New issue happening, soc % dropping upon departure, anyone else have this?

[Maxx]

This is definitely new for me. It either must have been in the last software update (in my signature) or there was an unpublished update.

I just took a trip. Charged to 60% two hours before the trip. Immediately after leaving driveway, I was at 58%. Looking at OBD2 and energy. Efficiency calculation was accurate assuming that 2% never existed.

Battery temp remained the same during trip but what was surprising is that no energy went to exterior temp being in 90s F.

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[Maxx]

This is definitely new for me. It either must have been in the last software update (in my signature) or there was an unpublished update.

I just took a trip. Charged to 60% two hours before the trip. Immediately after leaving driveway, I was at 58%. Looking at OBD2 and energy. Efficiency calculation was accurate assuming that 2% never existed.

Battery temp remained the same during trip but what was surprising is that no energy went to exterior temp being in 90s F.

This is from my return trip. I took a shorter slower route. Look at energy and SOC. The truck was parked from 1PM to 4PM. SOC displayed remained the same at 48.5 but energy went up from 44.31 Kwh to 45.78 Kwh while it was parked. Then in 3 minutes energy dropped but SOC went UP by 0.5%. as screwed up as this sound, the upshot is for this trip I got some energy show for exterior temp.

If you have any theories on what the truck is thinking please do share.

p.s. I did not record the energy when initial charging to 60% was done to see if that 2% loss shows in terms of energy as well or it is just SOC calculation. If any of you do that, please share.

 

[CyclopsThere]

My theory is that the soc displayed to us is a calculation rather than a true current state. There is no way that 1-2 kWh discharges from our battery packs in such a short time, so to me that means it must be the result of a calculation that is slicing time either too rapidly or not enough, and "looks ahead" based on current drain prior to giving us "current SOC"

If you have myview up with mi/kWh you can see similar result of too-often slices of data being displayed to us-- within the first couple of miles you can have ridiculous numbers before over time evening out to "the usual"

 

[On the Road with Ralph]

Preface: I am not being snarky, just making a science-based comment:

Nearly all EV drivers tend to think of their batteries like gas tanks; they imagine that they "hold" a certain measurable quantity of electrons that get drained to power the motors. The reality is FAR more complicated than that.

Lithium ion batteries are, in essence, quantum devices. Their storage and discharge of electricity is not subject to direct physical measurement. State of Charge (SoC) is not a sampling of some quantitative characteristic of the battery because no such measure exists. Quite literally, as a quantum device, a lithium ion battery's actual capacity is unknowable. We can infer it from other measurements such as voltage, which at best is a poor proxy for SoC.

So, hand-wringing over a couple percent of SoC after charging is a fruitless exercise. The battery management system (BMS) in your Lightning is doing the best job it can, using a given set of inputs run through an algorithm or two, to estimate the current level of charge. But a host of variables will impact the displayed SoC - just as they do the estimated range in the GOM.

Maybe one day SoC will be determined with greater precision, but in the present, just don't sweat a couple of percent.

 

[Grumpy2]

Quite literally, as a quantum device, a lithium ion battery's actual capacity is unknowable.

With a known SOC the estimate of our range by the BMS at any time will depend on the factors we discuss about low range (speed, temperature, hard driving...) There are two methods to determine our SOC. voltage and coulomb counting (monitoring the amperage flow in and out of the battery). About 95% of our available energy between "full" and "empty" is only about 1.5 volts of the individual cells, so very little difference in voltage is significant to SOC. We have a very flat cell charging curve that changes rapidly both near empty and full.
Coulomb counting is considered more accurate, however it to is effected by temperature, degradation, resistance, etc.
The big issue is establishing the current SOC before these measurement. Errors will accumulate. True voltage of the cells will only happen after they have rested for a period (voltage rebound = polarization). MickeyAO waits 24 hours during testing.
We can't consider the SOC and the GOM as accurate without realizing the standard of error that is involved and why it exists. On a long trip with continuous charging the errors could be significant. When a modual is replaced, Ford says to wait 22 days before getting the original accuracy.

 

[Grumpy2]

Here is a video involving Dr. Dahn that discusses how the accumulated errors that impacts the accuracy of SOC and thus GOM estimates can be eliminated with LFP batteries by taking them to 100% weekly to reestablish the SOC accurate readings without reducing battery life.

