Thinking on completely draining the HV Battery Pack. Thoughts?

[djwildstar]

Why would you restate the procedure, making edits, instead of just posting it exactly?

Because it was already linked above, so no need to copy-and-paste. The summary of the procedure was to give the reader a sense of what might be involved, so they could decide if they wanted to follow the link and read the detail (or not).

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[RickLightning]

Guess I'm less worried about BMS calibration and more about battery longevity. The BMS with its percentages and estimated miles is never accurate anyway as it depends upon what happens on the next drive.

When I first bot it just over 3 months ago I drove it over 200 miles home starting at 100% and used a 120v charger for a while. First trip to nearby town to get to a big charger had me limping into town on the back roads at 35 mph at 1% then probably right at 0% sweating bullets on a busy street hoping it don't shut down as I pulled up to the charging station. My Extended battery with 131 kwh useable and 144 kwh actual still had its reserve capacity in it. Looking back at the charge ticket, it took 135.144 KWH in 2h 49min to get back to 100%. So apparently I ran it down the very first time.

Now with winter here, I plug it and charge it to 100% whether I drove 30 miles or 60 or 150. I'm afraid to go to 80 or 90% because I may wakeup and need to drive somewhere and the wife or I don't want to have to worry about being stuck out in the Kansas boondocks. Don't need that extra anxiety at our old age. So I'll just deal with it for now and maybe in the spring I can not have to plug in every night.

That bolded statement has nothing to do with the energy in the pack, because it uses some energy to balance the cells. When I charge to 100%, I find that I use around 10% more energy to cell balance. In other words, if I'm at 90% and going to 100%, it should take 13kwh. Yet it might take 23.

 

[21st Century Truck]

How about just resetting the BMS? To wit:

1. Shut truck down and open door for 20+ seconds.
2. Turn truck on to only Accessory mode (blinking green light on push button).
3. Wait at least 10 seconds.
4. Flash the high beam 5 times, quickly.
5. Step on brake pedal 3 times, quickly.
6. Wait 10+ seconds, watching the red solid battery icon on the IPC.
...the red battery icon will flash several times, and then the BMS is reset.

This can't hurt and might help. Some experienced members here do this every six months.

 

[Timeless Epoch]

How about just resetting the BMS? To wit:

1. Shut truck down and open door for 20+ seconds.
2. Turn truck on to only Accessory mode (blinking green light on push button).
3. Wait at least 10 seconds.
4. Flash the high beam 5 times, quickly.
5. Step on brake pedal 3 times, quickly.
6. Wait 10+ seconds, watching the red solid battery icon on the IPC.
...the red battery icon will flash several times, and then the BMS is reset.

This can't hurt and might help. Some experienced members here do this every six months.

Me resetting the BMS.

 

[TaxmanHog]

How about just resetting the BMS? To wit:

1. Shut truck down and open door for 20+ seconds.
2. Turn truck on to only Accessory mode (blinking green light on push button).
3. Wait at least 10 seconds.
4. Flash the high beam 5 times, quickly.
5. Step on brake pedal 3 times, quickly.
6. Wait 10+ seconds, watching the red solid battery icon on the IPC.
...the red battery icon will flash several times, and then the BMS is reset.

This can't hurt and might help. Some experienced members here do this every six months.

This procedure is for the 12v battery BMS, not the HVB BMS!!

 

[21st Century Truck]

This procedure is for the 12v battery BMS, not the HVB BMS!!

Of course.

 

[chl]

This also would apply to the Lightning…
https://www.macheforum.com/site/threads/hv-battery-calibration-procedure.23815/

We do not have LFP's so that procedure is not required or recommended.

And for our NCM batteries, deep discharges of the HV battery are a significant factor is reduced capacity and longevity accord to studies of these things.

So I would not advise going down to 5%.

Yes there is a buffer at both the upper and lower ends, but the deeper the discharge, the greater the ill effect on longevity.

 

[chl]

Deep discharges of the HV battery are a significant factor is reduced capacity and longevity accord to studies of these things.

So I would say don't do it. Just regular charging and discharging and use should keep the battery cells closely balanced.

The BMS for the HVB balances the cells/modules during charging over time, but because of the battery size, it can take a lot of time.

For example, when they replace a battery module in the Lightning, they say it can take as long as 22 days for the modules to get into balance.

No Regular 100% Charging Needed: Unlike some other EVs with passive balancing or with LFPs, the F-150 Lightning's NMC (N=Nickel, M=Manganese, C=Cobalt) battery technology does not require regular charging to 100% for calibration purposes.

From what I have read, the Lightning uses active cell balancing, meaning during charging the BMS is actively balancing the cells so no special charging procedure is needed.

Some EVs may require periodic charging to 90 or 100 percent in order to balance the cells, but that is because they use passive balancing and/or have LFP battery technology.

Ford says in Ford literature:

The BMS continuously optimizes charging behavior:
Adjusts charging rates based on battery temperature, state of charge, and
cell health
Implements cell balancing during charging to ensure uniform wear
Varies maximum charge levels based on driving patterns and needs
Adapts fast-charging profiles to minimize degradation

So it also keeps track of your driving patterns and needs and adjusts the maximum charging levels based on that.

"The F-150 Lightning features the most advanced Ford Battery Management
System (BMS) to date, incorporating artificial intelligence and predictive
analytics."

