Rated Miles Range Decline

asleshgt · Apr 2, 2015

Hi,
I live in Texas and normally charge my MS 85kWh every night to 70% for my daily usage and I consume between 20%-30% of the battery every day, so I start the day with 70% and 186 rated miles and end the day with about 40%-50% remaining on the battery. I have been taking note of these battery statistics almost every day since I bought the car 2 months ago and the rated miles has always been 186 miles with 70% on the battery, but since recently (3/31/2015) I noticed that the battery rated miles went down to 182 miles (by 4 miles) for 70% charge and it has been like that for the past 3 days every day. I have about 2800 miles on the car.

Is this common with MS? Has anybody faced the same issue like this?

Thanks,
Aslesh

jerry33 · Apr 2, 2015

The algorithm for rated miles changes with almost every release. Use Ideal miles, which seems to change less.

Todd Burch · Apr 2, 2015

People that charge to 70% frequently (as I once did) commonly see their rated range decline. Take heart that this is not real battery degredation, but simply an "apparent" loss based on how Tesla calculates miles remaining. Your behavior should actually be helping protect the battery.

asleshgt · Apr 2, 2015

I had the latest v6.2 installed in my car on 3/30/15 after which only i started noticing the 4 mile decline. Thanks for the tip. I will start tracking the ideal miles from now on and see how it goes.

jerry33 said:
The algorithm for rated miles changes with almost every release. Use Ideal miles, which seems to change less.

- - - Updated - - -

Thanks for the details. Just curious, you used to charge to 70% but looks like not anymore....any reason why you changed it? What % do you do now and do you still see the rated miles go down after each version upgrade in ur car?

Todd Burch said:
People that charge to 70% frequently (as I once did) commonly see their rated range decline. Take heart that this is not real battery degredation, but simply an "apparent" loss based on how Tesla calculates miles remaining. Your behavior should actually be helping protect the battery.

stevezzzz · Apr 2, 2015

The periodic changes to the Rated miles algorithm don't always result in a 'loss' of range: some revs have shown a few miles of additional range. That said, some actual loss of range is to be expected, both over time and with miles driven. You're doing well by your battery with your charge regimen, and the only thing you might want to try once in a great while is to balance your battery pack (see one of the many threads on the subject). If you never test the limits of your pack's ability to accept (and deliver) a charge, the algorithm tends to drift.

The good news concerning long term pack degradation is that 1) it's worst the first year and better thereafter, and 2) real-world owner data suggest that even after 100,000 miles you'll still have over 90% of your original range. Tesla really does understand the care and feeding of a battery pack for long life.

asleshgt · Apr 2, 2015

Thanks. That helps.

stevezzzz said:
The periodic changes to the Rated miles algorithm don't always result in a 'loss' of range: some revs have shown a few miles of additional range. That said, some actual loss of range is to be expected, both over time and with miles driven. You're doing well by your battery with your charge regimen, and the only thing you might want to try once in a great while is to balance your battery pack (see one of the many threads on the subject). If you never test the limits of your pack's ability to accept (and deliver) a charge, the algorithm tends to drift.

The good news concerning long term pack degradation is that 1) it's worst the first year and better thereafter, and 2) real-world owner data suggest that even after 100,000 miles you'll still have over 90% of your original range. Tesla really does understand the care and feeding of a battery pack for long life.

sorka · Apr 2, 2015

stevezzzz said:
The periodic changes to the Rated miles algorithm don't always result in a 'loss' of range: some revs have shown a few miles of additional range. That said, some actual loss of range is to be expected, both over time and with miles driven. You're doing well by your battery with your charge regimen, and the only thing you might want to try once in a great while is to balance your battery pack (see one of the many threads on the subject). If you never test the limits of your pack's ability to accept (and deliver) a charge, the algorithm tends to drift.