 

[Maxx]

I plan to do the following when I get the chance. If any of you get to do it first please share.

After the truck is parked for 4 hours at moderate temps at 30%, SOC, record, SOC displayed, battery temp, and energy. Charge to 70% SOC. Record how much energy the charger put out. And record SOC displayed, battery temp, and energy as soon as the charging is complete. Wait for at least 4 hours, measure again and drive monitoring the SOC and Energy every 30 seconds until SOC drops 2%.

I am hoping to find out if that 2% was lost, never made it to the battery to begin with or was miscalculated somewhere along the line. The words quantum or complicated does not make me any less curious.

 

[02Reaper]

I plan to do the following when I get the chance. If any of you get to do it first please share.

After the truck is parked for 4 hours at moderate temps at 30%, SOC, record, SOC displayed, battery temp, and energy. Charge to 70% SOC. Record how much energy the charger put out. And record SOC displayed, battery temp, and energy as soon as the charging is complete. Wait for at least 4 hours, measure again and drive monitoring the SOC and Energy every 30 seconds until SOC drops 2%.

I am hoping to find out if that 2% was lost, never made it to the battery to begin with or was miscalculated somewhere along the line. The words quantum or complicated does not make me any less curious.

I'm also curious as if any other companies producing EV's seem to have the issues we have with SOC display, Range estimates all over the place, and especial BCM calculation of the battery state of charge at low levels like people posting here of going dead at 4%, 7% or low states of charge. I'm sure ya'll watch the videos of the range tests and other tests online of stuff like this. Ford is the only one I see with issues like mentioned above and in threads here and elsewhere.

 

[Maxx]

I'm also curious as if any other companies producing EV's seem to have the issues we have with SOC display, Range estimates all over the place, and especial BCM calculation of the battery state of charge at low levels like people posting here of going dead at 4%, 7% or low states of charge. I'm sure ya'll watch the videos of the range tests and other tests online of stuff like this. Ford is the only one I see with issues like mentioned above and in threads here and elsewhere.

With older devices ( my electric shaver, tablets, ....) I have noticed bellow 10% and especially bellow 5%, SOC falls off the cliff rapidly, but I have never seen the 2% fast SOC drop at higher SOCs on anything else. I am sure by the time we figure this out an OTA update will fix this and will break something else. As long as my truck is running and is healthy, this type of booboos I am OK with but still curious what is going on. The thing I am worried about is that I have never seen my cooling system bring my battery temp down. But that is an issue for another thread. I am on vacation but I am hoping to check a few things on this and post after I am back.

 

[02Reaper]

With older devices ( my electric shaver, tablets, ....) I have noticed bellow 10% and especially bellow 5%, SOC falls off the cliff rapidly, but I have never seen the 2% fast SOC drop at higher SOCs on anything else. I am sure by the time we figure this out an OTA update will fix this and will break something else. As long as my truck is running and is healthy, this type of booboos I am OK with but still curious what is going on. The thing I am worried about is that I have never seen my cooling system bring my battery temp down. But that is an issue for another thread. I am on vacation but I am hoping to check a few things on this and post after I am back.

I've seen my cooling system bring the battery temp down with a charging stop programmed into the stock navigation. It was 108 degrees last summer going down the highway, so at least I have seen that work. Honestly though I think Ford lets the battery temperature get out of range before commanding cooling and the system has to play a lot of catch up to bring the temp within an acceptable range. Essentially its like going on vacation in the heat of the summer and turning your ac off the whole time you're gone instead of just turning it up several degrees.

 

[Skidrowe]

The immediate drop you see when starting it after a charge could be caused by a cell imbalance across different cells in the battery. It can limit the total output voltage of the battery which will result in a drop in the calculated SOC after beginning to draw from the battery. Assuming the BMS performs rigorous cell balancing after the battery reaches a high SOC, this issue can be resolved by charging your battery to 100% and leaving it on the charger beyond that state to allow the BMS to balance all the cells (it continues to draw at a low rate from the charger for this). If that doesn't resolve your issue, then it's possible that you have one or more cells that have degraded faster than the others making this a permanent phenomenon. Ford could test for that case.

