What type of range degradation to be expected?

[Albatross]

Hi
i have a P85D delivered in June 2015. The rated range was consistent for a several months then dropped. Pretty consistent since but it seems low. 90% charge is 354 km? Seems low? 100 percent not even over 400 km . I look online tesla website and it seems a pipe dream.

Brad

 

[mrElbe]

My P85D with 48,000 km also gets a 90% charge of 356 kim. When I got it, it was 90% at 368 km. Now, this is all "rated range" and who knows what the calculation algorithm is.

 

[Sheffie]

I got my P85D in March 2015, have 22k on it so far, initially 90% showed 365km and now 90% shows 358km these are with Range Mode off. I'v been driving it Hard with constant launches when I can not babied at all, pretty impressed with degradation so far.

 

[Sgutz]

Looks like everyone is about the same. My 90% started at about 367km and is now 357kms, but it has been that way for at least 4 months now. My general charge pattern is to plug in when I get home regardless of the range remaining if that matters.

 

[Albatross]

I plug in too whenever home and typically charge to 90 % and leave it at that. Very occasionally I will do 100%.

 

[beeeerock]

When I spoke with a service tech a few months ago, I asked about degradation and the rated range numbers. His inference was that we shouldn't read too much into the exact numbers. He said that he understands that the calculation can change from firmware to firmware and that how the battery pack has been discharged and charged (upper and lower percentages) could change what the algorithm thinks that magic number could be. But... big but... that didn't necessarily mean that the battery pack is more or less degraded than another exhibiting a different range number.

After that conversation I decided to worry less about the actual number and instead be aware of any sudden and significant changes.

 

[Albatross]

When I spoke with a service tech a few months ago, I asked about degradation and the rated range numbers. His inference was that we shouldn't read too much into the exact numbers. He said that he understands that the calculation can change from firmware to firmware and that how the battery pack has been discharged and charged (upper and lower percentages) could change what the algorithm thinks that magic number could be. But... big but... that didn't necessarily mean that the battery pack is more or less degraded than another exhibiting a different range number.

After that conversation I decided to worry less about the actual number and instead be aware of any sudden and significant changes.

I entirely agree. Just caught me by surprise at first when about 3 months in I wasn't even getting 400 Kms on a max charge. I was worried it would keep on going. But actually has totally stabilized. But now that you mention it was after a firmware upgrade. Hmmmm

 

[dmd2005]

My 90% on the our first 90D was 415 and is now 401 after 4 months and 6000KM. The range went down when I also swapped out 19" wheels to 21" turbines...maybe I should reset the tires/wheels to 19" sizing and see if that bumps up the range a few kilometers.

 

[Peter_M]

After 2 years and 46,000 km, my 90% rated range is 369 km, which translates to 410 km at 100%. This corresponds pretty closely to the numbers I heard somewhere: expect 3% degradation in the first year and 1% per year after that. I had 430 km at 100% at delivery, but Tesla quoted 425 and I don't think I ever saw higher than 425 after that.

I charge to 85% daily, 95% for trips, and only very rarely to 98% or 100% if I really need it in the winter. If I charge above 90%, I try to time it to be done charging not more than a couple of hours before I leave.

All this his is based on the fact that the biggest factor in Li-ion cell capacity degradation is the total time spent at or near 100% or 0%, particularly at high temperatures.

 

[Albatross]

After 2 years and 46,000 km, my 90% rated range is 369 km, which translates to 410 km at 100%. This corresponds pretty closely to the numbers I heard somewhere: expect 3% degradation in the first year and 1% per year after that. I had 430 km at 100% at delivery, but Tesla quoted 425 and I don't think I ever saw higher than 425 after that.

I charge to 85% daily, 95% for trips, and only very rarely to 98% or 100% if I really need it in the winter. If I charge above 90%, I try to time it to be done charging not more than a couple of hours before I leave.

