Decreasing rated range.

[iKhalid]

As an example, during the last round of "balancing", I did a range charge to 100% at work where it sat 100% for maybe a half hour at most, the car reported 205 rated miles. I then drove home and did another range charge which completed at 206 rated miles, and left it at 100% overnight. I started out that morning on a road trip and stopped at a supercharger, then did a range charge at the supercharger. The supercharger range charge yielded 209 rate miles. I continued my road trip then did another range charge at my destination which yielded 209 rated miles when the charge completed. So, it seemed to me that when I left it overnight I recovered the most miles on the next charge. I understand there may be other factors involved such as the range charge at the supercharger, battery capacity calculations and such. I don't have every picture of all the completed charges with miles and time stamps to prove everything (other than keeping the picture of the best range charge yield). But I started doing the "overnight" range charges after I forgot to reset the charge slider one night and the car charged fully by accident. After that I noticed a large jump in range.

I wouldn't do what you did. I would be feeling guilty for awhile.

 

[glhs272]

I wouldn't do what you did. I would be feeling guilty for awhile.

Only blissful guilt free Tesla grins here.

 

[scaesare]

As an example, during the last round of "balancing", I did a range charge to 100% at work where it sat 100% for maybe a half hour at most, the car reported 205 rated miles. I then drove home and did another range charge which completed at 206 rated miles, and left it at 100% overnight. I started out that morning on a road trip and stopped at a supercharger, then did a range charge at the supercharger. The supercharger range charge yielded 209 rate miles. I continued my road trip then did another range charge at my destination which yielded 209 rated miles when the charge completed. So, it seemed to me that when I left it overnight I recovered the most miles on the next charge. I understand there may be other factors involved such as the range charge at the supercharger, battery capacity calculations and such. I don't have every picture of all the completed charges with miles and time stamps to prove everything (other than keeping the picture of the best range charge yield). But I started doing the "overnight" range charges after I forgot to reset the charge slider one night and the car charged fully by accident. After that I noticed a large jump in range.

Ah, so you aren't necessarily seeing the range increase after the sitting, but rather after the next full ("range") charge?

I'm not sure if that can be attributed to active balancing by charge-shuttling. I suspect that it has more to do with balancing happening at the end of a 100%, along with the algorithm having a chance to sample the battery state at 100% multiple times. Add in things like temperature fluctuation, etc... and I can easily see a few miles of variance being accounted for.

 

[Denarius]

I know that charging to 80% for a couple of months dropped my range by about 10 miles. Charging to 90% for a couple of weeks brought my range back up. I believe balancing is happening at 90%.

 

[Super Gizmo]

I know that charging to 80% for a couple of months dropped my range by about 10 miles. Charging to 90% for a couple of weeks brought my range back up. I believe balancing is happening at 90%.

I used to get 245 or so for a full Daily charge and about 265 for a Range charge until Tesla changed it to incremental Daily charge. I started charging in the middle or so of Daily range and my Daily and full range have dropped ever since. So, maybe there is something to charging to a full Daily charge to get back the range. By the way I have an A pack.

 

[AmpedRealtor]

Is it better for the algorithm to drive the car through the full SOC before recharging again, or to keep it charged to 90% even after driving 50 miles? I'm curious because I'm currently at 40% SOC and don't know if I should go back up to 90% or if I should drive it to the lower limits and then recharge. I'm thinking the latter will help the algorithm gain greater accuracy, but I'd also be pushing the pack into a low SOC of about 10%-20%.

Any suggestions?

 

[glhs272]

Ah, so you aren't necessarily seeing the range increase after the sitting, but rather after the next full ("range") charge?

I'm not sure if that can be attributed to active balancing by charge-shuttling. I suspect that it has more to do with balancing happening at the end of a 100%, along with the algorithm having a chance to sample the battery state at 100% multiple times. Add in things like temperature fluctuation, etc... and I can easily see a few miles of variance being accounted for.

Correct, the indicated rated range on the car does not increase after the car is done charging (vampires down just like after any charge). It is the next charge cycle that indicates the improved range.

 

[Super Gizmo]

Is it better for the algorithm to drive the car through the full SOC before recharging again, or to keep it charged to 90% even after driving 50 miles? I'm curious because I'm currently at 40% SOC and don't know if I should go back up to 90% or if I should drive it to the lower limits and then recharge. I'm thinking the latter will help the algorithm gain greater accuracy, but I'd also be pushing the pack into a low SOC of about 10%-20%.

Any suggestions?