The good news concerning long term pack degradation is that 1) it's worst the first year and better thereafter, and 2) real-world owner data suggest that even after 100,000 miles you'll still have over 90% of your original range. Tesla really does understand the care and feeding of a battery pack for long life.

Has anyone reported losing as much as 10% in 100K miles? The most I've seen reported so far is 6%.

Todd Burch · Apr 2, 2015

asleshgt said:
Thanks for the details. Just curious, you used to charge to 70% but looks like not anymore....any reason why you changed it? What % do you do now and do you still see the rated miles go down after each version upgrade in ur car?

I'm a fairly early adopter (reservation #1577) and am now on my second S (first was in an accident). At one point I frequently charged to 70%/80% and saw a steady decline in rated miles. Even though I knew this was not real degredation, I now charge to 90% on weekdays (I have a 45 mile commute each way to work) and to 80% on weekends.

I think the key, though, is to not get too caught up in the actual number shown. If you treat your pack decently (don't exhaust it frequently, don't leave it fully charged for a long time, etc). then your pack will be fine. What you'll find is that if you go on some longer trips where you use most of the battery and then fully charge it again, you'll see many of those miles come back. In the end, miles remaining is just a guesstimate based on a lot of complicated (and in some cases fuzzy) algorithmic estimations. Determining miles remaining in a pack is a difficult task, and Tesla does a pretty good job at it, but it's not perfect.

mknox · Apr 2, 2015

Todd Burch said:
At one point I frequently charged to 70%/80% and saw a steady decline in rated miles. Even though I knew this was not real degredation, I now charge to 90% on weekdays (I have a 45 mile commute each way to work) and to 80% on weekends.

Exact same thing here, with almost exactly the same commute. I saw my decline after a summer of charging to 70%. I now do 90% on weekdays and 70% on weekends.

I think the key, though, is to not get too caught up in the actual number shown. If you treat your pack decently (don't exhaust it frequently, don't leave it fully charged for a long time, etc). then your pack will be fine. What you'll find is that if you go on some longer trips where you use most of the battery and then fully charge it again, you'll see many of those miles come back. In the end, miles remaining is just a guesstimate based on a lot of complicated (and in some cases fuzzy) algorithmic estimations. Determining miles remaining in a pack is a difficult task, and Tesla does a pretty good job at it, but it's not perfect.

My feelings as well!

stevezzzz · Apr 2, 2015

sorka said:
Has anyone reported losing as much as 10% in 100K miles? The most I've seen reported so far is 6%.

I think that's right. I was being conservative in saying 'over 90%'.

UberEV1 · Apr 2, 2015

Just to add to the data set, I charge my S85 to 90% when I'm in the country and to 70% when I'm traveling. Took delivery of car in August 2013 and now has 16,000 miles. 90% charge gives 232 rated miles, full charge gives 259, and new was 265. (B pack)

Theory is that cell balancing works best at 90% or above, but Li ion batteries don't like to hang out at max charge, so it is all about letting cell balancing occur, but not leaving battery pack at high charge states for prolonged periods of time. By keeping battery pack at 70% during extended "rests" the battery cells are happier, but some will fall out of balance and the net effect is slow decay of reported range. By returning the charge level to 90%, the cell balancing is more effective and over days (sometimes weeks), reported range will return to previously higher levels.

Hope that helps demystify some of our strange charging behaviors.

andrewket · Apr 2, 2015

I wish Tesla would define "... Leaving battery pack at high charge states for prolonged periods of time". I micro manage this, usually charging from 90 to 100% immediately before leaving, even if that means paying more per kWh. Is sitting at 100% SOC for 10 hours considered prolonged?

asleshgt · Apr 3, 2015

[Sounds good. With the change to 90% daily charge, do you still notice the rated miles decline or does it go up now?

QUOTE=Todd Burch;961085]I'm a fairly early adopter (reservation #1577) and am now on my second S (first was in an accident). At one point I frequently charged to 70%/80% and saw a steady decline in rated miles. Even though I knew this was not real degredation, I now charge to 90% on weekdays (I have a 45 mile commute each way to work) and to 80% on weekends.

