Elevated HVB Module Variation - What's yours? (Solved post 26)

[bmwhitetx]

While you are charging, open the app and verify it is actively charging at a stable rate.

Use the app to slide to 100%, it will specifically ask you "this charge session only"?

This is how I charge to 100% once a month, it always works for me.

Yep, I did those steps. I think there is a software issue. The app showed 100% as the destination and I got a notification that the truck had charged to 100%. But when I started the truck, it was at 82.

Here is the SOC as reported by FordPass:

Started charging at 4:05, EVSE reported 6.9 kW rate. Around 7:30 when SOC=80%, the charge rate dropped to around 1 kW. At 9:00 it reported the truck was charged to 100%. EVSE reported 0.0 kW charge rate. I went out and turned the truck on at 10:00pm and it immediately corrected to 83% and began "charging" again. This morning started the truck around 10:00am and it dropped once again to around 83.

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[GoodSam]

Tried to charge to 100% last night and the app says it went to 100% but when I start the truck, the SOC dropped to 84. I think this is just an error with the fact I have my home set as a charge location with 85%. I moved the override slider to 100% but I think it's not taking. I believe others have reported this with the most recent OTA. The app also way over reported the amount of kWh ingested - no where close to what my EVSE reported it saw.

See this December 2024 note that Ford put out:
https://www.f150lightningforum.com/...able-to-reach-target-charge.23075/post-447399
This is SSM 53208 special service message
https://static.nhtsa.gov/odi/tsbs/2024/MC-11011811-0001.pdf?utm_source=perplexity

Based on others with same problem, I would guess a bad cell in a HV battery module / array.

 

[bmwhitetx]

See this December 2024 note that Ford put out:
https://www.f150lightningforum.com/...able-to-reach-target-charge.23075/post-447399
This is SSM 53208 special service message
https://static.nhtsa.gov/odi/tsbs/2024/MC-11011811-0001.pdf?utm_source=perplexity

Based on others with same problem, I would guess a bad cell in a HV battery module / array.

Thank you!!! This is exactly what I am experiencing. I will try one more time tonight since I have deleted charging locations which a dealer may think is the issue.

 

[Firn]

So, your graph of SoH means nothing without noting the reference to previous charging details and SoC.

For instance, if you charge to 90% each night on a L2 at home, then you'd take the SoH measurement @90% SoC after each charge i.e. each morning before you leave. Your driving habits are certainly rare compared to 90%+ of people charge their EV every night.

The Lightning BMS does passive balancing only, and will only balance at the top end of a charge once the first cell reaches maximum SoC. Basically resistors are switched on to waste the charge power as cells reach maximum SoC, in this way all cells can be raised to the same maximum level (balancing).

So, if you have 8% variation and you don't charge past 92% SoC then you haven't balanced anything. This is why you should charge to 100% occasionally, to fully balance everything. Yes, I do fully believe FMC has relaxed the threshold of detection of bad modules to ease the pain of module replacements, but will they ever disclose this: NO. Just like they will not disclose any of the BMS algorithms for balancing, power limiting, or pre-conditioning. They only view disclosure of tech details as increasing their liability. I have tested this after 2 module replacements, one at 50kmi and one at 90kmi. I now have 140kmi, I charge every night to 90%, if I go over a month without charging to 100% I have seen over 6% module variation, soon as I charge to 100% it's back down to less than 0.2%. It's the rate at which the cells become unbalanced that is a problem. If you charge to 100% and get to less than 1% variation, then drive one battery and get more than a few % that's a problem. If you get 6% in a month charging to 90% or less, that's not a problem.

Where is it confirmed the battery only does balancing with external power?

Based upon my logger I see reduced module variation as rest time gets long.

https://www.f150lightningforum.com/...ency-via-custom-pid-logging.34523/post-641705

 

[ZSC100]

Where is it confirmed the battery only does balancing with external power?

Based upon my logger I see reduced module variation as rest time gets long.

https://www.f150lightningforum.com/...ency-via-custom-pid-logging.34523/post-641705

Love your work with the logging. I hadn't noticed you did that graph, but after looking at it now I suspect it's just a noise/fidelity issue as you're looking at mV change and we're only talking about +/- 10mV changing thermals from when the vehicle turns off to when it turns on the next time are probably causing the scatter in the plot. It's also what causes people to think their truck is malfunctioning when they see miles of difference in range from when they turn off to when they turn on and/or when the temp changes while driving for whatever other reason. In Oklahoma it's common to get in your vehicle for a 1hr drive then when you step out it's 50+degF cooler or hotter. The battery has zero insulation, so when air is rushing over that aluminum pack case it can really influence the pack temp.

My personal confirmation of passive only balancing is from basic analysis of the BMS Module inside the battery pack and evidence of what I've seen with watching the data from my truck. I've seen 6%+ before that was reset in one night to 0.2% after charging to 100, but otherwise charging to 90 every night.

See how small the module is (thin PCB inside) and how small the balancing wires are to each module. These two facts mean that it's only passive balancing and those wires can't handle more than 5A continuous by design? So, this is why it takes a LONG time to balance the battery at the top. Active balancing requires capacitors and a much more complicated BMS power electronics. Also, Balancing always results in a net loss of energy over the pack, more so with passive balancing so it wouldn't make sense to EVER balance an EV if not charging b/c the vehicle has no way of knowing your future plans, You might need every mile of range to reach your destination.

 

[bmwhitetx]

Well, looks like it's off to the dealer. Did another attempt at 100% charging last night and same result. Once it got to 80% SOC, charging slowed significantly and when it got to 82%, charging stopped and the SOC jumped to 100%. Starting the truck this morning, the truck showed 100% when I got in but as soon as I pressed Start it went to 82%. Same as others have experienced (one example).

