Discovered: GTPE Delivers 5 Seconds of Full Power on Acceleration Then Reduces Battery Power to Limit Heating

[Zathras]

Do the non-GT models have a similar power reduction after ~5 seconds, or do they maintain full power (or nearly full power) for a longer time? Specifically, does anyone know if the non-GT models actually make more effective power than a GT, once the GT pulls power back at higher speeds (80-100)?

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[JcMarin]

Do the non-GT models have a similar power reduction after ~5 seconds, or do they maintain full power (or nearly full power) for a longer time? Specifically, does anyone know if the non-GT models actually make more effective power than a GT, once the GT pulls power back at higher speeds (80-100)?

Well, based on the TRAP times on the 1/4 mile for both being practically the same, I would say that after the 5 seconds the GT becomes a regular MME 4X for a while

 

[Mach1E]

Do the non-GT models have a similar power reduction after ~5 seconds, or do they maintain full power (or nearly full power) for a longer time? Specifically, does anyone know if the non-GT models actually make more effective power than a GT, once the GT pulls power back at higher speeds (80-100)?

The regular models appear to have more linear power delivery, without a steep drop off.

No mention of a 5 second boost anywhere (unless it’s hidden deep in a European press release somewhere).

 

[Jimmy2]

It's the exact same car, they won't.

From everything I've seen so far, looks like you are right. I'll hold on to my AWD X for a while longer, but once the Ford Engineers figure it out, once the GTPE can compete with the MYPE in the 1/4 mile, that is day I trade up.

 

[voxel]

This explains why I've heard the Mach-E cells compared to the Bolt (same design).

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

Also explains why the ID.4 fires battery coolant pump warnings (many false positives). It's a more complicated design.

 

[dtbaker61]

This explains why I've heard the Mach-E cells compared to the Bolt (same design).

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

Also explains why the ID.4 fires battery coolant pump warnings (many false positives). It's a more complicated design.

sure does explain the issue .... a plastic footplate on the cell carrier slowing thermal conductivity! Not good for an EV.

The 'race mod' just got a lot harder ... we'd have to pull apart battery pack and replace cell carriers with all - aluminum web/feet sitting on the chiller plate, or goop in thermal paste between every other carrier hoping for better transfer. AL web between every pouch would be best.

or..... Performance Prep could include adding a monster chiller capable of lowering the chill plate temp, more heat transfer with larger delta T. Not as effective as fixing the cell carrier design.

Or.... perhaps there will be a 'performance' battery pack that could be purchased and swapped in... MAYBE even taking the original as a trade-in since the cells would all still be fine. Or a ''race prep' service to pull apart your pack, replace carriers, and re-install.

Sort of like the equiv of a crate motor race tuned.

 

[ab13]

sure does explain the issue .... a plastic footplate on the cell carrier slowing thermal conductivity! Not good for an EV.

I would say it depends on the thickness of the plate used relative to the heat it needs to transfer. The plastic foot doesn't interfere with the heat transfer and is needed for the structure to stand vertically. However, they could have used a thicker aluminum plate or two smaller plates in opposite directions, still allowing the plastic to stand the package upright along the ends. I don't see the bottom edge of the battery pouch to be flat enough to contact well without a lot of thermal interface paste.

 

[voxel]

sure does explain the issue .... a plastic footplate on the cell carrier slowing thermal conductivity! Not good for an EV.

Also explains the "low" 0.9C charge rate used by Ford compared to 1.2C to 1.5C of the ID.4 and the 1.9C average of the Ioniq5/EV6 (albeit these cars have some thermaling issues too - we need to see some battery cooling diagrams).

Charging and discharging are correlated. If 1C charging heats up by 4 degrees C on the Mach-E. To get the 250 kW power you see in the acceleration charts from 50-80mph (I believe the data is referenced in this thread) that is basically 2.5C to 3C which raises the battery pack's temperature significantly in the hotspots.

 

[Sitdown]

No guessin’ here - I’ve been taking many logs of system performance and battery and coolant temperatures. I’ve never seen the battery over 32C and that was after two hours of fast ascending many thousands of feet of elevation. Many of us have been collecting data for a while now.

Check out the data logs here if you want to take a closer look. I periodically post more: https://www.macheforum.com/site/threads/driving-dynamics-and-charging-data-files.8473/

The MachE does have active cooling for the battery system, the nominal inlet temperature at the battery cold plates tends to be around 58F. Each battery module is in a compressed plastic enclosure with an independent cold plate, which is a good design. There is a radiator behind the front lower grill inlets (which open and close as needed), and a supplemental fan to bring in extra air if needed or when charging.

The issue with the 5 second time isn’t overall pack temperature, I’m sure, it is a combination of localized heating and the high overall C-rate.

Also, just to be clear, the MachE does charge at 1.5C at the beginning of the charge cycle, then drops to 1.2 for much of the cycle, and then tapers down to 0.7 or so before hitting the cliff at 80% SOC. It is a bit conservative compared to some other makers, but we are hoping for improvements there.



I’ve ascended 6000 ft at 85+mph and had no thermal issues in my E4X - as I mentioned above I’ve never seen a battery temp over 32C and that was after two hours of aggressive driving at high elevation. Remember that high elevation reduces cooling system performance (less air mass to shed heat into).

