How do you calculate Battery Degradation?

[dtbaker61]

As far as I know, Li-Ion battery degradation isn’t reversible. Looks like crap data, IMO.

Generally not reversible.... plating, dendritic formation, and cell shorts caused under load past 0 volts do not recover/repair

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[dtbaker61]

Yes the voltage of every cell is closely monitored and the BMS keeps track of the capacity of every individual cell. It’s not that hard for it to calculate the capacity. It does get less accurate over time if you never charge to 100% but it still is a decent calculation.

Also the warranty is 30%+ degradation.

Good to know
I thought it was >80% @ 100k miles

 

[portlandg]

Wondering how you could calculate the battery degradation to see the overall health of the battery and % kw available to use?
Does anyone know if you can take readings from carscanner and do a basic calc? Or FDRS. Even buying a secondhand MME this would be useful To know if the car was DCFC only which will impact the batteries performance. This could also be useful to know if something is up with your battery and sits outside the norm degradation as per warrantee.

I use an OBD11 adapter with carscannerpro app and one of the parameters you can set it to measure is HVb SoH. My MME is 18 months old, has done 12,500 miles and according to carscanner my battery SoH is at 99%

 

[breeves002]

Good to know
I thought it was >80% @ 100k miles

https://www.ford.com/support/how-to...hat-is-my-electric-vehicles-battery-warranty/

 

[dtbaker61]

https://www.ford.com/support/how-to...hat-is-my-electric-vehicles-battery-warranty/

I was thinking of some other batteries.... thanks for clarification.
<70% at 8yr/100k miles

The important thing is to realize that 70%+ at 8yrs/100k miles is NOT 'dead'.... just shorter range. Still more than enough for *most* daily drivers, and hoping that 8 years from now there really will be charge stations available every 50 miles or so for road trippers.

After that.... there would be MANY more years where the range would be enough for 'around town', or perhaps the option will exist to pull the old battery and hang it on the garage wall for battery backup, and replacing with a new battery pack of solid-state Li or whatever the next generation of battery is.

 

[RickMachE]

That isn't the reason. The reason there is a small amount of unusable battery capacity is to prevent the battery draining completely to (actual) 0%, or being charged to (actual) 100%. Both of these conditions can severely damage or shorten the life of the battery.

Actually, that is the reason. Ford has stated that. This gives them the ability, before 8 years / 100,000 miles, to release more capacity and not violate the warranty. They've already released some, the 2021 ER had 88%, the 2022+ has 91%.

I was thinking of some other batteries.... thanks for clarification.
<70% at 8yr/100k miles

The warranty is 70% or more at 8 years / 100,000 miles. Less than that would mean Ford would have to do something. They have a wide range of options.

The high voltage battery and eDrive systems of your vehicle are covered by the Electric Vehicle Component coverage for eight years or 100,000 miles, whichever comes first. High voltage battery and eDrive components covered by this warranty include the high voltage battery assembly, Bussed Electrical Center (BEC), Battery Energy Control Module (BECM), on-board charger, Inverter System Controller (ISC), DC/DC converter, and eDrive. If a covered component requires replacement under the Electric Vehicle Component warranty, it may be replaced with a new, factory remanufactured, or factory refurbished component, at Ford’s discretion. Refurbished battery components selected for your vehicle will align with your vehicle’s age and mileage and meet Ford’s requirements and standards.

 

[superdave80]

Actually, that is the reason. Ford has stated that. This gives them the ability, before 8 years / 100,000 miles, to release more capacity and not violate the warranty. They've already released some, the 2021 ER had 88%, the 2022+ has 91%.

That is not the original reason for the buffer. Even with the built in buffer, the manual still recommends not constantly charging to 100% (buffered) on a daily basis.

https://electrek.co/2021/09/29/2022-ford-mustang-mach-e-more-range/

"The difference between the total capacity and the usable capacity is called a buffer and it is used to protect the pack from excessive wear."

 

[phidauex]

In stationary energy storage we use similar buffers, and they are for both reasons - one is we can release capacity over time to stay above the contracted capacity of our system, and it also protects the battery from wear. The two things go hand-in-hand, the more excess capacity you have, the slower you can release it.

As for the 70% value, one reason for that number is that below 70% lithium battery degradation becomes non-linear, and instead of just gradually dropping to 60%, 50%, 40%, etc., it is more likely to just drop off and “die” at around 60-65%. So the conservative view is that lithium batteries between 70% and 100% SOH are healthy and fine to use, but below 70% they could fail relatively quickly.

As for individual cells failing, that wouldn’t necessarily show up as degradation, but as a cell voltage fault (which would also trigger the warranty). Getting to 70% degradation already assumes that the cells are all generally degrading at a similar rate, and that they are all basically functional. If any short, or go open, then there will be a separate fault.

 

[Mach-Lee]

FYI if you want to know how to calibrate your battery I just wrote a guide:

HV Battery Calibration Procedure

Do that, then read the battery SOH with Car Scanner in Step 6.

 

[George Knighton]

MME is way too new for any of us to be worried about battery degradation yet.

Tesla is famous for losing 10% very quickly, and then levelling out.

I don't know why this is, and most other BEV do not do that.

A Bolt EV with 154,000 over five years was proved to have lost 10%.

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