What's your 90%?

[FlasherZ]

Is it possible your educated cost benefit policy driven habits have carefully and exuberantly exercised your pack more than average users, and thus your pack is more agile than most? The right amount of stretch and flex before use (kind of like what my crew does every morning before work, but in your case the metaphorical "day" is actually the entire lifetime of your pack with the stretching done in its metaphorical "morning" (unmetaphorically, its adolescence))?

My apologies for too many 10 cent words. Must've been after one of those corporate meetings.

I have no idea why my pack has experienced these results. Perhaps most other packs start with a dead cell or few that places extra stress on the rest of them in the same string as well as the parallel strings, leading to more wear and tear on the remaining "good" cells, and I'm one of the very rare ones that had zero "dead pixels" when I received my refurbished pack. I really don't know.

I live in a bit of fear that I'll be the one whose pack *looks* like it has 265 miles available but the car shuts off at 15-20 miles (although my wife took it down to 25 the other day).

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I'm thinking much of what we are seeing in "losses" is really mostly out-of-calibration (to a degree!) and "set it to 90% and forget" is the best bet here. Mine is set to 90%, but I do not charge regularly. It will take me days to get back up to 90% b/c at work I charge for 3 hours at 200v/30a (17 mph) and at home I charge at 120v/12a (4 mph).

I don't agree with that. I think there are probably some cars out there that would gain a chunk of miles back if the pack were exercised to 10% and back to 100% a couple of times, but for someone with 40k miles to have a max range charge of 248-250 vs. my range of 265 seems to be more than just out of calibration.

(For what it's worth, at 19.5k, my first rev A 85 kWh pack would do a max range charge to about 248 (90% @ 226 or 228) on the older software; it had declined pretty rapidly.)

 

[apacheguy]

So is the consensus that most of rated range decline is due to

a) Range algo calibration

b) Pack balancing

c) Actual degradation

I still don't get why the pack needs to be >= 90% to balance. Based on the pack tear down (wk057), each module has a BMB that takes care of balancing at all times.

 

[FlasherZ]

So is the consensus that most of rated range decline is due to

a) Range algo calibration

b) Pack balancing

c) Actual degradation

I still don't get why the pack needs to be >= 90% to balance. Based on the pack tear down (wk057), each module has a BMB that takes care of balancing at all times.

I really haven't seen consensus appear. I don't really have an answer I've settled on.

I don't think it's "A" or most cars could recover back to 260+ just by exercising the pack, and that's not happening. Some cars do get a few miles back though.
I don't think it's "B", although some cars do get a few miles back by running it to 100% and holding it there for a bit, but not to 260+.
It could also be something else... weather, type of charging, etc., although I'm not seeing a pattern.

If I had to guess based on information I currently have, it would likely be actual degradation, although the specific forms of degradation (plating the battery poles, dead cells leading to accelerated degradation of other cells in the string, etc.) aren't known to us lay people.

 

[lloyds]

I havery 85000 on my 13 model yr. On 100%, I am at 250.

 

[Todd Burch]

I don't think it's "A" or most cars could recover back to 260+ just by exercising the pack, and that's not happening. Some cars do get a few miles back.

It's possible the algorithm has a bit of hysteresis, in that it wants to hold its previous value for a bit before moving to a new value. So exercising the limits of the pack just once might not help much in improving the displayed rated range. Or it might help, but not show up for a bit. Just too many unknowns.

I'm still a bit confused as to why Tesla doesn't just share some official info from JB on this. It would clear up so much and put so many worries to rest.

 

[SeminoleFSU]

My 2013 S85 with 35k miles has just over 4k miles from under my belt. During the proactive contractor replacement campaign, they found rust in my battery casing and one of the exhaust vents was clogged. My batter made a trip to Freemont for refurbishment and is now back in my car.

30.5k miles 90% had 239 miles and just 35k miles 90% has 238.

Wonder if they reset the algorithm when packs are refurbished?

 

[FlasherZ]

Wonder if they reset the algorithm when packs are refurbished?

The battery calibration data is indeed reset when the battery pack is pulled and reinstalled.

 

[AmpedRealtor]

Went back to charging 60% daily and now my 100% charge has dropped from 254 miles to 248 miles. Great!

