Battery charged to 90% ... NOT!

dliunatic

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Sigh... More battery wonkiness from me. So not sure if anyone else is experiencing this or if it's a residual issue from my HV battery replacement from a couple months back. I've noticed recently that when I charge to 90% through my preferred charge settings schedule, it will charge up to 90% and say that charging is complete, but then when I start the car I can literally see that percentage dropping within seconds by several percentage points. With past charges after the battery replacement, I've seen it go from 90% to 80%. I thought I was going crazy or had some weird schedule set, but today it went from 90% to 86% within the first minute of me unplugging the charging cable and starting my MME without even driving. Before the battery replacement, I never saw this weird percentage dropping issue...

I have tried removing the schedule and resetting it, which seemed to decrease the amount of percentage drop a bit. Tried charging up to 90% again immediately after the drop today and it added an additional 2kW or supposed 3% in another 19 minutes.

Also the odd part is if I charge to 100% I don't notice any weird battery percentage drops.

Anyone else having this issue and did you have HV battery replacements as well? Wondering if there's some battery reset that I need to do or recalibrate?
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when I replace batteries in phones I sometimes have to run it from 100-0 a couple times because it does the same thing you mentioned. The percentage is just a learned value based on the battery condition. You could try to run it from 100-10 a couple times and see if the problem goes away.
 

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Hmm, yes I could maybe see that happening if you have unbalanced or varying capacity cells. GOM is probably updating as the cell voltages settle down after charging.

Dealer should probably take a look with the scan tool and check all your cell voltages to see how balanced or unbalanced they are. You got a completely new pack right, not just a module pair? For your sake I hope the new battery doesn't have bad cells too, you would get to be super unlucky.

Not sure how often you drive the car, but driving daily and charging to the same % every day will help the balancing process, which only occurs when the car is off. If you do that for a week or two things should be pretty well balanced, if not then it's because of cell capacity differences.
 
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dliunatic

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Thanks for the insights! Yeah... I need to drive it more I guess. More of a weekend driver ? Typically I only need to recharge every couple weeks or so.

Only got a module pair replaced not the full pack so hopefully it's just balancing. I'll try to drive it down and recharge again this weekend to see how it does. ?
 

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GOM is probably updating as the cell voltages settle down after charging.
But it's not a GOM issue, is it? GOM is for mileage, and it's reasonable that estimation can be materially inaccurate for various reasons. SOC should be much more objectively and reliably measurable; I understand SOC estimation is also subject to some margin of error, but should be nothing like what OP is seeing.

I think this is a defect, and should be repaired by the manufacturer,
 


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Thanks for the insights! Yeah... I need to drive it more I guess. More of a weekend driver ? Typically I only need to recharge every couple weeks or so.

Only got a module pair replaced not the full pack so hopefully it's just balancing. I'll try to drive it down and recharge again this weekend to see how it does. ?
Have had my SR MME for 2 months and have 1000 miles on it. Like you am settled in on home charging to 90% about every other weekend. I have noticed a 1 to 3% drop from when I pull the charger cable to when I get in the next time for a drive - might only be an hour.
 

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I am by no means an expert here, but my immediate thought when reading your description is the cell balancing. However, I'm not sure I'd be comfortable suggesting that it's something that will sort itself out as you drive.

Whenever modules are replaced in the battery pack, the techs are supposed to go through a very specific process of reviewing the readings across all of the battery packs and make adjustments to balance them out... and then -- if I'm remembering correctly -- they're supposed to leave the car charging overnight and then repeat the process again the following day. If this process wasn't followed correctly or an error was made, it seems like that could cause the behavior you're seeing if the BMS is getting inconsistent readings across the modules.

As Lee suggests, driving and going through some cycles may help some as the BMS may compensate a bit, but especially with this behavior having started after the replacement, it'd be a really good idea to bring it up with the dealer and ask them about the balancing specifically. Where this is a relatively new process for most shops it's entirely possible they missed a step or took some shortcuts to save time.
 

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Run it all the way up to 100% (as indicated on your screen, which is about 95% chemical SOC), and let it sit overnight, then try driving normally and running a few cycles. It does sound like cell balancing is happening, and a bit of a soak at 100% can aid the process.
 

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Thanks for the insights! Yeah... I need to drive it more I guess. More of a weekend driver ? Typically I only need to recharge every couple weeks or so.

