2014 P85 Battery Degradation - Normal?

[JoeMartin]

So I acquired my 14 P85 in December, and am starting to wonder if my battery degradation falls within what you guys would call "normal".
This question is really being asked after reading the recent thread about the Infinite Mile Warranty.

So looking at my diagnostics, my max KWh is showing to be only 73.7 KWh.
My brother has 12 P85 and he's at 75.2 KWh, but his battery was replaced around 18 months ago with a refurb.

At 80% charge it looks like my battery banks are all right around 4 volts with very minor deviation.
I charge to 95% every Friday to get me through the weekend, and typically am recharging at around the 40% mark.

What're your thoughts?

 

[Troy]

The 85 kWh pack has 77.5 kWh usable capacity when new (source) which means your remaining capacity is 73.7/77.5= 95.1%. On average, this amount of degradation is expected at 44,000 miles based on the chart here. Whether your degradation is above or below the average depends on your mileage. However, generally speaking, 95% capacity is very typical for a used Tesla.

Ideally, you should try to keep it between 50-90% instead of 40-95%. If you can, you should switch to charging every day and set it to 90%. Here is a relevant chart.

I'm guessing you are using TM-spy to measure capacity. I wonder what your rated range is at 100%. If you didn't use TM-spy, we would try to guess your battery capacity from rated range at 100%. I would expect it to show 0.951*267= 254 miles at 100% based on the 73.7 kWh you are reporting.

In case you have the 21" wheels and you are wondering what range you would get if you switch to 19" or in case you have ever thought about switching to a Model 3 with more range, check out the range table here. 19" vs 21" would be 12% more.

 

[JoeMartin]

Thank you for the response.
I'm currently at 58,xxx miles, so it does seem to be in line then with what I should see.

 

[HMARTINPT]

The 85 kWh pack has 77.5 kWh usable capacity when new (source) which means your remaining capacity is 73.7/77.5= 95.1%. On average, this amount of degradation is expected at 44,000 miles based on the chart here. Whether your degradation is above or below the average depends on your mileage. However, generally speaking, 95% capacity is very typical for a used Tesla.

Ideally, you should try to keep it between 50-90% instead of 40-95%. If you can, you should switch to charging every day and set it to 90%. Here is a relevant chart.

I'm guessing you are using TM-spy to measure capacity. I wonder what your rated range is at 100%. If you didn't use TM-spy, we would try to guess your battery capacity from rated range at 100%. I would expect it to show 0.951*267= 254 miles at 100% based on the 73.7 kWh you are reporting.

In case you have the 21" wheels and you are wondering what range you would get if you switch to 19" or in case you have ever thought about switching to a Model 3 with more range, check out the range table here. 19" vs 21" would be 12% more.

I use to charge my battery to 90% daily like you advised. Tesla is now telling me to charge to 50-70% on the weekends and leave unplugged over the weekend when I am not planning on using the vehicle. Of course I have over 240000 miles on my vehicle so I don’t know if they advise that for everyone.

 

[shred86]

The 85 kWh pack has 77.5 kWh usable capacity when new (source) which means your remaining capacity is 73.7/77.5= 95.1%. On average, this amount of degradation is expected at 44,000 miles based on the chart here. Whether your degradation is above or below the average depends on your mileage. However, generally speaking, 95% capacity is very typical for a used Tesla.

Ideally, you should try to keep it between 50-90% instead of 40-95%. If you can, you should switch to charging every day and set it to 90%. Here is a relevant chart.

I'm guessing you are using TM-spy to measure capacity. I wonder what your rated range is at 100%. If you didn't use TM-spy, we would try to guess your battery capacity from rated range at 100%. I would expect it to show 0.951*267= 254 miles at 100% based on the 73.7 kWh you are reporting.

In case you have the 21" wheels and you are wondering what range you would get if you switch to 19" or in case you have ever thought about switching to a Model 3 with more range, check out the range table here. 19" vs 21" would be 12% more.

The pack capacity you see in TM-Spy is supposedly the total battery capacity, not usable. If that's the case, the 85 kWh pack has ~81.5 kWh total capacity, according the findings by Jason Hughes, so 73.7/81.5 = 90.4%. Has anyone measured a new 85 kWh battery with TM-Spy? I'm curious what the pack capacity reads.

