Battery Percentage Dropping at Random

[ctuan13]

(TL;DR is at bottom for those who don't want the full story.)

So if you guys didn't already know about my deep discharge incident, you can see my previous post about that, but long story short, after that, my module voltage variance and SOC variance were much higher than they'd ever been before.

Well this was concerning as voltage variation between modules and certainly between cells could be an indication of the dreaded battery recall issue.

But over time since the incident almost three weeks ago, the voltage variance has crept downward and so has the SOC variance. Until today.

Today I finally made it to my friend's place in Washington state. I originally planned on charging up, but decided to get there, unhitch the trailer and then come back to charge.

I arrived with around 40%.

I was there talking with my friend and his wife for about an hour and a half. When I got back in the truck, the range estimate looked surprisingly low, considering I had arrived with near 40% and had unhitched the trailer. When I toggled to the just 25%, that didn't seem right.

But I figured, better get over to the charger, which is just three and a half miles from their house. As I'm driving, it seems that the percentage is dropping much faster than normal. I arrive with 20%.

The first EA dispenser I tried doesn't work so I go to move and switch to another. I look down, the battery percentage is now 17%. I'm rushing now, hoping I can get plugged in before it completely dies. I finally get it plugged into a working charger and the battery SOC reads just 14%.

Has anyone else seen this sort of behavior? Do you think this could have anything to do with the fact that the truck has been "running" almost my entire trip in order to keep two freezers on in the bed? I switch off the climate and lights when it's parked, but the truck is on.

TL;DR: After a deep discharge incident, module SOC variance and voltage variance were much higher than before, but seemed to slowly be returning to normal. Today my battery percentage dropped from 40% to 25% just sitting for an hour, then 25 to 14% just driving 3 miles. Anyone else experience this? Any advice?

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[Grumpy2]

https://www.f150lightningforum.com/...-left-me-stranded-6-miles-from-charger.19550/

 

[Adventureboy]

I suppose it depends on your freezers, but I would expect it to have very little impact unless it was extremely hot out. I ran two refrigerators, a freezer, a 49" TV, my computer, Internet and made coffee and lunch on a toaster oven for 8 hours and it only used 3% on my ER, so your rate of drop does not seem typical.

 

[Grumpy2]

You have been on this long road trip. It seems others who have had sudden drops in indicated battery level had ran the battery below 10% previously (perhaps recently?). Is that your experience too? Have you ran the battery down, say below 10% charge level in the prior few days?

How about on the top end of the charge level, did you notice the charge level staying at a high level for longer than expected?

 

[Zprime29]

IT 101 - If it isn't working right, reboot.

Never seen anything like that. I would try turning the truck off and let it settle for a bit too see of that purges the gremlins. I don't have strong confidence in that, but can't think of anything else to try.

 

[ctuan13]

UPDATE: So I posted originally while still at the charging station. But I didn't have time after getting back to their place to give you guys additional info. On the drive home regen was clearly limited and I could feel the service brakes kicking on to the majority of the deceleration. It was then I was reminded of another time the SOC and battery gauge seemed to go completely wild and it was only a couple months into my ownership of the truck.

When it happened that time it was shortly after I got the bug where the Lightning in the old UI glitched and became a Mach-E. Then maybe 20 minutes later I began noticing my range number just dropping alarmingly fast along with my power available. (I was driving down the highway at maybe 60 and it was probably 60°F).

So feeling something was definitely wrong, pulled over at a rest stop, shut off the truck, waited a minute and then disconnected the 12V battery and waited five minutes before reconnecting. Upon reconnecting, the Mach-E glitch was gone and so was the erroneous SOC and range numbers.

Well fast forward back to yesterday, I realized that maybe all of this could be traced down to a system glitch just like before. In addition, having installed a quick disconnect on my negative battery terminal, it's a piece of cake for me to disconnect my battery to do a 12V reset. So when I got back to their place that's what I did. I waited 10 minutes and reconnected.

I immediately jumped into CarScanner to check things out.
These are the first things I noticed:
- module variance was now at just 1.03% (was at 5.79% during incident)
- module voltage variance was about the same at 0.02V
- The SOC display was at 89 while the SOC was at 77.5

Over the next ten minutes I watched somewhat worriedly as the displayed SOC dropped slowly, while the truck just sat there "idling". But then it just stabilized around 81%. This correlates perfectly with the actual SOC of 77.5ish percent as there's always a slight intential discrepancy with Ford's programming between displayed and actual SOC. This delta at that displayed SOC is exactly what I tracked in the past when my truck was operating normally.

