Battery Thermal Bottleneck Suspicions / Slow Charging [by InsideEVs]

[jjhenry]

https://insideevs.com/news/543122/mustang-mache-battery-slow-overheating/


I'm glad I went with Options. If they come out with a better battery pack in a few years, I'll trade in for the newer model.

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[Carsinmyblood]

The Mach-E pack’s thermal bottleneck also explains its overheating problem when driven “unbridled.” Track-style performance driving involves repeated hard acceleration and heavy braking, including regenerative braking. If those driving cycles repeatedly push or pull over 100 kW into or out of the pack (and with the GT’s 480 HP of motor power and a lead foot, that is easy to do), the cell internal resistance heat will exceed the conductive heat path’s ability to remove it. Cells will quickly heat up beyond their high-temperature limits & the pack will go into reduced propulsion mode.


Ok... but who drives like that?

 

[Mach-Lee]

https://insideevs.com/news/543122/mustang-mache-battery-slow-overheating/


I'm glad I went with Options. If they come out with a better battery pack in a few years, I'll trade in for the newer model.

Interesting article, but I find his analysis somewhat flawed. First, he's basing his calculations off what he saw in a Munro video rather than taking actual in-person measurements. He doesn't emphasize that it's a very rough model/estimate. It's sort of a WAG to me. I do not agree with his conclusion that the VW battery is better, he's relying on there being good thermal contact at the bottom fo the cell pouch where all the foil edges terminate, which could create a thermal bottleneck in and of itself. Extracting heat out the side of the cell is much better IMO because of greater surface area, and the distance from all parts of the cell to a high thermal conductivity surface is reduced. The plastic on the bottom of the Mach-E cell is likely there deliberately to reduce direct contact and make the temp from the bottom to the top of the cell more even, I do not think that is necessarily a flaw. The plastic carriers also have to be there to allow for cell swelling and keep that under control so the cell separators aren't damaged.

If anything, we can conclude that the Mach-E battery (which was likely engineered mostly by LG) is designed for even cell temps, maximum range, and extreme ambient temp performance at the expense of raw heat transfer ability. Thickening the Al plates between cells would increase heat transfer rate, but it would also make the battery modules wider and heavier, meaning less room for cells and reduced range. The design seems optimized for everyday use with occasional fast charging and performance use, which I believe were the design targets for the Mach-E.

I'm still not convinced more can be done with software to extract more performance out the current design, it seems apparent that Ford has chosen to be extremely conservative with the battery to minimize stress and maximize longevity.

Perhaps in the future the GT will get a different battery with much heftier thermal specs to support continuous track use, but it will have to come at the expense of range if the battery footprint remains constant.

The "thermal ribbon" design of the Teslas is outstanding from a thermal perspective, but is more costly, difficult to manufacture, and takes up more space in the pack. More connections and leak points than a coldplate design. Ford does not have the volume yet to make that sort of design cost effective, but it will be interesting to see the thermal design on the F150 since that is expected to go into large volume production.

 

[silverelan]

I'm still not convinced more can be done with software to extract more performance out the current design, it seems apparent that Ford has chosen to be extremely conservative with the battery to minimize stress and maximize longevity.

Ford's BEV compliance car program was already well underway when they did the direction change into the current MME. It wouldn't surprise me if the limitations we're seeing are because the battery pack is a carryover from the original design specs and is now being asked to do work far beyond what a front wheel drive crossover would ever expect.

 

[Jeffvisor]

Mustang Mach-E Battery Charges Slowly, Overheats Quickly: Why? (insideevs.com)


To its credit, Ford is exploring the various slow-charging/over-heating issues and seeking improvements. It's promised a software update that will extend the higher-speed charging rates beyond 80% SOC, and possibly bump up the maximum initial kW charge rate.

Also, Ford is exploring “unbridled” drivetrain power-management software tweaks to modulate repeated hard-acceleration power demands, thereby reducing pack heating and extending track-style driving times. But software tweaks treat symptoms and do not resolve the root cause: The current Mach-E pack’s hardware-based thermal bottleneck – the plastic-carrier/passive-fin based module design – is baked in.

 

[Mach 5e]

Here's just one of many threads about this article.

https://www.macheforum.com/site/threads/battery-thermal-bottleneck-suspicions-by-insideevs.10765/

Not to over react but this appears to be a significant flaw (LG - FORD - LG). Sandy Munro and other reports laid it out well. Software can only bandaid this, the more I look at the issue the more I see a revised design and manufactured battery replacement as the only real solution, perhaps with 3 heat trans plates outer-inner-outer sandwich type? Tesla had experienced forms of this early on as they covertly replaced a lot of battery packs due to excessive charge cap degradation.

I have 2000 miles on my Premium Standard RWD and I exclusively home charge (Level2 Juice Box) in Honolulu and there are no road-trips, so Im likely the type of owner least impacted. I'm guessing the standard battery and RWD. (only one motor drawing) has the same cooling capacity as the Extended battery, AWD, and possibly even GT. The worst impact on usability is going to be to those who remote - away from home charge, performance models, and aggressive driving habits. This is a core level gut punch to the GT's.

Just my processing so far,
Devon

 

[Timelessblur]

To be blunt that article is FUD. The entire argument is based on a screen grab from the tear down. It is not based on talking to anyone but based on a screen grab. The table of the "bottle neck" might as well be treated as made up numbers as it is not based on facts. It is 100% a click bait article and the author should be called out for his crap work. My dogs shit is worth more than those words. It is all hear say and not based on reality. It would be different if it was based on facts but instead it is based completely on hear say and a screen grab.

