For those of you worried about charging to 100%...

[OON7]

I've been charging to 95% at work and 80% at home for the last two months since free work charging became available for me. I can't say I have noticed any issue with my range nor do I expect to really ever notice any issues coming from charging up past the recommendation.

The only thing that is irritating me to no end is when magically all of my preferred charge settings get wiped after a powerup or FordPass update. It has happened to me twice in the last six months. I had about 10 saved places/rules (seven were just bad GPS coordinates for when I was charging at home and it thought I was somewhere else).

I got into my car at 100% charge today at home and I was just angry about using the electricity needlessly at home when I could have gotten the free electrons at work. Concern for battery health didn't even cross my mind, just the $2-3 bucks extra that will be on my next electricity bill LOL.

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[OON7]

I don't like to do 100% much for a 2nd reason too -- it sometimes disables regen braking if the battery is too full. Always catches me by surprise when it does that. Only happened a handful of times but it's annoying.

Not gonna lie, that scared the crap out of me the first time I experienced it. I almost rolled into an intersection not paying attention to "coasting" on unbridled at 100%.

 

[MachTee]

Dumb question. Since Ford has a ~10% buffer in the pack, will degradation eat into the buffer first, or will it affect actual usable capacity first?

@OON7 @dbsb3233 I've charged my car to 100% a few times. Rolling down the steep hill in my neighborhood, it had never decreased regen. I've always credited that to the 10% buffer.

 

[Richard L.]

When is charging to 100% not 100%? When your extended range battery has 10.8 kWh buffer. I’m not concerned and the EPA mileage advertised is based on a full charge. Who am I to dispute what the government tells me. ?

 

[OON7]

Dumb question. Since Ford has a ~10% buffer in the pack, will degradation eat into the buffer first, or will it affect actual usable capacity first?

@OON7 @dbsb3233 I've charged my car to 100% a few times. Rolling down the steep hill in my neighborhood, it had never decreased regen. I've always credited that to the 10% buffer.

No idea on part one, but my hope/assumption is the buffer first.

For the second part, whenever I get to 100% I've noticed it for the first couple of miles, it happened today too. It is like there is zero regen braking for me at the start of the drive when on unbridled at 100%.

 

[dbsb3233]

Dumb question. Since Ford has a ~10% buffer in the pack, will degradation eat into the buffer first, or will it affect actual usable capacity first?

@OON7 @dbsb3233 I've charged my car to 100% a few times. Rolling down the steep hill in my neighborhood, it had never decreased regen. I've always credited that to the 10% buffer.

Most of time charging to 100% hasn't cut off regen. I think I've had it happen 3 or 4 times out of maybe 50 100% charges. Not sure if not all 100%'s are the same (full vs really full), or weather matters, how long ago it hit 100% (and cooled down), or what.

 

[dbsb3233]

Dumb question. Since Ford has a ~10% buffer in the pack, will degradation eat into the buffer first, or will it affect actual usable capacity first?

Not sure anyone has really figured that out for sure yet. I think that's why someone was asking about an OBD2 reading earlier, to try to see the difference between the usable battery and the total battery (with buffers).

As you alluded to, it's possible any degradation comes out of the upper buffer first, which would mean we wouldn't notice any range difference until the degradation creeps down into the usable battery.

 

[ZuleMME]

Not sure anyone has really figured that out for sure yet. I think that's why someone was asking about an OBD2 reading earlier, to try to see the difference between the usable battery and the total battery (with buffers).

As you alluded to, it's possible any degradation comes out of the upper buffer first, which would mean we wouldn't notice any range difference until the degradation creeps down into the usable battery.

Pretty certain this is how is works because of the physics of charging. You charge to a voltage which maps to a percent. When the degradation happens it just can't continue to build voltage to get to the target. Of course I'm taking an educated guess here... But based on this it comes off the top buffer first. Years before you'll see it.

 

[SnBGC]

Dumb question. Since Ford has a ~10% buffer in the pack, will degradation eat into the buffer first, or will it affect actual usable capacity first?

@OON7 @dbsb3233 I've charged my car to 100% a few times. Rolling down the steep hill in my neighborhood, it had never decreased regen. I've always credited that to the 10% buffer.

From my observations, it appears there is a top end buffer around 4% that does not get charged and a bottom end buffer around 6% that does not get discharged. I presume the 2022 models would have a bottom end buffer that is half of that, so around 3% which is how they get from 88 kWh to 91 kWh usable for the extended range pack.