Only got a module pair replaced not the full pack so hopefully it's just balancing. I'll try to drive it down and recharge again this weekend to see how it does. ?
Yes, so FYI the balancing only happens for 24-48 hours after your drive the car. If you're only driving on weekends it's only getting balanced once a week instead of daily. Especially with the new cells the balancing is more important. So try to drive it daily for a couple weeks, even just around the block and see if that helps.

Whenever modules are replaced in the battery pack, the techs are supposed to go through a very specific process of reviewing the readings across all of the battery packs and make adjustments to balance them out... and then -- if I'm remembering correctly -- they're supposed to leave the car charging overnight and then repeat the process again the following day. If this process wasn't followed correctly or an error was made, it seems like that could cause the behavior you're seeing if the BMS is getting inconsistent readings across the modules.
Yes, that is true. If the cells are too far different there will be error codes and the car won't drive, then they have to drop the pack again and manually rebalance (this happened to somebody on here). I think he's in the "medium imbalance" regime where it still works with just some range quirks. Should fix itself over time with more driving.
 

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I've been having the opposite issue. I have mine set to charge to 80%, and when I start driving after a fresh charge, the charge level will increase to 81% or 82%. I'm not too too worried about it for now, but I am keeping an eye on it, as it seems to be getting larger. The first few charges stayed at 80%, the next few went to 81%, and the last couple have gone to 82%.
 
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dliunatic

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Looks like maybe it's balancing on it's own slowly. Today it only dropped from 90% to 87% in the first few seconds rather than down to 86%. ?

Here's a video of it in action, along with some PAAK normalness.



I actually brought it in yesterday to AutoNation Ford Frisco dealership to see if they could check out what the issue is, but turns out it'd be at least a couple days just to check it, and apparently they've sold all their loaners and Enterprise has no loaners so I'd be stranded without a car until they get to it. Guess I'll keep hoping this doesn't become a bigger issue for now...
 

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My FE has done this for many months - drops from 90% to 87% almost immediately. I told myself if it got worse (eg, drops to 85%) I’ll take it in. It has neither got worse nor improved for the last 90 days.
 

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After it is charged, I would charge to 100 percent on 120 volts Overnight. Then see what it does.
 

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Sigh... More battery wonkiness from me. So not sure if anyone else is experiencing this or if it's a residual issue from my HV battery replacement from a couple months back. I've noticed recently that when I charge to 90% through my preferred charge settings schedule, it will charge up to 90% and say that charging is complete, but then when I start the car I can literally see that percentage dropping within seconds by several percentage points. With past charges after the battery replacement, I've seen it go from 90% to 80%. I thought I was going crazy or had some weird schedule set, but today it went from 90% to 86% within the first minute of me unplugging the charging cable and starting my MME without even driving. Before the battery replacement, I never saw this weird percentage dropping issue...

I have tried removing the schedule and resetting it, which seemed to decrease the amount of percentage drop a bit. Tried charging up to 90% again immediately after the drop today and it added an additional 2kW or supposed 3% in another 19 minutes.

Also the odd part is if I charge to 100% I don't notice any weird battery percentage drops.

Anyone else having this issue and did you have HV battery replacements as well? Wondering if there's some battery reset that I need to do or recalibrate?
I just noticed the exact same issue today. Pulled it off the charger, SOC was at 90%. Backed the car out and drove to the stop sign about 100 feet away, then noticed my SOC now shows 85%. Usually I'll get a 1% drop right after taking it off the charge, but 5% seems pretty excessive. It was around 47 degrees outside, and probably 60 degrees in the garage where my car was parked. Climate control was set to auto at 74 degrees, e-heat was also turned on. I commute about 30 miles each way to work 4 days a week, so the car gets used regularly since I got it in March/April. I just broke 9k miles today (original battery).

This is the first time I've noticed such an extreme drop in SOC like that so I'll have to keep an eye on it. Just wanted to follow up that you're not alone with this issue.

@Ford Motor Company is this unusual behavior for the SOC to drop so quickly after being removed from the charger?
 

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I actually had the opposite happen over the weekend.

My car had charged to 90% overnight. I got in the car and it showed 90%. As I was leaving my neighborhood, I looked down and suddenly the car was reporting 92% SoC. And I know I didn't regen 2% of battery driving in the neighborhood.
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