That being said, I'm starting to think TM-Spy is actually showing the total usable capacity. This post shows someone who ran the car to 0% and you can see TM-Spy is still showing 3.8 kWh in the battery. He was able to drive an additional 17 miles using 4.0 kWh before Tm-Spy was indicating 0 kWh in the battery, so obviously you're still able to drive before the car will shut down to protect the batteries. At 0 kWh indicated in TM-Spy, the battery cells are indicating 3.0V, which seems to align with where most lithium-ion batteries are considered "empty", and still above the protection circuit to prevent over-discharging the batteries.

@JoeMartin, here's a post I made in another thread that summarizes a lot of the information I've found on battery degradation. It's a little lengthy but hopefully gives some insight to why various charging states are recommended. I would not charge >90% unless you need it for a long range trip. Most will agree somewhere between 50-90% is ideal, but the only recommendation I've seen that is explainable is 70% being the best charging state for minimizing battery degradation, which is what Jeff Dahn recommends. Shallow depths of charge are also better than deeper depths of charge, like @Troy mentioned which the graph he linked to illustrates. If you have a charger at home, it's recommended to keep it plugged in when you're home and don't wait to charge.

 

[evalst2018]

All,

Could you kindly share your degradation metrics on your Tesla Model S. I too have had about 13% degradation, and Tesla is not willing to stand behind their product. As a proud owner and a shareholder, I am very disappointed by this. I have other Evs, and the degradation has been nothing close to this. I do feel the 90-pack has some issues that have not been present in the 85.

I have created a public Google sheet aimed at tracking Tesla Model S degradation vs Mileage. Can you share your numbers:

Tesla Model S Battery Degradation

(Please share and circulate this post)

 

[Troy]

@evalst2018, there is an active survey here.

 

[TMThree]

I charge to 95% every Friday to get me through the weekend, and typically am recharging at around the 40% mark.

What're your thoughts?

In your shoes, I wouldn't be charging to 95%

You'd be a lot better off charging to 85% and then recharging at 30%

The battery damage occurs from reaching near 100%. Further you get from it (80% or even better, 70%) the better.

 

[Lasttoy]

I have an antique, I used to look at kw. I talked with both Fremont and local sc. Both suggested to look at mileage. They told me to set local charging at 70% (170 miles). Leave it plugged in at night. They sent me attached page out of manual.
They said when I go on long trips to charge somewhere above 225 miles.
I got new motor a few weeks ago, I have noticed it uses a lot more charge. I go on same trip to Jax and back every week. It is taking at least 10 more miles for trip. I went to Orlando Monday, it took 25 more miles each way.

 

[sorka]

I use to charge my battery to 90% daily like you advised. Tesla is now telling me to charge to 50-70% on the weekends and leave unplugged over the weekend when I am not planning on using the vehicle. Of course I have over 240000 miles on my vehicle so I don’t know if they advise that for everyone.

If you follow their advice, your battery might not die in time to be replaced under warranty before the 8 years is up

 

[sorka]

The pack capacity you see in TM-Spy is supposedly the total battery capacity, not usable.

Nope.

 

[sorka]

My round trip commute is 260 miles. All trips for me are long trips.

 

[shred86]

Nope.

Thanks for reminding me about this post, lol.

Correction to my previous post, TM-Spy reports “Nominal Full Pack Energy” from the CAN3 ID 0x0382 as “Pack” in the app. It’s basically the “usable” pack capacity, but not necessarily completely usable (except in some cases where folks have driven well beyond 0% displayed) since we now know the 4 kWh buffer is used as a fudge factor on the bottom end as reported by wk057.

 

[Lasttoy]

Soraka, u r probably right. That would s___. I was told when my motor was replaced , if my battery died, I would get a 90. They dont make 85 anymore. A ranger budy told me rumor is I could a 100 upgrade for a few grand. He said he was told in 2019 they r same pack, just set by software.
There was argument at SC what my new warranty is on my drive unit? NO ONE KNEW THE ANSWER. A guy found an email that said 2 yrs. But no official word from Fremont on paper?