That is the question no one has a clear answer to. There are so many differing opinions on various forums and from Tesla employees. I wish Tesla would give us clear guidance as to the answer. After all the health of the battery pack is very important and it is probably the most expensive component of an EV.

 

[AmpedRealtor]

That is the question no one has a clear answer to. There are so many differing opinions on various forums and from Tesla employees. I wish Tesla would give us clear guidance as to the answer. After all the health of the battery pack is very important and it is probably the most expensive component of an EV.

Thanks for the help. I've pampered this battery to no end, so I'm going to just drive it down to about 20 miles and then give it a 90% charge. Let's see what happens.

 

[BrandonF]

My MS60 was delivered at the end of June with 204 rated miles. For the first time last weekend I did a full range charge that gave me only 198 rated miles. I charge to around 80% every night (usually 155ish rated range). Should I be worried about the 198 max rated miles on a range charge? It seems like most people are getting 204-210 from what I am reading.

 

[rlang59]

My MS60 was delivered at the end of June with 204 rated miles. For the first time last weekend I did a full range charge that gave me only 198 rated miles. I charge to around 80% every night (usually 155ish rated range). Should I be worried about the 198 max rated miles on a range charge? It seems like most people are getting 204-210 from what I am reading.

I wouldn't be, try charging to 90% for a few weeks and you should see the range creep back up. That has been the case for a few of us here.

 

[magnet]

The longest life would come from from charging the pack to 51% and then discharging down to 49% and then recharging back to 51%. Never driver more than a few miles before recharging. Hahaha just kidding

In the real world...if possible...you should shoot to use only about 60% of your pack capacity. Charge to 85% and and discharge to 25% before recharging again. If you need more range don't be afraid to use more capacity. Long-term calendar life may be more tied to temperature (how hard the battery was used) than how deep you discharged and how many times you discharged (although calendar life is tied to SOC and never keep it fully charged for longer than you have to)

Don't worry about improving the accuracy of the SOC by playing tricks with deep discharge or try to leave on range charge for a few days. You will be accelerating degradation while at the same time trying to improve the range by "increasing the accuracy" of the algorithm, doesn't make any sense. You will be doing more harm than good. At the end of the day actual cell degradation is all that matters.

 

[Klaus]

My MS60 was delivered at the end of June with 204 rated miles. For the first time last weekend I did a full range charge that gave me only 198 rated miles. I charge to around 80% every night (usually 155ish rated range). Should I be worried about the 198 max rated miles on a range charge? It seems like most people are getting 204-210 from what I am reading.

This is exactly what I'm seeing. I usually charge to 80 or 85%. On a recent trip from the S.F. Bay Area to LA and back I had to do a couple of trip/range charges and was back up to 202 on the return leg.

This is with 16k+ miles, and I never got the commonly cited 206+ miles early on, more like 202-203.

 

[dennis]

suggest A owners charge at 90%. Not once, not twice, but for a month. Then see what you've got.

I have been following this advice for several months (I used to charge @80%). I am now consistently getting 228 @ 90% and 255 @ 100%. A pack, 23 months, 17,000 miles.

 

[BrandonF]

My MS60 was delivered at the end of June with 204 rated miles. For the first time last weekend I did a full range charge that gave me only 198 rated miles. I charge to around 80% every night (usually 155ish rated range). Should I be worried about the 198 max rated miles on a range charge? It seems like most people are getting 204-210 from what I am reading.

I bumped up from my usual 80% charge to 90% last night (the highest selection that isn't in the "trip" bar) and woke up with 173 rated miles. Maybe I am overreacting a bit but 173 seems low for 90%. FYI I have 6,700 miles on it and took delivery with 2,900.

 

[glhs272]

I bumped up from my usual 80% charge to 90% last night (the highest selection that isn't in the "trip" bar) and woke up with 173 rated miles. Maybe I am overreacting a bit but 173 seems low for 90%. FYI I have 6,700 miles on it and took delivery with 2,900.

173 is a bit low as I usually get 184, however don't panic yet. You won't see an increase in range after the initial charge. It will take subsequent charges to see improvement. Curious, you say your car was delivered new, and would only get 204 rated miles on a max charge? How long did you drive the car before doing your first max charge and were you charging to less than 90% right away? My car would charge to 211 rated miles the first time and 209 rated miles or so every time after. I did my first range charge within a couple weeks of receiving the car.

Edit: oops, I miss read your post, you received your car with 2,900 miles. Ok, so I wouldn't panic, just start charging at 90% for a while and see if things improve.

