Battery charged to 90% ... NOT!

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dliunatic

dliunatic

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Hmmm. I’d encourage you to take it in and have the dealer look at it. You will at least have a record of your issue.

Id ask them to look at the individual cell SOC across the pack and look for any soft cells. If they are all fine then maybe it’s the GOM algorithm not liking something you do. If you do have a few soft cells you will want to know that as a potential warranty issue.
Yea... I suspect it's something to do with rebalancing after they replaced 2 cell modules from the previous round. ?
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Back in August my car started dropping 3-4% immediately after I pulled it off my charger. I just dealt with it for a couple of weeks. Then my car broke down on me with a high voltage battery fault and had to be towed. Ended up 2 of my battery modules were bad and had to be replaced. I thought about taking it in to the dealer when the % issue was happening and never did. Not sure if they would have found anything or if I could have avoided being broken down at Costco on a Sunday.
 

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I just checked the SOC using OBDII app for Ford HVB and the app says the SOC is 88% and the car says 93%. So if 88kw is the usable capacity of the battery and SOC is 88.7% shouldn't I have 78kw available instead of the battery showing 72.53 kw to empty?
Ford Mustang Mach-E Battery charged to 90% ... NOT! Screenshot_2021-11-11-13-37-43-707
Ford Mustang Mach-E Battery charged to 90% ... NOT! IMG_20211111_133823
 
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I just checked the SOC using OBDII app for Ford HVB and the app says the SOC is 88% and the car says 93%. So if 88kw is the usable capacity of the battery and SOC is 88.7% shouldn't I have 78kw available instead of the battery showing 72.53 kw to empty?
Agreed, clearly something isn't right here. It could be a firmware issue that is providing the incorrect battery percentage for both the ODBII app and what is shown in the car. The ODBII app might be pulling the data from a different source than the car. They could be looking at the same data source, but the car or the app could be manipulating the raw value before displaying it on screen.

Without knowing how the sausage is made we can only speculate ?.
 

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Agreed, clearly something isn't right here. It could be a firmware issue that is providing the incorrect battery percentage for both the ODBII app and what is shown in the car. The ODBII app might be pulling the data from a different source than the car. They could be looking at the same data source, but the car or the app could be manipulating the raw value before displaying it on screen.

Without knowing how the sausage is made we can only speculate ?.
There are two SoC parameters, the "real" SoC used for internal calculations, and the "displayed" SoC which is what you see on the screen. The buffer is programed into the displayed SoC calculation. So for example, when you charge the car to 100% displayed, the real SoC is probably ~95%. Likewise if you drain it down to 0% on the display, the real SoC would be ~5%.

Functioning as designed, not a bug.
 


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There are two SoC parameters, the "real" SoC used for internal calculations, and the "displayed" SoC which is what you see on the screen. The buffer is programed into the displayed SoC calculation. So for example, when you charge the car to 100% displayed, the real SoC is probably ~95%. Likewise if you drain it down to 0% on the display, the real SoC would be ~5%.

Functioning as designed, not a bug.
I charged to 100% last night the reported battery per the OBD is showing available 79.5 Kw, the car is supposed to have near 88Kw when full charged, the battery is 99kw with 11kw split between top and bottom to keep the battery from being damaged. 88 Kw usable is what I was told.
 
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I charged to 100% last night the reported battery per the OBD is showing available 79.5 Kw, the car is supposed to have near 88Kw when full charged, the battery is 99kw with 11kw split between top and bottom to keep the battery from being damaged. 88 Kw usable is what I was told.
Mind sharing what tool you are using for ODB reading? I charged mine to 100% last night and it quickly went to 95% as I pulled out of the driveway. My GOM says 227 when fully charged and freshly reset. I would expect that to be 250 for an ER that's been reset. Something doesn't seem right, definitely worried about my longer trips this weekend.
 

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Mind sharing what tool you are using for ODB reading? I charged mine to 100% last night and it quickly went to 95% as I pulled out of the driveway. My GOM says 227 when fully charged and freshly reset. I would expect that to be 250 for an ER that's been reset. Something doesn't seem right, definitely worried about my longer trips this weekend.
One of the apps is called "Car Scanner ELM OBD2", the other is called "Ford HVB (battery diagnosic app)" these are Android apps.
 

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Car Scanner ELM OBD2 works on iOS, too.

"Energy to empty kWh" is probably an underestimation, and the number fluctuates quite a bit (charging, driving). We probably need more tests, maybe someone can drive to 0% SOC?
 
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wings2063

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Car Scanner ELM OBD2 works on iOS, too.

"Energy to empty kWh" is probably an underestimation, and the number fluctuates quite a bit (charging, driving). We Need more tests.
What I find interesting is that 90% of 88Kw is 79.2Kw. Almost looks like Ford fixed it so in reality you can't charge over 90%, since the OBD report at 100% SOC 79.5Kw available.
 

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After 2 separate charging sessions to 90% my SOC dropped by 5% by the time I left my driveway. On the 3rd charge I forced a charge to 100%. I left for the day and no crazy SOC drops like before. On the 4th charge I went back to my usual 90%. In this case I had no issues with my SOC dropping by 5% like it did before.

I'm not sure what happened, maybe charging up to 100% did some type of recalibration to fix the issue. I haven't charged to 100% in probably 4 months. Hopefully that addresses the problem.
 
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After 2 separate charging sessions to 90% my SOC dropped by 5% by the time I left my driveway. On the 3rd charge I forced a charge to 100%. I left for the day and no crazy SOC drops like before. On the 4th charge I went back to my usual 90%. In this case I had no issues with my SOC dropping by 5% like it did before.

I'm not sure what happened, maybe charging up to 100% did some type of recalibration to fix the issue. I haven't charged to 100% in probably 4 months. Hopefully that addresses the problem.
Did you do the 100% charge on slow charge via the Ford charger?
 

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Could this also be temperature related? I.e. the battery charges (getting warm in the process) and then stops at 90% in the middle of the night. Then say the next morning after the battery has cooled down to ambient and when the car is woken up and turned on, cell voltage is checked again and measures lower compared to when it stopped charging when the battery was warm? Maybe there is an algorithm that trys to compensate for calculating soc from voltage as battery temperature changes, but it may not be perfect.

After it drops to 87%, if you charge to 90% again for a few mins and then immediately drive it as soon as it gets to 90%, does it stay at 90% or does it drop to 87% again?
 

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Could this also be temperature related? I.e. the battery charges (getting warm in the process) and then stops at 90% in the middle of the night. Then say the next morning after the battery has cooled down to ambient and when the car is woken up and turned on, cell voltage is checked again and measures lower compared to when it stopped charging when the battery was warm? Maybe there is an algorithm that trys to compensate for calculating soc from voltage as battery temperature changes, but it may not be perfect.

After it drops to 87%, if you charge to 90% again for a few mins and then immediately drive it as soon as it gets to 90%, does it stay at 90% or does it drop to 87% again?
I think I know what you're getting at. That sounds analogous to how tire pressure is impacted by temperature. I haven't done enough research on the specifics on how temperature impacts the battery. You could be on to something regarding the calculation of the SOC. I tend to lean towards some type of software/firmware issue as well.

@dliunatic Also note the issue came back again just this morning. I charged to 90%, unplugged in the morning, and SOC dropped 4% by the time I left the driveway, and another 1% 10 seconds later.
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