What's the truth about charging to 100%?

[janstubbs]

You are being fooled by the GOM, your high voltage battery is at 93% health, so you've had about 7% capacity loss since new. That's a totally normal amount for a battery approaching 4 years old.

There have been studies on this, it's not just charging to 100%, it's the time spent at 100% which causes increased degradation. So an overnight charge to 100%, then a drive the next day is not the worst thing, but leaving it at 100% for days or weeks would be. Lower voltage is easier on the battery, the science backs this up which is why charge limits of 80-90% are becoming commonplace on lithium battery systems. I still recommend only charging to 90% daily unless you need the extra miles, the lower voltage will help prevent damaging side reactions.

I believe the GOM is programmed to show you full range at 100% even if you have some battery degradation. That cuts down on complaints.

I want to emphasize that you cannot infer battery degradation from the GOM mileage reading. It's just too variable.

So how do you gauge degradation? I am seeing minor drop in GOM range at 100% charge ( which I rarely do, usually I charge to 95% because that is enough for the common trips I do) from 245 to 241. I'ma at 52K miles on a 2022 Select base model.

Sponsored

 

[Blue highway]

So how do you gauge degradation? I am seeing minor drop in GOM range at 100% charge ( which I rarely do, usually I charge to 95% because that is enough for the common trips I do) from 245 to 241. I'ma at 52K miles on a 2022 Select base model.

Battery state of health reading from an OBD2 scanner.

 

[Sinclair63]

Battery state of health reading from an OBD2 scanner.

Do you have a recommendation on a scanner? Do they come with software?

 

[condition5]

Every winter it is clear that battery degradation is severe. Every summer it is forgotten.

This...is like a haiku. Thanks for making me smile!

 

[Snakebitten]

Do you have a recommendation on a scanner? Do they come with software?

The app called Carscanner has optimized dashboards already configured for a Mach-E. So no need for sorting through pids.

SOH is already mapped to a gauge for you.

 

[Space_Pony]

I charge at home on a 220 v/50 amp line and always to 100%. In 3 years I've never seen a range decrease.

How could you not see a range decrease when temperatures get colder?
I thought all EV's had a range decrease with colder temps.

 

[Machivy]

C-Max similar story. 21 miles Electric range when new, it was down to 6 miles before I got rid of it last month. Cell#48 was the bad apple here, throwing P0B25 (Hybrid/Electric Battery 'A' Voltage Instability) when it dipped more than 0.5V below the average cell voltage for 15 seconds. Ford was not very helpful and since the car had just passed 100K, they wanted me to spend $2500 to replace BECM and TCU (??why) before continuing so I said NO and got the Mach-E. (Strong question in my head why I stuck with Ford here, but bigger battery and LFP chemistry should alleviate my concerns)

This is interesting and nice write up. I still have my 2016 cmax energy and it has 170k miles and as of 6 months ago, the dealership said the brakes are still brand new. I live in CA and during the 'winter ' months it gets 24 miles and the other months about 30 miles on a full charge. My wife used to drive it before I got her the MME but she drove it like a Granny, meaning, on the freeway and streets she would drive it at or below the speed limits and didn't use the brakes hard at all and got a100% breaking score most of the time. Just a thought but does battery life have anything to do with driving habits, btw I'm not being sarcastic, it's an actual thought and question

 

[ChasingCoral]

The app called Carscanner has optimized dashboards already configured for a Mach-E. So no need for sorting through pids.

SOH is already mapped to a gauge for you.

Yes but I’m not sure what that battery SOH value really tells us. A year ago after lots of DCFC on my Lightning on two multi-month trips pulling the trailer, it was down to 92%. This year it’s back up to 98%.

 

[spirilis]

This is interesting and nice write up. I still have my 2016 cmax energy and it has 170k miles and as of 6 months ago, the dealership said the brakes are still brand new. I live in CA and during the 'winter ' months it gets 24 miles and the other months about 30 miles on a full charge. My wife used to drive it before I got her the MME but she drove it like a Granny, meaning, on the freeway and streets she would drive it at or below the speed limits and didn't use the brakes hard at all and got a100% breaking score most of the time. Just a thought but does battery life have anything to do with driving habits, btw I'm not being sarcastic, it's an actual thought and question

I bet so. But possibly the biggest factor with the CMax is charging in hot weather, I could never do more than 1 full charge of the battery in summer weather before it'd disable EV mode due to battery overheating. Driving habits definitely influence the heating of the battery too.

 

[Snakebitten]

Yes but I’m not sure what that battery SOH value really tells us. A year ago after lots of DCFC on my Lightning on two multi-month trips pulling the trailer, it was down to 92%. This year it’s back up to 98%.

I imagine it's telling us that Ford's own onboard algorithm for "State Of Health" can go up, just as easily as it goes down as a result of recalibration.

Or as Mach-Lee recommended, after purposely running the HVB down to the lower range of SOC (for me it was in the teens), I L2 charged to 100%.

The BMS "corrected/recalibrated/rebalanced" the HVB and the SOH algorithm resulted in an improved SOH value.

It's not that the actual electro-chemical degradation of the HVB was reversed or healed, but rather the measuring of the total battery capacity was a more accurate value, whether it increased or not.

I too watched the SOH increase over a period of time as I L2 charged to 100% about every three weeks or so. It eventually topped out at 96%, up from a low of 92%. My GTPE is a 2023.5 that sat at the dealership for ~6 months. Carscanner reports the battery now at 18 months old.

 

[Blue highway]

Yes but I’m not sure what that battery SOH value really tells us. A year ago after lots of DCFC on my Lightning on two multi-month trips pulling the trailer, it was down to 92%. This year it’s back up to 98%.

its what the BCM thinks the capacity is... deep discharge and recharge to 100% improve the accuracy (calibration) of the reading... (and helps with cell balancing).

Also keep in mind that the process to determine battery health as used by a dealer through FDRS involves basically doing charge/discharge cycles and then reading the BMS SOH figure. It is accurate less the calibration drift that occurs when we stay in the middle of pack for a long time.

 

[justalfe]

I charge my car to 100% once a week it's a 21 select.

should I stop this practice?

 

[HuntingPudel]

I charge my car to 100% once a week it's a 21 select.

should I stop this practice?

That’s up to you. The NMC battery doesn’t like dwelling at either extreme of State of Charge (SoC). If your car finishes charging and you’re driving it shortly after to get it below 90% indicated SoC, it’s probably not doing a lot of damage. If you charge it to 100% and it sits for days on end, that’s not a good idea. Likewise, if you drive it to below 10% it’s fine if you stop at a charger and bring the SoC back up in a relatively short amount of time. ??

My normal routine is to charge to 85% a few times a week and drive to work on weekdays. Some weekends see 100% and most don’t. ?‍?

Sponsored