Top battery off to 90% every day?

[bmwhitetx]

Yeah, it says, "Ford recommends that you charge to 90% for everyday driving and charge to 100% when you need the full range for a trip. Charging to 90% helps prolong the life of your battery."
Does that mean that 90% is optimal? Or does that mean that 90% prolongs the life of the battery relative to 100% SOC? My guess is the latter.

Yeah, the latter. If 100% is for only when needed then it follows that 90% is better and < 90 even better.

As for those they say "Screw it - the battery is warranted for 100,000 miles so I'm charging to 100% everyday" then my reply is this: I bought an ER battery with 320 mile range and plan to keep it for 10 years. At the end of those 10 years I still want an ER truck with over 300 mile range, not a SR with 70% of that.

*The warranty is 8 years, 100K miles and battery capacity of 70%.

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[John Becker]

"The small delta I use will cause minimal damage to the cells, and I have enough juice no matter what the day may bring.​

​

Most of our cycling tests use 50% SOC as center point of the cycle with deltas of 30%, 60% and 90%, we have some customers using different center point SOCs. The delta of the SOC used has a greater effect than what SOC we cycle around. BTW, we use 30% SOC for long term storage and for shipping, but that is from a safety (fire risk) point of view."​

Wow! This is great intel @MickeyAO. So, you recommend charging to (pick your number) daily, regardless of miles driven or battery discharge that day?

 

[MickeyAO]

"The small delta I use will cause minimal damage to the cells, and I have enough juice no matter what the day may bring.​

​

Most of our cycling tests use 50% SOC as center point of the cycle with deltas of 30%, 60% and 90%, we have some customers using different center point SOCs. The delta of the SOC used has a greater effect than what SOC we cycle around. BTW, we use 30% SOC for long term storage and for shipping, but that is from a safety (fire risk) point of view."​

Wow! This is great intel @MickeyAO. So, you recommend charging to (pick your number) daily, regardless of miles driven or battery discharge that day?

Make sure you are comfortable that it will easily get you through the day. If that means 100%, so be it. I chose 85% because I know that is really 80% actual and I've seen the data for 75% - 80% delta on the same type of chemistry. Not that I actually get down to 75%, but I plug in every day in order to use shore power to condition the cabin the next morning.

 

[RickLightning]

Yeah, the latter. If 100% is for only when needed then it follows that 90% is better and < 90 even better.

As for those they say "Screw it - the battery is warranted for 100,000 miles so I'm charging to 100% everyday" then my reply is this: I bought an ER battery with 320 mile range and plan to keep it for 10 years. At the end of those 10 years I still want an ER truck with over 300 mile range, not a SR with 70% of that.

*The warranty is 8 years, 100K miles and battery capacity of 70%.

No, it doesn't follow that <90% is even better. Nothing that Ford states leads you to that, except you wanting it to.

In fact, versions of Mach-E and Lightning manuals say "less than 100%".

It may be better from a battery science standpoint, but there is nothing stated by Ford that implies anything less is better, or worse.

The reality is that 90% (ha!) of owners have no way to tell the impact odf their usage on battery state of health. X years down the road, they would notice no difference. In fact, they have no tool to accurately measure SOH, so they have no way to know. Car Scanner's measurment is inaccurate, varies by temp, etc.

 

[MickeyAO]

I'm just waiting for that person that says they charge their iPhone to 100% every night, so why not their EV.

I'm sure a device that cost $1k and most people will keep it for 2 years max will compare well to the life of an EV...and I don't want to hear from the people that have kept their flip phone for 18 years.

Now, if you are like me and only keep new vehicles for 3 years, you will never notice no matter how you charge and drive.

If you keep your vehicle for 7+ years, you will notice. Warranty only kicks in if you lose more than 70% of rated capacity. Have over 70% of the rated capacity but it doesn't get you through your day? Sucks to be you! Maybe if you listened to people who have actual data to base their decisions on you might have 90% of capacity in 7 years. Not saying to do what I do, but forget this 'no one knows'.

But hey, you do you Boo.

 

[John Becker]

I love the science and data to back up recommendations @MickeyAO. You are much appreciated! I trust your judgement.
Hey, what lower SOC should we seek to stay above for the purposes of SOH best practices?

 

[tnugentfl]

So much ignorance in this thread. Why charge to 90% daily when you don't need 90%. Charge to 70% if you have a short commute, charge daily and keep the delta in your SOC small, and have a healthy battery for a long time. If you're not keeping the truck long term, do the next owner a favor. The science is clear on this matter, it is utter nonsense to recommend someone to charge to 90% just because, or because of some vague language in an oversimplified owner's manual. As an early adopter of a technologically advanced piece of equipment, do better.

 

[MickeyAO]

I love the science and data to back up recommendations @MickeyAO. You are much appreciated! I trust your judgement.
Hey, what lower SOC should we seek to stay above for the purposes of SOH best practices?

20%. 30% is better, but do what you need to do for your standard routine. Don't take it down to 0% on a routine basis.

Our testing shows that a 90% delta (95% SOC to 5% SOC) has the most degradation at normal temperatures. We have what is called Test 3 (25C, max charge current, max discharge current, 90% delta) usually shows the sharpest decline with and occasional Test 8 (55C, max charge, middle discharge, 60% delta) being the first to fail testing. This is out of a 9 test L2 matrix which tests 3 temperatures, 3 deltas, 3 charge currents, and 3 discharge currents. Looking at the graphs, it is very easy to see what is the dominant and secondary factors in aging for a particular cell.