It was too late for a test drive last night, but I'm going to take the truck out later today and I'll let you know if everything is back to normal!

 

[ctuan13]

Update 2: So I went on a short test drive with my buddy and his daughter to a local supermarket. At first it seemed like things were back to normal. The SOC seemed to be reading normally and regen was working better.

But by the time I was halfway there I noticed it still wasn't regenning properly. At best I was only getting about half the expected regen and even when giving significant brake application, the regen was only coming in about 50%.

So when I got back to their place I was gonna throw my XTool scanner on the truck and see what I got. But we got busy with working on his yard and dinner so that didn't end up happening.

Finally got to do it an hour ago and there were lots of codes, but importantly, nothing major. Most had to do with either some sort of power interruption or momentary error. Many were likely caused by the 12V disconnect and some may have been caused by the deep discharge of the HV battery.

The only other codes were the four silent codes my truck always reports because it's salty that I have the TCU disconnected

I saved the code report for future reference and cleared all the codes.

I also scrolled through all BECM live data and saw no anomalous readings.

Module SOC variance and voltage variance continues to improve.

Haven't had a chance to test drive it yet, but will update again when I do to see if everything is resolved!

 

[MM in SouthTX]

https://www.f150lightningforum.com/...-left-me-stranded-6-miles-from-charger.19550/

How many of us are there? https://www.f150lightningforum.com/forum/threads/truck-died-5-miles-from-home.19715/

 

[BennyTheBeaver]

- The SOC display was at 89 while the SOC was at 77.5

The battery charge we have access to is 131 kW. The actual pack size is roughly 143 kW (roughly 9% difference).

I'm unfamiliar with how Carscanner reports. If Carscanner reports % of total capacity, instead of % of usable battery, that could explain most of the gap.

 

[Grumpy2]

Update 2: So I went on a short test drive with my buddy and his daughter to a local supermarket. At first it seemed like things were back to normal.

Waiting for Update 3.... How many "normal" recharging sessions has it been since the "deep discharge event"? Does it appear the BMS is more accurately estimating the SOC?

 

[GoodSam]

noticed it still wasn't regenning properly. At best I was only getting about half the expected regen and even when giving significant brake application, the regen was only coming in about 50%.

How do you determine that the Regen was not right? Viewing the green regen on the power meter? I have not noted the regen amounts while driving and braking often enough to make that judgement.
Also, what are these CarScanner values:
HVB SOC (High Voltage Battery State of Charge) Module Variation % and HVB Voltage Module Variation V, but are these showing the variation between the 6 or 9 battery modules or is this actually information from the individual cells inside the modules (I thought)?
Great that your 24 month HVB State of Health still shows 100% @MickeyAO !

 

[ctuan13]

Update 3:
Sorry for the delay, guys! My friends have several kids, so between helping them take care of some household projects and care for their numerous farm animals and entertaining their kids, I actually haven't had too many opportunities to leave their property! But I finally have had the chance for a couple test runs since the last update and here's what I've found:

After another test run it appears re-gen is now functioning properly.

So to those asking how I determined there was an issue, yes the green charging graphic was first indicator, but once I left the local dirt roads and got into faster traffic, the lack of regen when coasting and braking became obvious. Once I checked the charging input via CarScanner it was obvious something was wrong.

I never pinned down exact figures that were normal, but I've looked at CarScanner enough to know what is normal and what isn't. I was noticing about half of what was expected when coasting and when applying the brake (blended brakinf) the regen meter wouldn't go up past a quarter and the actual charge rate was probably 25% of what it should be maxed out.

After this run, I also noticed that the SOC and displayed SOC is holding steady and their ratio once again matches the healthy curve they normally do from the factory.

In addition, the module SOC variation continues to drop as does Voltage Variation.

As for the number of charges since the deep discharge event, it's hard to say as I'm on a cross country road trip so there's been a lot of DC fast charging. But since I did the 12V reset, there's been no AC charging as my friends don't have a 240V outlet. But I have done one short DC charging session from 70% to 85%.

I'll leave a screenshot of my CarScanner data below, but let's just say I'm happy with what I'm seeing and I'm cautiously optimistic that it's not a serious BMS or module issue. Believe me, I know that deep discharge definitely still did some damage, however minor. But I'm hoping that the fact that my battery has been otherwise babied its entire life, means that in the grand scheme of things, it's a wash.

Feel free to reply with any questions!

 

[FloridaMan655321]

Fantastic usage of the TLDR note on the top of the post. Haven't seen a properly placed TLDR in months.

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