I think the key, though, is to not get too caught up in the actual number shown. If you treat your pack decently (don't exhaust it frequently, don't leave it fully charged for a long time, etc). then your pack will be fine. What you'll find is that if you go on some longer trips where you use most of the battery and then fully charge it again, you'll see many of those miles come back. In the end, miles remaining is just a guesstimate based on a lot of complicated (and in some cases fuzzy) algorithmic estimations. Determining miles remaining in a pack is a difficult task, and Tesla does a pretty good job at it, but it's not perfect.[/QUOTE]

- - - Updated - - -

With the change to 90% daily charge now, do you see any increase in rated miles with each version upgrade?

mknox said:
Exact same thing here, with almost exactly the same commute. I saw my decline after a summer of charging to 70%. I now do 90% on weekdays and 70% on weekends.

My feelings as well!

Todd Burch · Apr 3, 2015

I don't usually see increases, but it charges to a consistent value each day.

UberEV1 · Apr 3, 2015

Before I implemented my version of the 90% - 70% routine, I was charging only to 65~75% daily. After some months of the consistently lower charge level, my 90% charge would only provide a range of ~226 miles. After reading the other threads on this, and learning about cell balancing, I then switched to the 90% daily charge (when I'm in town) and now I consistently charge to 232 miles rated range at 90%. But it took roughly two weeks of daily charging to 90% to move from 226 to 232.

asleshgt · Apr 3, 2015

Thanks.

Todd Burch said:
I don't usually see increases, but it charges to a consistent value each day.

- - - Updated - - -

Thanks.

UberEV1 said:
Before I implemented my version of the 90% - 70% routine, I was charging only to 65~75% daily. After some months of the consistently lower charge level, my 90% charge would only provide a range of ~226 miles. After reading the other threads on this, and learning about cell balancing, I then switched to the 90% daily charge (when I'm in town) and now I consistently charge to 232 miles rated range at 90%. But it took roughly two weeks of daily charging to 90% to move from 226 to 232.

Ugliest1 · Apr 3, 2015

andrewket said:
I wish Tesla would define "... Leaving battery pack at high charge states for prolonged periods of time". I micro manage this, usually charging from 90 to 100% immediately before leaving, even if that means paying more per kWh. Is sitting at 100% SOC for 10 hours considered prolonged?

From what I've read elsewhere on this forum, those who have done more math than me suggest "a few" hours at 100% is ok. For me, I interpret that as "less than 2".

I have yet to be in a position where I absolutely need 100% (e.g., 95% just won't do). I normally charge to 80% (however, this thread may get me to go to 90% regularly), and have only gone 100% a few times (5 maybe?) at the start of a long trip, timing the start of charging to end <2 hr before leaving in the morning. 80% currently gets me 325km (202mi), got car Jan 2014 now at 39,500km (24,500mi). Haven't gone to 100% since last summer.

ThosEM · Apr 3, 2015

I found the solution to rated range anxiety. Switch the display to "energy" in percentage points. Each point is good for about 4 km for me. It would be nice if it was 4.1 or 4.2 km, but it probably isn't.

Polly Wog · Apr 4, 2015

I've had my Tesla S85 for just under 13 months now, with just over 12,000 miles. Since getting it, I've almost always charged to either 90% or 98%. Up to now, I've never charged to 100%. Almost without fail, when I charge to 90% I get 238 rated miles, and when I charge to 98%, I get either 258 or 259 rated miles. I think I'm going to charge to 100% today, just to see what it is when it finishes.

mwulff · Apr 4, 2015

Your pack can become slightly imbalanced over time. Try for a single night to charge it up so that it reaches 100% about an hour before you need it. At that point it will sit and balance the battery-pack.

That might just help, just don't leave the car at 100%, go for a nice drive

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