 

[MickeyAO]

So much ignorance in this thread. Why charge to 90% daily when you don't need 90%. Charge to 70% if you have a short commute, charge daily and keep the delta in your SOC small, and have a healthy battery for a long time. If you're not keeping the truck long term, do the next owner a favor. The science is clear on this matter, it is utter nonsense to recommend someone to charge to 90% just because, or because of some vague language in an oversimplified owner's manual. As an early adopter of a technologically advanced piece of equipment, do better.

The wife's EV6 charges to 90% on a daily basis only because it doesn't have 5% increments. She never knows how much driving she will do in a day (sometimes coming home at 10% SOC), so this is the best practice for her vehicle.

I should also mention we share a single 40 A EVSE.

 

[bmwhitetx]

No, it doesn't follow that <90% is even better. Nothing that Ford states leads you to that, except you wanting it to.
…
It may be better from a battery science standpoint, but there is nothing stated by Ford that implies anything less is better, or worse.

Huh? These two statements seems to be the opposite of each other.

Ford doesn’t state <90% but they are trying to sell vehicles. I would never use Ford as the only source of battery info. I trust the others posts in this thread that state otherwise. Posts from people who test batteries for a living.

I was answering the question is <90 better than 90, not if Ford thought that.

 

[Maxx]

If you need 90%, charge to 90%. In the end, your warranty will cover the battery for 70% of the original capacity for 100,000 miles.

My last truck was 20 years old when I sold it and I hope I can keep this one that long. But the question is if we are going to hold Ford to that warranty, we need to know when we dip bellow 70%. Is that my battery health? Mine is currently at 98.5%. Or is it the energy available At optimum temp? My standard pack battery at 40F and 47% actual SOC had only 38.8 KWh. What does Ford look at to honor the warranty?

Glad that works for you. Seems way, way, overcomplicated. Charging to 80% and then the next morning adding 10%? Why? And, likely won't be noticeable, as compared to others, without fancy testing.

Set charge limit to 90%. Plug in when it is at home. If we know we are going back out, don't plug in.

It only sounds complicated. My weekends are not created equal. I only do the 10% thing in winter and when I don’t know what I am doing the night before (it is not that often). It is mostly to keep the battery toasty before I leave and doing it through the app is not a hardship. I am fairly lazy. Wouldn’t do it if it was difficult. I only plug in twice or three times a week. If I had a daily routine and had to work every day, I would just program it for departure time. But I don’t.


Does anyone know what is acceptable “SOC module variation”? Mine has been as high as 0.37%

 

[VTHokies]

ahhh the 21st century version of the debate about oil changes, every 3k miles or the manufacturers recommended oil change interval!

@MickeyAO, is your testing strictly on the battery or on the entire system. Curious if it's meant to represent what the batteries see in real life EV usage with all the battery management systems keeping them at optimum conditions or if it's to test their design limits and benchmark so you know which scenarios to keep the battery out of?

 

[Jim Lewis]

I agree it's good to keep in mind that Ford's main concern is not whether your battery is in real good shape at nine years but mainly that the capacity doesn't dip below 70% in 8 years or 100,000 miles. Tom Moloughney on his State of Charge YT channel had an interview with Darren Palmer, VP of the electric division of Ford, who said that the warranty was designed to hold up and not have Ford replacing batteries even if an owner charged to 100% every day with an L2 charger for 8 years or 100K miles (https://www.f150lightningforum.com/...rging-healthier-for-battery.13085/post-298448). Given that, perhaps the charge to 90% every day also assures them that they won't have to rescue anyone who doesn't charge the battery enough and kills their truck somewhere out in the middle of nowhere from unexpectedly running out of juice. If your battery only has 70% of its capacity in 8 years and you're in a really cold environment where the cold zaps 70% of that remaining capacity in an 8-year-old battery, you'll only have 50% of the range (0.7 x 0.7 = 0.49) you had with a new truck in warm weather. And, yeah, if you buy a new $60K to $80K vehicle every 3 years, what's to worry about what you do...

P.S. If you want to know where Ford's recommendation of charging to 90% comes from, starting at about 29:08 in the YouTube video, VP Palmer states that most customers do charge at home every day to 100%. He wants to help them out by recommending that they only charge to 90% max instead. So based on that direct utterance from a Ford exec, the 90% recommendation is purely because it's better than 100% for battery longevity (and, hey!, helps insure even more that Ford won't have to fork out warranty compensation). And recommending only going to 80% was probably a dead horse because of customer range anxiety concerns (ain't gonna buy another Ford if you're not happy with range...).

The point where Palmer explains the 90% recommendation:

 

[tnugentfl]

The wife's EV6 charges to 90% on a daily basis only because it doesn't have 5% increments. She never knows how much driving she will do in a day (sometimes coming home at 10% SOC), so this is the best practice for her vehicle.

I should also mention we share a single 40 A EVSE.

This is definitely reasonable and fact based. Some of the other replies in here about charging to 90% "just because", even though the range wasn't needed isn't great info for people. This will be an expensive pack to replace one day, and good charging practices can reduce degradation significantly.

 

[RickLightning]

My last truck was 20 years old when I sold it and I hope I can keep this one that long. But the question is if we are going to hold Ford to that warranty, we need to know when we dip bellow 70%. Is that my battery health? Mine is currently at 98.5%. Or is it the energy available At optimum temp? My standard pack battery at 40F and 47% actual SOC had only 38.8 KWh. What does Ford look at to honor the warranty?



It only sounds complicated. My weekends are not created equal. I only do the 10% thing in winter and when I don’t know what I am doing the night before (it is not that often). It is mostly to keep the battery toasty before I leave and doing it through the app is not a hardship. I am fairly lazy. Wouldn’t do it if it was difficult. I only plug in twice or three times a week. If I had a daily routine and had to work every day, I would just program it for departure time. But I don’t.


Does anyone know what is acceptable “SOC module variation”? Mine has been as high as 0.37%

Have you measured "toasty"?

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