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FYI... I was told by a service advisor that they can reset the range estimate in the service screen, to which we don't have access. This temporarily restores the appearance of full range, at least until the car recalculates. I asked him if he could reset my range estimate, but he said no, they only do it on loaner cars. That might explain why almost every loaner car I've driven had full 265 mile range available at 100% even though some of the loaners had over 20,000 miles. Also take this with a grain of salt, since the service advisors aren't always correct in what they say. The same service advisor said the best way to bring my range up was by driving at 55 MPH. Clearly that's not the case, and has nothing to do with how the car calculates estimated range.

 

[apacheguy]

Try pulling the BMS fuse.

 

[waynesworld]

My P90D with only 260 miles on the odometer at 90% gives 244.3 rated miles and 315.6 ideal miles.

 

[Sparrow]

A few weeks a go my 90% was 205 and 100% 228. I have charged to 100% a couple of times driven the car down to 17 miles of range once and have been charging to 90% regularly. My 90% went up to 210 and my 100% went up to 235.

 

[smartypnz]

90% 221 miles

 

[yobigd20]

Two weeks in and my 90D is only charging to 252 rated miles at 90%, down from 256. Not sure if it's just a bug in the charge limit setting or something about my driving/charging habits, but I won't stress over it too much.

the range fluctuates. its not degredation, theres lots of various factors. this topic comes up on the forums all the time. there is no way to accurately calculate the lithium ion battery capacity so it's just a bunch of algorithms and software estimates that cause the rated range to float around. that and the thousands of battery cells that make up the entire pack don't stay at "exactly the same" state of charge and there are slight differences in them over time which leads to slightly imbalanced battery packs. this will result in slightly less range showing over time but it is important to note that this is *NOT* degredation. the battery packs do balance themselves and sometimes it will "jump back up" and gain those so called "lost miles" back. usually happens if you deplete your battery and do a bunch of repeated 100% charges. then the "algorithms and estimates" get more accurate again thus the spike in range. it's a little complicated but dont stress over it, again its not actual battery degredation. I'm at 85k miles now on my MS so I see this happen all the time from personal experience. its nothing to worry over to really bring up once you are aware of how it works.

 

[AmpedRealtor]

Try pulling the BMS fuse.

This will reset the range estimate?

 

[zer0cool]

My 90% has dropped from 211 to 210 today... 3k miles, pretty new 70D... however I did a couple 100% charges in the past month, most recently 10 days ago and both times it said 135, however I was able to drive about 3.5 to 4.1 miles under heavy traffic (like rush hour bumper to bumper) + high heat (so lots of AC) before rated range dropped to 134... So the actual rated range should be around 139... but it's simply not displaying that. And the 90%, 80%, etc rated range displays are all basically treating 135 as 100%...

 

[apacheguy]

This will reset the range estimate?

Yeah I believe it did when I tried it. I would leave it out for ~5 min and then reinsert. Might need to pull touchscreen fuse as well can't remember.

 

[Todd Burch]

I typically charge to 90%, drive to work (which takes me to 78%), then at the end of the day drive home (which takes me to about 66%). On the weekends, I typcially charge back up to 90% each night and drive very little. For months, my car has consistently been charging up to 235 mi rated @ 90%.

This weekend, I tried something a little different, based on the knowledge that more fully exercising the range of the SOC gives the algorithm a better idea of where the battery's at. So I charged to 90% on Friday, but didn't plug in again until Sunday night. By that time, I was down to 49 mi rated remaining.

This morning(Monday), when I got in the car, I was at 236 rated @ 90%--so I gained a mile of indicated range by letting the car go down below 50 miles over the weekend.

 

[smartypnz]

90% 221 miles

Sorry that's with almost 65,000 miles

 

[jak]

P90D, 242 miles, 108.8 miles on the odo

 

[apacheguy]

Cause of decreasing range?

Looking at a cell discharge curve earlier today got me thinking. Folks who cycle their packs 70->30 daily, are spending all their time in the linear region of the curve. Folks who charge up to 90% daily are seeing their cell voltages rise to the non-linear, steeply curved region. Could it be that this non-linearity of the discharge curve is what makes it difficult for the range algo to estimate capacity? Also might explain why owners that deep cycle their packs down to the low end extremes also generally see improved range (as this is also non-linear and curved).

Thoughts?