Decreasing rated range.

[bhuwan]

We should expect from the battery curves we have been presented with: 3% loss of range the first year, and 1% for every year after. I would consider normal +/- 2% at the minimum.

Bens numbers seem to fall outside of that!

 

[Lloyd]

Which member name is ben? What were his full range charge numbers? Battery capacity? Total miles? Delivery date?

If he is outside of that, then he may have a developing issue that he needs to watch.

 

[aviators99]

Of course they take 265 as the start when they figure out percentage, even though I started at 273. But my 254 is still more than 3% loss. But I don't know what "the first year" means.

 

[qwk]

Oh sorry, I forgot to post my mileage. It's 7k miles. My energy average for all of those miles is 314.

Rated range can't have anything to do with driving style(doesn't change the outcome of my charges if I drive it like I stole it).

 

[Lloyd]

Of course they take 265 as the start when they figure out percentage, even though I started at 273. But my 254 is still more than 3% loss. But I don't know what "the first year" means.

From the graph I reviewed, 'one year" was the time from when the battery first started cycling power.

I got 272 from the start on my car, and finished at 268 after 6 months and 8000 miles before it was sold. It will be at my house tomorrow for a range charge after ~ 3000 more miles on it. I will report the new range charge.

I have to believe that total energy delivered has to have some effect on battery longevity as well.

 

[cinergi]

Which member name is ben? What were his full range charge numbers? Battery capacity? Total miles? Delivery date?

If he is outside of that, then he may have a developing issue that he needs to watch.

That's me. Full rated range is now 251. 90% is 219. 85 kWh pack. 14,000 miles. Delivered 10/11/12.
One or two other people here mentioned a sudden drop to 219 as well.

 

[Lloyd]

That seems to be more than 'normal' . If it continues to drop at that rate, I would think that Tesla would step in and repair or replace.

Tesla seem to have stood behind battery issues to date. I would be watchfully concerned.

 

[aviators99]

From the graph I reviewed, 'one year" was the time from when the battery first started cycling power.

Yes, but a key component in degradation is number of cycles, which is nearly linearly related to miles driven. So the graph must assume a certain number of cycles (miles) per year. I'm sort of arguing against my own case to get my battery fixed with that statement, but not everyone is seeing degradation like I have been seeing.

 

[Owner]

So turning that into numbers...

265*.9 = 238.5

.97*265*.9 = 231

"First year is that 10K, 12K or 15K miles?"

Taking out the 5 questionable datapoints (203,265,273,275,277) the survey number average is 234 for a 90% charge, which is inline with these numbers. Perhaps a hair low.

I still am confused why they range ranges so much...

We should expect from the battery curves we have been presented with: 3% loss of range the first year, and 1% for every year after. I would consider normal +/- 2% at the minimum.

 

[bluetinc]

Once you remove the extraneous data, I think your numbers start make some good sense. You should note that you did not ask users for their true mileage which I think would create a more clear trend line from ~235 to ~220 against miles, rather you asked them for their longest trip tick distance. Some users have kept this to be their total mileage, many have not.

Also, because you are charging to 90% SOC NOT 90% of 265 miles your numbers below are a bit off. Assuming for a second that their is an 80 kWh useable battery:

90% SOC -> 72kWh -> ~5.3kWh (Reserve) + 66.7 kWh (drivable above 0 and displayed)

66.7 kWh displayed = 66.7 kWh/0.287 kWh/mi = 232 miles displayed on the dash in "rated range" mode.




My car came with ~84kWh drivable energy, which would show about 244 at 90% (275 at 100%).
Now it's about ~78kWh drivable energy, which would show about 227 at 90% (255 at 100%).

This seems inline with your data and other cars.

Peter

So turning that into numbers...

265*.9 = 238.5

.97*265*.9 = 231

"First year is that 10K, 12K or 15K miles?"

Taking out the 5 questionable datapoints (203,265,273,275,277) the survey number average is 234 for a 90% charge, which is inline with these numbers. Perhaps a hair low.

I still am confused why they range ranges so much...

 

[Owner]

My survey was trying to see if there was a relationship between driving style and rated range, as I had been told that emphatically by Tesla service personnel, so the survey was trying to see if there was that relationship. From the survey, I think that relationship is clearly debunked unless there is some short term thing, but there isn't any evidence out there on that either.

I did note that the mileage was perhaps related to total car mileage in the long report. I suspect there is some relationship in my data but definitely not certain. I think perhaps a different survey on battery degradation could be done at some point but I think we are too early for that. And plug in america has been doing those well, so I am going to assume they will be doing similar Model S surveys on that in the future.

Once you remove the extraneous data, I think your numbers start make some good sense. You should note that you did not ask users for their true mileage which I think would create a more clear trend line from ~235 to ~220 against miles, rather you asked them for their longest trip tick distance. Some users have kept this to be their total mileage, many have not.