 

[islandbayy]

173 is a bit low as I usually get 184, however don't panic yet. You won't see an increase in range after the initial charge. It will take subsequent charges to see improvement. Curious, you say your car was delivered new, and would only get 204 rated miles on a max charge? How long did you drive the car before doing your first max charge and were you charging to less than 90% right away? My car would charge to 211 rated miles the first time and 209 rated miles or so every time after. I did my first range charge within a couple weeks of receiving the car.

Edit: oops, I miss read your post, you received your car with 2,900 miles. Ok, so I wouldn't panic, just start charging at 90% for a while and see if things improve.

I will second your recommendations. My pack was flawless with only a mile or so range loss at 34,000, and it was great until my main contactor went requiring a pack swap.
I do 100% Charges 3-5 times/week, and have done so since my car was new. Now at 38,000 miles. 4,000 on my new pack, though, my new pack is not holding up nearly as well as my original was, but thats a different story.

 

[scaesare]

Is it better for the algorithm to drive the car through the full SOC before recharging again, or to keep it charged to 90% even after driving 50 miles? I'm curious because I'm currently at 40% SOC and don't know if I should go back up to 90% or if I should drive it to the lower limits and then recharge. I'm thinking the latter will help the algorithm gain greater accuracy, but I'd also be pushing the pack into a low SOC of about 10%-20%.

Any suggestions?

I think it's worth highlighting that there are two separate (but related) issues:

- What allows the algorithm to be most accurate

- What's best for the battery pack longevity


First- The algorithm:

It must estimate overall capacity of the pack based on some direct measurements (overall min/max voltages, module min/max voltages, charge energy delivered, temp, etc...), as well as some things that can't be measured at rest state, but must be observed as the pack depletes: amount of current delivered, voltage drop over time, etc...

Some of those items (specifically voltage limits) can only be truly measured if the pack is as close to possible to 0% and 100% respectively. It is also at the upper limit of pack charge that it has a chance to most effectively balance the modules, which also eliminates any capacity loss due to a module not having a chance to balance up.

Thus, for the algorithm, full range charges and driving till shutdown, however impractical, would allow for the greatest accuracy and least range loss due to imbalance.

Secondly- The pack:

The health of the pack is best with fewer "full-equivalent" charge cycles, fewer max charges, less excursion in to low charge states, and cool temps. In other words, operate it "shallowly" in the middle of it's range as much as possible.

Although this can lead to pack imbalance, that's not harmful to the battery, just inconvenient to us. The battery management system uses the lower limits of the lowest brick, and the upper limits of the highest, to determine what to set the upper and lower discharge and charge limits, so the pack is always protected.

As can be seen, the two operational schemes are at odds with one another: Pushing the pack to it's high and low limits often is best for the algorithm accuracy and slightly improves capacity due to balancing. It's also the hardest on the pack health. This is a bit frustrating for owners (and likely gives Tesla headaches in trying to tune the display behavior).

For me: the pack health is a priority. I'm not gonna sweat a few miles of variance. My daily driving requires only a fraction of my capacity, so I normally charge to 60-70% and drive it down to about 30-35% on weekdays. On weekends I charge to 90% and may drive it down only to 70-80% at some times, or all the way down in to the 20's at others. For the occasional road trip I'll range charge, but that's becoming rarer with more superchargers sprouting up.

I likely have some inaccuracy in my range displays. I may also have some imbalance. I'm OK with that if it means my (expensive) pack is happier. My 60% charge is right at 147 rated miles. I can often drive a couple of miles before losing any estimated range, so I'm pretty close to 25 miles per 10% of range charge. (my 90% charges are at about 221, so again close). That would put me at just shy of 250 miles for a range charge (which I haven't done in months).

I'd guess that if I did a series of range charges and deep discharges, I'd gain several miles back due to balancing.. and also some due to accuracy as the algorithm learned from the greater sampling extremes... but I don't need it and if my trips are that "close to the edge", I'd probably plan alternate charging stops anyway. The number on the dash isn't enough to get worked up over...

 

[djp]

@scaesare +++1

Great summary!

 

[mknox]

@scaesare +++1

Great summary!

Yes, very useful. I have been charging to 70% and ending the day at 30 to 40% thinking I was doing my pack a favor by playing in the middle of it's range (which I guess I am). I have also been experiencing very noticeable drops in my Rated Range numbers. Even my 70% number has dropped from 217 to around 201 miles now. The reduced rated range hasn't been a "problem" as such, but is a "concern".