All this his is based on the fact that the biggest factor in Li-ion cell capacity degradation is the total time spent at or near 100% or 0%, particularly at high temperatures.

Thanks Peter that is helpful. I made a mistake when I first got mine and it wasn't charging right to 100 percent before a trip. I thought maybe an issue with the public charger I was using so I tried to override it and restart the charging immediately 2-3 times. Then I got a warning that charging to 100 percent might impact on the battery. It was after that I saw the first drop. I'm at 354 I'm for my p85d at 90 percent now
since then I obviously assume the car shuts down charging and I only go to 90 percent. Maybe since then once to 100 on a trip to go to Toronto.

Do do you think much difference between 90 or 85 ?

 

[Peter_M]

Do do you think much difference between 90 or 85 ?

There shouldn't be any difference because Tesla says it's safe to charge to 90% every day, but I thought I'd give it a bit of extra margin. I can't say for sure that it has helped, but I don't need the extra 5% for daily driving and it makes me feel that I'm doing whatever I can to prolong the battery life. Based on the small number of data points in this thread (very unscientific), maybe it is helping.

 

[SmartElectric]

Don't worry about changing to 100 for a trip, we do that most weekends in the winter. As others noted, when charging to 100, time it so you leave within a few hours. We're going 250 km round trip tomorrow and we'll start with a full charge.
Our car has 70000 km on it, daily changed to 90% and hasn't lost any range in the past 6 months of ownership. No idea what the previous owner did, but it charged to 97% original capacity when we bought it CPO from Tesla.

 

[jdw]

A log of what Visible Tesla reports for my July 85D (9000km), with a couple of Remote S numbers over the past 5 weeks or so. My charging pattern is a timed-for-when-I-leave charge to 90% every day. I usually end the day with 69-72% charge remaining. Three range charges in this time, one to 100% at home, one to 100% at a SC, one to 93% and one lower charge to 70%. I tend to not charge on the weekends, typically running down to 50% or so.


Dec 2 100% 266 Rated, 335 Ideal - 428 rated,539 Ideal
Dec 3 90% 239.66 Miles Rated - 384.7km
Dec 4 90% 239.04 384.1km
Dec 7 90% 239.04 Rated, 301 ideal - 384.7km, Ideal 485
Dec 8 90% 239.045 Rated, 301 ideal - 384.7km, Ideal 485
Dec 9 90% 239.04 Rated, 301 ideal - 384.7km, Ideal 485
Dec 10 90% 239.04 Rated, 301 ideal - 384.7km, Ideal 485
Dec 11 90% 238.97 Rated, 301 ideal - 384.6km, Ideal 485
Dec 14 90% 239.04 Rated, 301 ideal - 384.7km, Ideal 485
Dec 15 90% 239.04 Rated, 301 ideal - 384.7km, Ideal 485
Dec 16 90% 238.97 Rated, 301 ideal - 384.6km, Ideal 485
Dec 16 93% Ideal 500
Dec 17 90% 239.04 Rated, 301 ideal - 384.7km, Ideal 485
Dec 18 90% 238.97 Rated, 301 ideal - 384.6km, Ideal 485
Dec 21 90% 239.04 Rated, 301 ideal - 384.7km, Ideal 485
Dec 22 90% 239.35 Rated, 301 ideal - 385.2km, Ideal 485.7
Dec 23 90% 238.97 Rated, 301 ideal - 384.6km, Ideal 485
Dec 30 70%186.04 Rated, 235 ideal - 299.4km, Ideal 377.5
Jan 4 90% 238.35 Rated, 300.5 ideal - 383.6km, Ideal 483.6
Jan 5 90% 238.66 Rated, 300.93 ideal - 384.1km, Ideal 484.3
Jan 6 90% 238.66 Rated, 300.93 ideal - 384.1km, Ideal 484.3
Jan 7 90% 238.66 Rated, 300.93 ideal - 384.1km, Ideal 484.3 (Remote S 239.66 Miles)
Jan 8 90% 238.66 Rated, 300.93 ideal - 384.1km, Ideal 484.3
Jan 11 90% 238.97 Rated, 301 ideal - 384.6km, Ideal 485
Jan 12 90% 238.66 Rated, 300.93 ideal - 384.1km, Ideal 484.3
Jan 13 90% 239.35 Rated, 301 ideal - 385.2km, Ideal 485.7
Jan 14 90% 239.35 Rated, 301 ideal - 385.2km, Ideal 485.7
Jan 15 90% 239.72 Rated, 302.23 ideal - 385.8km, Ideal 486.4
Jan 16 90% 239.72 Rated, 302.23 ideal - 385.8km, Ideal 486.4 (Remote S 241 Miles)