Also, because you are charging to 90% SOC NOT 90% of 265 miles your numbers below are a bit off. Assuming for a second that their is an 80 kWh useable battery:

90% SOC -> 72kWh -> ~5.3kWh (Reserve) + 66.7 kWh (drivable above 0 and displayed)

66.7 kWh displayed = 66.7 kWh/0.287 kWh/mi = 232 miles displayed on the dash in "rated range" mode.




My car came with ~84kWh drivable energy, which would show about 244 at 90% (275 at 100%).
Now it's about ~78kWh drivable energy, which would show about 227 at 90% (255 at 100%).

This seems inline with your data and other cars.

Peter

 

[bluetinc]

Plug In America already is running a survey.

Plug In America

I encourage all to participate.


I also have heard the same for rated miles from Tesla employees. I agree that it's hogwash, but I believe that stems from the fact that different cars have different "rated miles" both at full charge and as an energy line displayed on their graphs. I believe that the energy line is set at the factory and does not change due to driving.

Peter

My survey was trying to see if there was a relationship between driving style and rated range, as I had been told that emphatically by Tesla service personnel, so the survey was trying to see if there was that relationship. From the survey, I think that relationship is clearly debunked unless there is some short term thing, but there isn't any evidence out there on that either.

I did note that the mileage was perhaps related to total car mileage in the long report. I suspect there is some relationship in my data but definitely not certain. I think perhaps a different survey on battery degradation could be done at some point but I think we are too early for that. And plug in america has been doing those well, so I am going to assume they will be doing similar Model S surveys on that in the future.

 

[gregincal]

Of course they take 265 as the start when they figure out percentage, even though I started at 273.

Which I think is absolutely fair. I had over 270 the day I drove home from the factory, but the very next time I range charged at about 2000 miles it was 265. It really seems like the batteries have a little extra capacity that degrades quickly (it doesn't seem to for some people, but they should just count themselves lucky for that). Since they only promise 265 it shouldn't matter that you get a bit extra when the car is brand new. In my opinion you can only really start to talk about degradation once the battery drops below the promised 265 and calculate the percentage from that.

 

[Owner]

I was finally get around to input my data by delaying the charge till a time when I was actually awake since my car normally charges in the middle of the night. But I could not get a full "daily charge" or non-range mode charge. The charge wants to stop just a hair before. Tried it a few times. It is 5 miles below my typical range number.

Any thoughts?

Plug In America already is running a survey.

Plug In America



Peter

 

[bluetinc]

Hi Lloyd,

Could you point me at one of the battery curves that shows only 3% loss in the first year?

We should expect from the battery curves we have been presented with: 3% loss of range the first year, and 1% for every year after. I would consider normal +/- 2% at the minimum.

Charge termination at a particular partial SOC is very hard to do consistently, especially with various charging currents. It also seems to be an area that Tesla has been trying to refine throughout the software loads. I have given up using anything except for full, 100% range charges to track my degradation, and to compare against others cars.

Peter

I was finally get around to input my data by delaying the charge till a time when I was actually awake since my car normally charges in the middle of the night. But I could not get a full "daily charge" or non-range mode charge. The charge wants to stop just a hair before. Tried it a few times. It is 5 miles below my typical range number.

Any thoughts?

 

[Lloyd]

"First year is that 10K, 12K or 15K miles?"

.

'First Year' refers to a calendar function and has nothing to do with 'Miles'

 

[brianman]

We should expect from the battery curves we have been presented with: 3% loss of range the first year, and 1% for every year after. I would consider normal +/- 2% at the minimum.

'First Year' refers to a calendar function and has nothing to do with 'Miles'

This is kind of odd, no? I thought one of the things we interpreted from prior data was that usage/cycles has a more significant impact than age except for the most extreme of "garage queens" (i.e. sub-1000 miles, 10+ years old).

Perhaps I'm misunderstanding.

 

[Lloyd]

Here are some graphs that I pulled from other sections of the forum, there are more.

Below is Model S form battery. Note higher initial drop in capacity.

Below is testing from an A123 format battery. Note the flatter and more linear curve.

Tesla battery for extended use (projected)

 

[Owner]

Well then it is actually good that I get this kind of strange not-full graph as it is sort of indicating "imperfection" in the data.

Hi Lloyd,

Charge termination at a particular partial SOC is very hard to do consistently, especially with various charging currents. It also seems to be an area that Tesla has been trying to refine throughout the software loads. I have given up using anything except for full, 100% range charges to track my degradation, and to compare against others cars.

Peter

 

[Lloyd]

Quote Originally Posted by bluetinc View Post

Hi Lloyd,

Charge termination at a particular partial SOC is very hard to do consistently, especially with various charging currents. It also seems to be an area that Tesla has been trying to refine throughout the software loads. I have given up using anything except for full, 100% range charges to track my degradation, and to compare against others cars.

Peter

That was my point in the very beginning. We only have one static charge point to track degradation, as you say at 100% (full range charge)