In theory, that top end buffer would get consumed first due to degradation. So if Ford hits their target of 100k miles with 5% deg then we might begin to see a range hit of around 1% sometime after 80k miles on the vehicle. Which is nothing basically. 88 kWh usable drops to 87 kWh. Not even worth measuring really.

I have observed various levels of regen based on SOC and temp. If at 100% displayed and I drive the car immediately after it finishes charging then I experience less regen compared to 100% displayed and the system has cooled for a few hours already.

Conversely, I see higher levels of regen when at 40% S.O.C or less. Haven't actually measured it but will when I get time. I can feel it though. Mainly because I can deplete the battery from 100% displayed to 30 or 40% displayed in a single day just driving around town. It is easier to notice the change when it occurs over a shorter time span I think....

 

[SnBGC]

Pretty certain this is how is works because of the physics of charging. You charge to a voltage which maps to a percent. When the degradation happens it just can't continue to build voltage to get to the target. Of course I'm taking an educated guess here... But based on this it comes off the top buffer first. Years before you'll see it.

I am thinking the same. It is just trying to hit a voltage target. It's not like there are little tiny areas of the battery that are physically sectioned off from receiving electrons.

 

[dbsb3233]

Pretty certain this is how is works because of the physics of charging. You charge to a voltage which maps to a percent. When the degradation happens it just can't continue to build voltage to get to the target. Of course I'm taking an educated guess here... But based on this it comes off the top buffer first. Years before you'll see it.

Yep. Although there's also an argument to be made for the BMS adjusting the usable battery downward on the fly to preserve that upper buffer too. The upper buffer exists to protect the battery, and that need still exists even if it's lost 10%.

Or maybe it's some combo of both (like half out of the buffer, half out of usable)?

I really have no idea. But people doing OBD2 readings don't tend to see much loss yet on either, so we're probably good for years.

 

[timbop]

From my observations, it appears there is a top end buffer around 4% that does not get charged and a bottom end buffer around 6% that does not get discharged. I presume the 2022 models would have a bottom end buffer that is half of that, so around 3% which is how they get from 88 kWh to 91 kWh usable for the extended range pack.

Yes, exactly. The battery essentially has X number of cells that are all wired in parallel, and thus charge and discharge effectively together. When the battery is "at 50%" that means every cell in the battery is charged to about half of it's theoretical capacity - there aren't any cells held "in reserve" that don't get used.

As you said, the software prevents the cells from being charged to more than about 95% of their theoretical capacity, and also prevents the car from draining the cells below roughly 3% to 5% of their theoretical capacity. As the cells begin to degrade, that means they can't be charged to their original capacity. So yes, the "top buffer" degrades first and thus no degradation is seen until the degradation reduces the capacity below 95%. The bottom buffer can never be accessed because it would mean the battery was drained completely which can render the battery inert.

 

[ZuleMME]

Yes, exactly. The battery essentially has X number of cells that are all wired in parallel, and thus charge and discharge effectively together. When the battery is "at 50%" that means each cell in the battery is charged to about half of it's theoretical capacity - there aren't any cells held "in reserve" that don't get used.

As you said, the software prevents the cells from being charged to more than about 95% of their theoretical capacity, and also prevents the car from draining the cells below roughly 3% to 5% of their theoretical capacity. As the cells begin to degrade, that means they can't be charged to their original capacity. So yes, the "top buffer" degrades first and thus no degradation is seen until the degradation reduces the capacity below 95%. The bottom buffer can never be accessed because it would mean the battery was drained completely which can render the battery inert.

Yep make no mistake the bottom buffer is FAR FAR more important to the batteries health than the top. I'd imagine they took little from the bottom for the extra 3kwh back.

 

[RedStallion]

Dumb question. Since Ford has a ~10% buffer in the pack, will degradation eat into the buffer first, or will it affect actual usable capacity first?

@OON7 @dbsb3233 I've charged my car to 100% a few times. Rolling down the steep hill in my neighborhood, it had never decreased regen. I've always credited that to the 10% buffer.

Apparently, the buffer is mostly at the bottom of the SOC and little at the top. The bottom 10% is where the battery voltage drops quickly, resulting in less power and control. But you can probably drive another 10 miles after it shows 0%.

 

[IamIA]

Assuming each DC charging session eats up is a little bit of the max battery capacity, is charging at lower charge rate but still using Direct Current cause less degradation?
I have DCFC at 25 kwh and 50 kwh a lot more then at 150 kwh.

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