 

[RedP85+]

My 90% on the our first 90D was 415 and is now 401 after 4 months and 6000KM. The range went down when I also swapped out 19" wheels to 21" turbines...maybe I should reset the tires/wheels to 19" sizing and see if that bumps up the range a few kilometers.

How do you set the tires/wheels sizing?

 

[tinanbran]

My 90% on the our first 90D was 415 and is now 401 after 4 months and 6000KM. The range went down when I also swapped out 19" wheels to 21" turbines...maybe I should reset the tires/wheels to 19" sizing and see if that bumps up the range a few kilometers.

Our 90D 90% was 424km first week and now has stabilized and is consistently 416km every day. I have found that if I am driving really hard the day before it will drop the next morning to 411km but goes back up the 416km within a week.

 

[Destiny1701]

Same with our 90D purchased end of March. Started at 425km at 90% and over the last 6 months has steadily declined to 421, 418, 415, 413 and now 411km. I'm looking at a 2.83% degrade over 6 months. Driving wise it's the same mix of some days light foot, some days enjoying the torque .

 

[Aussie Bob]

I started 2 years ago with 90% around 388. Now 2 years later and nearly 28,000 Km later My 90% reading is 382. I have not noticed a major degrade.

 

[Lon12]

I'm at 35,000 Km. 90% is 379 rated.

 

[Jaff]

For what it's worth, my Roadster after 5.5 years and 94,000 kms suffered about 10% range degradation.

 

[Doug_G]

All this his is based on the fact that the biggest factor in Li-ion cell capacity degradation is the total time spent at or near 100% or 0%, particularly at high temperatures.

No, that is not the basis for normal degradation. Time at near 100% at high temperatures will accelerate the degradation, but since Tesla water cools their packs you have to do it a LOT in order to impact the capacity.

This has been thoroughly researched by Tom Saxton, with his surveys of Tesla Roadster, Model S, and LEAF owners. LEAF owners in hot environments see accelerated degradation; the Tesla owners do not. Summary results for the Model S can be seen here: Battery Survey « Plug In America

What primarily determines the capacity degradation is number of pack cycles, i.e. how many times the pack has been discharged and recharged. (With Lithium ion chemistry ten cycles of 1/10th are pretty much the same as one full cycle.) A good proxy for pack cycles is total car mileage, assuming that average usage/km is fairly constant across the fleet. (The correlation is not perfect, i.e. total power used is more accurate, but the difference is tiny.)

Much of the scatter here is probably the accuracy of the measurement itself - it is tricky to determine the current capacity of a Lithium ion battery because of its very flat voltage characteristic. The battery control system can't easily measure it except when the battery capacity is very low and it can see the voltage dropping. The full battery condition is also based on voltage, but it's a very small change between nearly full and full. Between these limits the controller improves its current capacity estimate by basically counting how many electrons enter and leave the battery pack!

If you want to get the most accurate range estimate, drain the battery down as much as you dare, and then charge it fully. That will expose the battery control system to the full range of what your pack can do, and then it will have a much better idea of its capacity. That's why the range estimate is often more accurate after a long trip - you always end up cycling the battery down lower than usual.