 

[Mach 5e]

To be blunt that article is FUD. The entire argument is based on a screen grab from the tear down. It is not based on talking to anyone but based on a screen grab. The table of the "bottle neck" might as well be treated as made up numbers as it is not based on facts. It is 100% a click bait article and the author should be called out for his crap work. My dogs shit is worth more than those words. It is all hear say and not based on reality. It would be different if it was based on facts but instead it is based completely on hear say and a screen grab.

The discovery process often begins with consumer experiences, deductive reasoning, and in-depth R&D on the issue. That appears to be what is evolving. Discounting the ground work as anything but a discovery process is counter productive IMO.

 

[Timelessblur]

The discovery process often begins with consumer experiences, deductive reasoning, and in-depth R&D on the issue. That appears to be what is evolving. Discounting the ground work as anything but a discovery process is counter productive IMO.

My issue with it is how he wrote it and why I am calling it FUD. It is a great hypothise and a great starting point but that not how it was written. Inside EV and Kieth Ritter presented it as this was fact. 100% fact. No real work was done all from a screen grab. Hence why I am calling it a click bait FUD piece of work. It is crap. It should be treated as such.
If the author had written as a theory and came at it from that point of view it would be different. My issue is he came at as this is fact and then put up made up tables to look like it was all true.
So yes I vote treat both InsideEV and Keither Ritter as putting up click bait FUD and calling them out for their horrible work here.

 

[Mach 5e]

My issue with it is how he wrote it and why I am calling it FUD. It is a great hypothise and a great starting point but that not how it was written. Inside EV and Kieth Ritter presented it as this was fact. 100% fact. No real work was done all from a screen grab. Hence why I am calling it a click bait FUD piece of work. It is crap. It should be treated as such.
If the author had written as a theory and came at it from that point of view it would be different. My issue is he came at as this is fact and then put up made up tables to look like it was all true.
So yes I vote treat both InsideEV and Keither Ritter as putting up click bait FUD and calling them out for their horrible work here.

Thank you for your grounded reply. I was impressed by Munro's dissection of the various actual battery packs unless I misunderstood the images. The diagrams helped interpret the real images. As irritatingly slow and choppy Munro can be, the mostly unbiased professional opinions he report are pretty convincing. I first noticed this evolving issue when owners were complaining about charging rate dropping off to a crawl long before 90%, then the first drag runs with low MPH, now this.....
Going to be an interesting discovery process

 

[JimmyMachE]

Actually, Bjorn Nyland on a 1000km trip noticed that Mach-E battery maintains pretty high temperature even after DC charging:

 

[BMT1071]

Thank you for your grounded reply. I was impressed by Munro's dissection of the various actual battery packs unless I misunderstood the images. The diagrams helped interpret the real images. As irritatingly slow and choppy Munro can be, the mostly unbiased professional opinions he report are pretty convincing. I first noticed this evolving issue when owners were complaining about charging rate dropping off to a crawl long before 90%, then the first drag runs with low MPH, now this.....
Going to be an interesting discovery process

Did he actually provide any information in those videos you reference? I watched a few of the early MME videos he did, but then I gave up on him. Any time he saw something he didn't understand all he said was "I wonder why Ford did that?". No shit, Sandy. Your audience might wonder as well, and as the producer of a video you should be researching and presenting answers. Every video reminded me of a fashion show or design reveal where all you get is first-look off the cuff remarks.

 

[SnBGC]

Ford's BEV compliance car program was already well underway when they did the direction change into the current MME. It wouldn't surprise me if the limitations we're seeing are because the battery pack is a carryover from the original design specs and is now being asked to do work far beyond what a front wheel drive crossover would ever expect.

Perhaps.
Even so, this battery pack design fares much better then the FFE packs when it comes to cooling. My FFE asked to be plugged in at 97 degrees ambient and would almost always begin cooling the battery after a drive. The MME went much deeper into the summer before it would ask to be plugged in and even then it wouldn't always begin cooling right away.

Charging speeds are much faster as well. So if the pack design is a carry-over from the compliance designs then it seems to still work for my use case. I would like Ford to update the programming to allow battery cooling while parked on plug outside the charge schedule. That one change would help me out quite a bit. Everything else I am fine with, charging speeds are good, discharge rates are good, battery cooling is good.

 

[silverelan]

Perhaps.
Even so, this battery pack design fares much better then the FFE packs when it comes to cooling. My FFE asked to be plugged in at 97 degrees ambient and would almost always begin cooling the battery after a drive. The MME went much deeper into the summer before it would ask to be plugged in and even then it wouldn't always begin cooling right away.

Charging speeds are much faster as well. So if the pack design is a carry-over from the compliance designs then it seems to still work for my use case. I would like Ford to update the programming to allow battery cooling while parked on plug outside the charge schedule. That one change would help me out quite a bit. Everything else I am fine with, charging speeds are good, discharge rates are good, battery cooling is good.

If the InsideEVs analysis is to be believed, then the pack wasn't designed for high performance but instead, it's meant for dependability and longevity with 1C recharging capability.

A FWD crossover EV with 300 miles of range and 1C average charging for a half hour in 2017 was a respectable target.

 

[SnBGC]

If the InsideEVs analysis is to be believed, then the pack wasn't designed for high performance but instead, it's meant for dependability and longevity with 1C recharging capability.

A FWD crossover EV with 300 miles of range and 1C average charging for a half hour in 2017 was a respectable target.

Agreed. I would take dependability and longevity over high performance since this is my daily driver.

Anyone know what battery pack is in the 1400 Mach-E? Same as our cars?

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