchase, it's a good idea to know just what you're getting for that hefty price.

 

[highland58]

If your charger will show you the amount of charge that is used, like a juicebox with wifi and phone app does, that can be compared to the rated size of the battery to judge the buffer size, although to get an accurate number you need to get close to zero before charging. When I run my PHEV to zero and charge to full, I get 14kwh of charge on my battery that is rated at 17kwh, so approximately a 3kwh buffer.

 

[Billyk24]

If your charger will show you the amount of charge that is used, like a juicebox with wifi and phone app does, that can be compared to the rated size of the battery to judge the buffer size, although to get an accurate number you need to get close to zero before charging. When I run my PHEV to zero and charge to full, I get 14kwh of charge on my battery that is rated at 17kwh, so approximately a 3kwh buffer.

About 22% buffer. 17kWh PHEV is what vehicle?

 

[timbop]

About 22% buffer. 17kWh PHEV is what vehicle?

based on his sig, I'd say 2018 honda clarity

 

[dbsb3233]

I don't think the charging curve for the Mach-e has been released yet. Many people are anxiously awaiting it.

Ford advertises the charge rate (presumably max) at 47 miles per 10 minutes on a 150 kW DCFC charger.

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