I’ve had a few concerns about the front motor temp going too high, since it is the least cooled active component, but everything else, battery, rear motor, and both inverters stay very well cooled, better than I was anticipating.

Check out a few data logs here, and I’m hoping to collect more soon that include the min/max cell temp values which can be a good way of identifying differential cooling problems (finding hot spots). https://www.macheforum.com/site/threads/driving-dynamics-and-charging-data-files.8473/

Ultimately there will always be some limitation on power output vs duration as long as we are on the same basic Li chemistries - my main question is whether that limitation is reasonable or overly conservative, and if there are things that could be done to improve it, such as make it temperature sensitive, or make it a gentler taper rather than a big drop.

Did we get data on a GT or GTPE yet? I made a few attempts at collecting data with lots of b2b pulls, but kept having issues with it recording that data and not the cruise before or after. Fell off the map since, but If we still need GT data, ill PM you to better confirm my process.

 

[dtbaker61]

No guessin’ here - ...

The MachE does have active cooling for the battery system, the nominal inlet temperature at the battery cold plates tends to be around 58F....

The issue with the 5 second time isn’t overall pack temperature, I’m sure, it is a combination of localized heating and the high overall C-rate.

exactly, and thanks for the data!

With Li in most physical battery formats there tends to be thermal limitations when there is more than 1C current regardless of whether it is charge or load. The pouch cells can handle bursts of far more... for a few seconds as we've seen ... but then the must be cooled, or risk damage over time as nasty things start happening internally when there are 'hot spots' within the cell.

Ford's BMS and controller parameters are pretty darn conservative; which is a good thing in first model year to reach warranty life! The intent I'm sure was to gather a bunch of data, and consider loosening the software parameters if temps were looking good.

This leaves us with (at least) three ways to improve Performance:
1. software changes to allow higher temps, at risk of shorter battery life
2. reduce inlet temp of coolant from the current 58 deg F to enable more heat transfer
3. change cell carrier to enable better heat transfer

I think that for the non-factory racer, the most approachable mod would be #2.... to put a 'quick chiller' inline in the plumbing that would reduce the inlet temp circulating from 58 deg down as cold as you could get it.... a typical heat pump is capable of 35-40 deg F, and sized properly could extend the time spent at high C rate without making any changes to software or physical battery.

 

[dtbaker61]

I would say it depends on the thickness of the plate used relative to the heat it needs to transfer. The plastic foot doesn't interfere with the heat transfer and is needed for the structure to stand vertically. However, they could have used a thicker aluminum plate or two smaller plates in opposite directions, still allowing the plastic to stand the package upright along the ends. I don't see the bottom edge of the battery pouch to be flat enough to contact well without a lot of thermal interface paste.

From the article illustration, it looks to me like the existing cell carrier is basically a 'web-truss' or an 'I-beam' with AL web and plastic top and bottom and has pouches on either side. This means heat is transferred down the AL web really well, but hits fairly high thermal resistance with the plastic foot before it hits the thermal paste and chill plate below. This also means that the AL cooling web is only on one side of any given pouch.....

I would consider this design pretty poor from heat transfer perspective, and probably done to save money in mfg by molding plastic carrier around the web rather than welding or bending all- aluminum L shape pouch carriers that would give superior transfer; with an AL web between EVERY cell instead of every other.

 

[Frankie]

Are you saying you think increased cooling ability would automatically make the car "boost" for longer periods of time "without making any changes to software"?

 

[dtbaker61]

Are you saying you think increased cooling ability would automatically make the car "boost" for longer periods of time "without making any changes to software"?

exactly.

I would be amazed if the 'boost' is on any kind of timer...

The software is *likely* set to throttle back on current when battery cell pouch sensors hit some specific temp. If you improve the cooling with better heat transfer, you could run at higher C rate for longer.

you can improve cooling with physical design, or by reducing the inlet temp of the coolant. I'm not a drag racer, but I'd bet that with a little bit of a plumbing, and a cooler full of ice water in the frunk, you could get another couple seconds of full acceleration at the drag strip..... and have a cooler full of cold beer!

https://www.amazon.com/Stainless-St.../B0851STCS5/ref=pd_sbs_6/137-3075184-8366349?

 

[Mach1E]

From everything I've seen so far, looks like you are right. I'll hold on to my AWD X for a while longer, but once the Ford Engineers figure it out, once the GTPE can compete with the MYPE in the 1/4 mile, that is day I trade up.

To be fair, it already does compete in the 1/4 mile. Fastest time for the GTPE so far is 12.2, which matches times we have seen for the MYP.

How it runs the times is a different story.

I still want to see a side by side race. The GTPE should beat it on the launch and be ahead most of the time, then the MYP will blow past it right before the end.

 

[one5460]

To be fair, it already does compete in the 1/4 mile. Fastest time for the GTPE so far is 12.2, which matches times we have seen for the MYP.

How it runs the times is a different story.

I still want to see a side by side race. The GTPE should beat it on the launch and be ahead most of the time, then the MYP will blow past it right before the end.

The fastest time I've seen for the My-P was 11.9. I predict that after 60 mph, the MY-P would pull ahead until the end. The Mach-E would also have to be at close to full charge.

But I agree, a head to head is what's needed.

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