"For frequent short-trip users, the system may limit maximum charge to
80-90% to extend battery life, while automatically enabling 100% charges
before planned long journeys."

From the 2025 Ford F-150 Lightning: Battery Options for Performance

 

[chl]

FYI:

Research by Guena and Leblanc shows a “four-fold improvement is expected between 100% DOD and 50% DOD" meaning that a battery that is only cycled between 80% and 30% will hold its capacity four times as long as the expected life of a battery cycled from 100% to 0% -- although, in the real world, lithium ion batteries in cars never reach really 100% or 0%. See the note above on usable capacity vs. total capacity....

Battery University is a free resource that collects and shares cutting edge battery science. They provided the data for the table below, which shows how many cycles it takes for different batteries to lose 20% of their original capacity, based on the depth of discharge. A battery that uses 40% of its depth of discharge lasts 2.5 times longer than one that uses 80%. This table has data for one popular EV battery chemistry. ...

https://www.recurrentauto.com/resea... it Matters.,to 95% or discharged down to 12%.

 

[mr.Magoo]

A battery that uses 40% of its depth of discharge lasts 2.5 times longer than one that uses 80%. This table has data for one popular EV battery chemistry. ...

https://www.recurrentauto.com/research/one-simple-trick#:~:text=The Science - and Why it Matters.,to 95% or discharged down to 12%.

Please don't take this personally (as you're only referring to what's said in the reports).

While the general conclusion still stands (that it's better to have smaller / lower ammounts of discharge) the "facts" and the effects are a bit of an apples vs. oranges comparison here considering that they're talking about charge cycles and not throughput.
I mean, if you use 40% instead of 80% you'll charge twice as often, so in reality your battery will not last 2.5 times "longer".

It is also not an apples to apples comparison in that they charge the battery / cell to 100% in the 80% discharge cycle vs. say 30-70% in the 40% cycle and we know that charging to 100% is "bad" so how much of that loss is due to charging to a high SoC and how much is due to the depth of discharge ?
No-one changes their charge levels based on their anticipated use the next day or two, we all charge to 70-80-90% or whatever our default setting happens to be, so it would be more interesting to see a 80%-20% vs. 80%-40% vs. 80%-60% and then take overall throughput in mind. Is charging (i.e. ABC) 65%-80% every day better than 35%-80% every three days. Now add to that equation the effects of the battery sitting at higher SoC levels for more / longer time...

I suppose my point is that I don't think synthetic / lab tests tells the whole truth about charging behaviours and the longevity of our batteries, doing real life use-case tests would take years vs. weeks / months for the synthetic ones and I'm not aware of anyone that's actually spent that time (and money) to get those kind of results.

In the end I find this quite interesting, but I'm definitely not losing sleep over it.
I don't follow ABC (not so much by choice as by convenience), instead I charge when I need to, usually around 20-40% SoC and I charge to 80%, either way I'm pretty sure the truck will outlive me.

As a sidenote, have anyone in the EV world encountered a "battery diagnostics test" as a part of the tradein / appraisal process ? I mean, if you have a curb rash on your wheel you get money taken off your trade, but if the thing lived on a L3 charger to 100% all its life v.s. pampered / ABC L2 60-80% preconditioned, etc. But I suppose no-one cares about that kind of "invisible" wear/tear.

 

[PJnc284]

We do not have LFP's so that procedure is not required or recommended.

And for our NCM batteries, deep discharges of the HV battery are a significant factor is reduced capacity and longevity accord to studies of these things.

So I would not advise going down to 5%.

Yes there is a buffer at both the upper and lower ends, but the deeper the discharge, the greater the ill effect on longevity.

It's interesting that one of the few if not the only one here that had direct experience testing the cells said he didn't let his truck go below 20%. Believe he didn't like something with the resistance. He left us for a Hyundai or Kia a while back though.

 

[Zprime29]

It's interesting that one of the few if not the only one here that had direct experience testing the cells said he didn't let his truck go below 20%. Believe he didn't like something with the resistance. He left us for a Hyundai or Kia a while back though.

If I recall, after he tested the batteries the summary was don't go under 20% SOC, keep depth of discharge as small as possible, and don't let it get too hot. I abide by the first two but it's hard to manage the third one in the desert. The parking lot bakes it to over 120F every summer. I attribute that as the biggest reason for my battery's ~3% loss of capacity over 3.5 years. In the grand scheme, that ain't too bad.

 

[bc1]

That bolded statement has nothing to do with the energy in the pack, because it uses some energy to balance the cells. When I charge to 100%, I find that I use around 10% more energy to cell balance. In other words, if I'm at 90% and going to 100%, it should take 13kwh. Yet it might take 23.

Got it. Didn't know about 10% to cell balance. Then add some kwh to run the battery heater/cooler and whatever else such as lights and charge the 12v battery. Since I'm plugging in every night to 100% I will see how many kwh per mile I get compared to what the trip meter says it uses.

On the other hand, after reading about this battery calibration procedure, if the goal is to get a better prediction of available miles on the left side of the speedometer panel, then forget it as it will never be accurate for the variation in roads that I may drive on any particular day, either state highway or interstate, etc. The percentage is never accurate either so that side of the panel is nothing more than a general guestimate/guideline and about as useful as the gas gauge on a regular vehicle that is stuck on full for a hundred miles or you are somewhere between a quarter and an empty tank and you don't really know how many gallons are left when on empty.

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