90D Range slowly declining

[Canuck]

Try not to be so defensive on this issue. I'm an earlier adopter and did not experience this symptom that you speak of. The new 90 kWh customers paid a lot for their cars and have a right to know what is going on even if it's just Tesla messing around with the range algo. I don't think anyone is saying 90 kWh is "defective." It is a new chemistry so there are a lot of unknowns. They have a right to be reassured.

I'm trying to be helpful and to reassure them, and also to tell them what to do to find out if it really is capacity loss, or an error in the algorithm. As stated in this older thread, "the algorithm for rated miles changes with almost every release" so it really surprises me you saw no changes:

Rated Miles Range Decline

If you say so. Will it still be a bad example when 90 owners see *another* 3% drop in a month or two?

No. I will say you are correct. I have no problem admitting when I am wrong. I predict, however, it won't happen but what will happen is a change the algorithm.

That's the news and I am out of here. I was just trying to be helpful and don't need to be jumped on. Good luck folks!

 

[apacheguy]

I'm trying to be helpful and to reassure them, and also to tell them what to do to find out if it really is capacity loss, or an error in the algorithm. As stated in this older thread, "the algorithm for rated miles changes with almost every release" so it really surprises me you saw no changes:

Rated miles have changed *slightly* in some releases but certainly no where near all of them.

Still it's beside the point. What we are seeing here is very different. This is a steady, fleet wide loss of range clearly affecting the 90 kWh battery. I've been following rated range decline since Oct. 2012 and can tell you that never, ever was there a similar issue with the 85s.

Having said that, I do also agree that it is unlikely to be actual degradation and more likely that Tesla needs to do some fine tuning of the 90 BMS algos.

 

[mlebl1h]

My P85D is only showing 1 mile less rated range at 90% after 12K miles.

Excellent, that makes it easy on you! Do you do some occasional long drives that bring the battery to a low level? If not, there are always a few lucky outliers.

We're just responding to some new owners that seemed concerned about 90% charge RM drops. Some amount of drop is quite typical, especially with shallow charge-discharge cycles. Give it a few months to see if the drop stabilizes. Also, as Canuck said, range charging isn't enough to recalibrate the estimate -- the software would also need to see a low battery state.

 

[msnow]

Excellent, that makes it easy on you! Do you do some occasional long drives that bring the battery to a low level? If not, there are always a few lucky outliers.

We're just responding to some new owners that seemed concerned about 90% charge RM drops. Some amount of drop is quite typical, especially with shallow charge-discharge cycles. Give it a few months to see if the drop stabilizes. Also, as Canuck said, range charging isn't enough to recalibrate the estimate -- the software would also need to see a low battery state.

Agree and I also think what Canuck suggests (long trip/deep discharge) is a reasonable ask in order to rule it out or find the solution. My problem is that I have no long trips planned for quite a while so hopefully someone posting here can do that and report back.

Question, can I accomplish the same thing by just not plugging in for a week or so until it gets to 10-20%? My typical driving mileage is only 20-30 miles per day so it will take a while to get it down

 

[TexasEV]

Question, can I accomplish the same thing by just not plugging in for a week or so until it gets to 10-20%? My typical driving mileage is only 20-30 miles per day so it will take a while to get it down

Vampire loss is only a few miles per day. It will take a lot longer than a week or so to deplete a battery to 10-20%.

 

[apacheguy]

Vampire loss is only a few miles per day. It will take a lot longer than a week or so to deplete a battery to 10-20%.

He's saying that he will drive it 20-30 each day. Not letting it just sit there, he just wouldn't charge each night.

 

[msnow]

He's saying that he will drive it 20-30 each day. Not letting it just sit there, he just wouldn't charge each night.

^^ This. However I am told this wouldn't be a good idea as it may damage the battery. Is anyone else on this thread planning a long trip?

 

[apacheguy]

Well it damages it to the extend that shallow cycles are always better. But a couple deep discharges won't hurt. Someone feel free to contradict if I'm missing something.

 

[Zybane]

I think you guys are putting way too much stock into the computer algorithm for Range.

 

[ArtInCT]

I found this thread interesting as I will be ordering a P90D. So I went through all the 109 posts, and jotted down to the best of my limited ability, the beginning rated range reported, the current rated range and then figured out the number of days.... Put this data into a spreadsheet and then calculated the % range reduction and % range reduction by day.... Here is a jpg of the data after I sorted it from best to worst.
What you see here is there are two very prominent data points (the first and last) which are way outside of the bell curve...

But on the whole, is 1.9% rated range degradation normal? I suspect it is in the normal range based on cell data info I have come to understand.
Please see this post from this thread.... 90D Range slowly declining - Page 4

Perhaps you folks may want to create a google docs spreadsheet to keep track? Identify your data by Username?
BTW, the 251 and 263 start numbers, are out at the edges and should be revalidated (or I made a boo boo).

 

[msnow]

If you pull out the outliers (line items 5, 6, 13) how does that change the totals on line 17? I think that is the correct starting point.

 

[RJ Dibble]

Line #15 - the number of days should be 57 (Sept 9 - Nov. 4)
Thanks for doing this!

 

[ArtInCT]

Here is the data, Data that is out of range has been removed from calculations but at the bottom of the sheet.... RJ your days were changed

 

[msnow]

Nicely done Art, much appreciated.

 

[ArtInCT]

Ok, so if any new 90D owners want to report in, please post your original Rated 90% Range when new, your current rated 90% range and an estimate of the number of days
since new.

Once a week I will update this data as time allows...

BTW, is not 2% initial reduction in rated range to be expected as the "norm"?

 

[RJ Dibble]

So we hit a new low of 246 at 90% this morning (11/7/15). Charged up to 100% and reached 272 (down from ~280).
Going to take a trip to Yountville for the afternoon, about a 200 mile round trip. Will then charge up to 90% again and report the result.

RJ

 

[msnow]

So we hit a new low of 246 at 90% this morning (11/7/15). Charged up to 100% and reached 272 (down from ~280).
Going to take a trip to Yountville for the afternoon, about a 200 mile round trip. Will then charge up to 90% again and report the result.

RJ

Check it after you hit a couple of those great wineries. I'm sure it will look just fine! [emoji12]

 

[wizputer]

44 days ago (1380mi) when I left the factory SC, it said 261mi

90% is now 256mi

 

[RJ Dibble]

Yes, It was a great day in the wine country. Ate lunch at Mustard's and enjoyed the beautiful weather and the fall color in the vineyards.

However, after running the range down to 56 miles and charging back up to 90% it still shows 246 :frown:

RJ

 

[Canuck]

Yes, It was a great day in the wine country. Ate lunch at Mustard's and enjoyed the beautiful weather and the fall color in the vineyards.

However, after running the range down to 56 miles and charging back up to 90% it still shows 246 :frown:

RJ

Unless you go to 100% you won't be correcting the algorithm calculation.