As others above have indicated, measuring SOC is difficult at best and it is specific to the battery chemistry and build implementation. This is a good read to know why calculating SOC is hard and can possibly point you towards some variables that might be relevant in your testing. Just know that it'll be difficult to draw confident conclusions without knowing the algorithms implemented in Ford's BMS (likely comes from a 3rd party vendor). https://chargedevs.com/features/the-challenges-of-battery-state-of-charge-measurements/

 

[Maxx]

I've seen my cooling system bring the battery temp down with a charging stop programmed into the stock navigation. It was 108 degrees last summer going down the highway, so at least I have seen that work. Honestly though I think Ford lets the battery temperature get out of range before commanding cooling and the system has to play a lot of catch up to bring the temp within an acceptable range. Essentially its like going on vacation in the heat of the summer and turning your ac off the whole time you're gone instead of just turning it up several degrees.

Good to know. I keep the truck mostly in the shades. Sounds like mine may be working like yours, and I have never checked it with temps high enough. I just assumed since battery likes to work around body temp, with my inlet temp being in low 50s, Ford would let it flow through the battery and my battery that is in 80s will drop temp. I wish Ford had a video of how this is suppose to work with some animation of the whole system and where the threshold is ( when cooling kicks in).

The immediate drop you see when starting it after a charge could be caused by a cell imbalance across different cells in the battery. It can limit the total output voltage of the battery which will result in a drop in the calculated SOC after beginning to draw from the battery. Assuming the BMS performs rigorous cell balancing after the battery reaches a high SOC, this issue can be resolved by charging your battery to 100% and leaving it on the charger beyond that state to allow the BMS to balance all the cells (it continues to draw at a low rate from the charger for this). If that doesn't resolve your issue, then it's possible that you have one or more cells that have degraded faster than the others making this a permanent phenomenon. Ford could test for that case.

As others above have indicated, measuring SOC is difficult at best and it is specific to the battery chemistry and build implementation. This is a good read to know why calculating SOC is hard and can possibly point you towards some variables that might be relevant in your testing. Just know that it'll be difficult to draw confident conclusions without knowing the algorithms implemented in Ford's BMS (likely comes from a 3rd party vendor). https://chargedevs.com/features/the-challenges-of-battery-state-of-charge-measurements/

This very well could be the case for me. I have charged it to 100% only a few times in a year and a half. Last time was in early May. I usually float between 40-60 SOC (in Summer, 30-50). I suspect, this may fix my issue. I will report back after charging to 100%. Thanks.

 

[02Reaper]

I want to retouch on this thread and link some findings I saw last night. I noticed first hand using car scanner where the SOC was 1-3% less in some places vs the SOC Display. https://www.f150lightningforum.com/forum/threads/quick-drop-in-soc.21086/#post-415757

 

[Maxx]

I want to retouch on this thread and link some findings I saw last night. I noticed first hand using car scanner where the SOC was 1-3% less in some places vs the SOC Display. https://www.f150lightningforum.com/forum/threads/quick-drop-in-soc.21086/#post-415757

There are three SOC numbers that car scanner can show you. One of them is SOC Display which always matches what you see in the car. The other one is the real SOC which counts the top and bottom part of the battery that is not accessible to the driver. I believe you are comparing these two. I don’t remember what the third one was right now.

The issue on this thread is different; my displayed SOC drops 2% as soon as I move the truck sometimes only a few feet. This happens both in car scanner and on truck display.

 

[02Reaper]

There are three SOC numbers that car scanner can show you. One of them is SOC Display which always matches what you see in the car. The other one is the real SOC which counts the top and bottom part of the battery that is not accessible to the driver. I believe you are comparing these two. I don’t remember what the third one was right now.

The issue on this thread is different; my displayed SOC drops 2% as soon as I move the truck sometimes only a few feet. This happens both in car scanner and on truck display.

I didn't realize the issue in this thread was that it was dropping on both. I have the same issue with mine though. The truck will be charged to 85% and on the a/c charger overnight as soon as I unplug and turn the truck on before I even back out of the garage the display is saying 84% and before I get even a mile up the road it will be 83%.

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