SOC:

Charge kW

 

[The Weatherman]

Well, looks like it's off to the dealer. Did another attempt at 100% charging last night and same result. Once it got to 80% SOC, charging slowed significantly and when it got to 82%, charging stopped and the SOC jumped to 100%. Starting the truck this morning, the truck showed 100% when I got in but as soon as I pressed Start it went to 82%. Same as others have experienced (one example).

SOC:

Charge kW

Yep that should be your plan.

This behavior has, as far as I recall, always been a symptom of of a failed battery cell.

 

[digitaldad]

Well, looks like it's off to the dealer.

Sorry for the news!

 

[chriserx]

Well, looks like it's off to the dealer. Did another attempt at 100% charging last night and same result. Once it got to 80% SOC, charging slowed significantly and when it got to 82%, charging stopped and the SOC jumped to 100%. Starting the truck this morning, the truck showed 100% when I got in but as soon as I pressed Start it went to 82%. Same as others have experienced (one example).

SOC:

Charge kW

If you don't/can't immediately drop it off try a slower charge rate if you can, seems to be about 40A already but can't hurt...probably.

 

[bmwhitetx]

If you don't/can't immediately drop it off try a slower charge rate if you can, seems to be about 40A already but can't hurt...probably.

I thought the same thing. I tried 40A two nights ago and 32A last night. Same result .
Waiting for dealer callback.

 

[bmwhitetx]

Update. Contacted dealer yesterday and they said they could get to it today so I dropped it off last night. I made sure the Advisor knew about the SSM and gave him a copy (thanks @GoodSam!). He said he had a knowledgeable EV tech that would handle.

Got a text this morning that a battery module is bad, covered on warranty (duh) and is normally $7500. No ETA on when part will arrive. Says Ford will cover a loaner.

Being curious I bought a 3-day PTS subscription. Shows tech connected to FDRS and immediately did a Battery Health test. Then spent the next hour reviewing the Workshop manual.

Battery Health test shows cell 29 in module 3 well below average:

My last Car Scanner look was showing a 0.130 V variation from average which looks to be pretty close to the numbers above.

So I join the "two module failures" club. First one was almost exactly 2 years ago. Module 6.

 

[ZSC100]

Update. Contacted dealer yesterday and they said they could get to it today so I dropped it off last night. I made sure the Advisor knew about the SSM and gave him a copy (thanks @GoodSam!). He said he had a knowledgeable EV tech that would handle.

Got a text this morning that a battery module is bad, covered on warranty (duh) and is normally $7500. No ETA on when part will arrive. Says Ford will cover a loaner.

Being curious I bought a 3-day PTS subscription. Shows tech connected to FDRS and immediately did a Battery Health test. Then spent the next hour reviewing the Workshop manual.

Battery Health test shows cell 29 in module 3 well below average:
View attachment 112827
My last Car Scanner look was showing a 0.130 V variation from average which looks to be pretty close to the numbers above.

So I join the "two module failures" club. First one was almost exactly 2 years ago. Module 6.

Ford has disgustingly under advertised the module failure rate, I think it's close to 10%, but they believe if they keep it advertised/believed under 4% they can avoid liability (god knows they need it). If they would've handled it correctly like so many other things they shouldn've done it honestly would be no big deal. A competent tech can replace a module in just 2hrs. But that requires that they have one on the shelf. I've said it for 3yrs+ now, Ford should have an ER and SR standard module sitting on the shelf at every eCertified dealer in the nation,, that's only about 3000 of each. It would have saved them WAY more in black eye value than the cost.

When my first module failed here in small town Tulsa, OK, in 2023 with 50kmi, my dealer had already performed over 50 lightning module replacements. When my 2nd module failed at 90kmi they had done over 100. And every one of my friends in Tulsa with Lightnings have had 1 or 2 modules fail. It's crazy that ford is letting people's trucks sit at dealers for weeks for a 2hr job because they are too stupid and cheap to do the right thing.

 

[ZSC100]

Update. Contacted dealer yesterday and they said they could get to it today so I dropped it off last night. I made sure the Advisor knew about the SSM and gave him a copy (thanks @GoodSam!). He said he had a knowledgeable EV tech that would handle.

Got a text this morning that a battery module is bad, covered on warranty (duh) and is normally $7500. No ETA on when part will arrive. Says Ford will cover a loaner.

Being curious I bought a 3-day PTS subscription. Shows tech connected to FDRS and immediately did a Battery Health test. Then spent the next hour reviewing the Workshop manual.

Battery Health test shows cell 29 in module 3 well below average:

My last Car Scanner look was showing a 0.130 V variation from average which looks to be pretty close to the numbers above.

So I join the "two module failures" club. First one was almost exactly 2 years ago. Module 6.

This tracks with what you were experiencing, NMC Li usable range is 3.0-4.2V,, 0.13V variation is 11%, so you not being able to charge past 85% makes sense, the BMS couldn't hold back 95 cells while trying to pump up cell 29.

 

[TaxmanHog]

And yet, here I am and many others with ZERO module failures, 10% is not likely real since we don't know for sure how many other success stories are out there.

The failure reports tend to find forums to gather more information regarding their negative experience and share with likewise affected owners.

 

[PJnc284]

It's crazy that ford is letting people's trucks sit at dealers for weeks for a 2hr job because they are too stupid and cheap to do the right thing.

Could be worse I guess. Ram has 1000's of Etorque generators on backorder with some taking 2 months plus. Took them about 5 weeks to get mine in.

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