Decreasing rated range.

[tomas]

At what cost balancing? I confess to confusion. Pardon me whilst I ramble.

It seems clear from post by Odenator and Islandbay that FREQUENT range charges and significant subsequent rundowns will balance battery back to "original" rated range.
Those who have tried OCCASIONAL range charges only seem to get modest results in terms of range restoration.

All of the battery science I've gleaned from this forum says: 1) best way to avoid degradation is average ~50% SOC, so if you are not range driver, no point in range charges. 2) never leave for prolonged period in full or empty SOC.
Why on earth are Tesla service center people recommending shortcuts to balance that are inconsistent with this (leave charged 100% for 3 days)?

Seems to me that people who regularly use the battery's range (meaning drive far enough to deplete full batter at least 75%) will do frequent range charges, stay balanced and retain their rated range.
Those of us who do not regularly use the battery's range will become imbalanced and lose rated range.

What's better for battery and psyche? Contrive reasons to do range charge and 80% depletion (find places to drive and waste electricity) in order to keep battery balanced and keep peak rated range for when you need it? Or let it become imbalanced and lose peak rated range for the occasional field trip where it may be needed?

AAARRRGGG!!!??!?!

 

[J in MN]

Everyone is so fixated on range, but range is absolutely irrelevant. Range is not a physical property of the battery. Energy stored is a physical property.

It will be much more useful to compare the energy put into, or removed from the battery, to the change in state of charge. Example: Charge from 18% SOC to 65% SOC. Energy added = 28.2 kWh. Therefore battery capacity = 28.2 kWh / (0.65 - 0.18) = 60.0 +/- 0.6 kWh. It seems my car's battery is still in tip-top shape.

 

[lloyds]

Haven't tried pack balancing yet, on a RANGE charge I get 255 not yet completed. On the standard I am getting anywhere from 228 - 231 with close to 20k miles

 

[wycolo]

> My SCS told me that engineering said: [walla2]

Objection! Your Honor that is hearsay!! . . . Ok, disregard that outburst:

> 1. Charge to 100%. Leave plugged 30 minutes longer. Run down to 20%. Leave 30 minutes and then charge. Repeat 3 times.

> 2. Leave charged to 100% for 3 days without driving.

Now, when you have completed these tasks, Grasshopper, return and you will be issued more convoluted and incomprehensible chores to complete. Drink the Kool Aid, hold your head high, take a walk in the sun . . .
--

 

[apacheguy]

At what cost balancing? I confess to confusion. Pardon me whilst I ramble.

...

What's better for battery and psyche? Contrive reasons to do range charge and 80% depletion (find places to drive and waste electricity) in order to keep battery balanced and keep peak rated range for when you need it? Or let it become imbalanced and lose peak rated range for the occasional field trip where it may be needed?

AAARRRGGG!!!??!?!

I share your frustration. Why doesn't TM simply update the battery care section of the manual to bring clarity to this issue?

Now, when you have completed these tasks, Grasshopper, return and you will be issued more convoluted and incomprehensible chores to complete. Drink the Kool Aid, hold your head high, take a walk in the sun . . .

Excellent interpretation. And to answer my own question, it appears that they do not want clarity on this issue and prefer a bit of convolution and confusion. Go figure.

 

[Kraken]

Here is my real question, since if I do this, I'm planning on doing it in conjunction with my daily drive, how do I plan this to finish range charging and balancing 30 minutes prior to leaving on my commute if balancing takes an undetermined amount of time? How am I supposed to forecast when it will be finished by?

I'm down to 25 miles right now, and I'm willing to test this theory out over the next day if someone has a an answer to that question and the question of what is a preferred amperage to do this at.

 

[qwk]

Here is my real question, since if I do this, I'm planning on doing it in conjunction with my daily drive, how do I plan this to finish range charging and balancing 30 minutes prior to leaving on my commute if balancing takes an undetermined amount of time? How am I supposed to forecast when it will be finished by?

I'm down to 25 miles right now, and I'm willing to test this theory out over the next day if someone has a an answer to that question and the question of what is a preferred amperage to do this at.

It's hard to say. It can take an hour or more just sitting at 5 minutes remaining. It also varies each time.

 

[walla2]

wycolo: This is what I was instructed to do. I didn't make it up. Tesla may have made it up but again this was directed to me from Tesla Service from Tesla Engineering. What would you do in my situation? Sue them, yell at someone until you are ignored, or write something dumb on a forum and just take the lower range battery? My intent is to make lemonade, and if it requires some hoop jumping, I will jump through some hoops to get range back in my pack one way or another.

 

[lloyds]

Some updates:

3 weeks ago: 100% 258 and 90% 227 on 5.8.x (not .8)

Today 100% 260 and 90% is 232! On 5.8.8 latest 5.8.x

How many miles do you have on the car?

 

[dennis]

wycolo: This is what I was instructed to do. I didn't make it up. Tesla may have made it up but again this was directed to me from Tesla Service from Tesla Engineering. What would you do in my situation? Sue them, yell at someone until you are ignored, or write something dumb on a forum and just take the lower range battery? My intent is to make lemonade, and if it requires some hoop jumping, I will jump through some hoops to get range back in my pack one way or another.

If the decreased rated range we are experiencing is because the pack is out of balance, wouldn't the most prudent course of action be to wait for Tesla to come out with a software update that improves the pack balancing algorithm and restores our lost range? The only reason for jumping through these hoops that I can see would be someone who plans to sell their car before this [unknown] software update arrives and is worried about reduced battery range negatively impacting their sales price.

 

[wycolo]

First of all these real or virtual decreased range values are still well within the minimum winter safety extra miles allowance that we should all be imposing on ourselves as we head out across the greensward. So, as dennis suggests, prospective purchasers might be the only ones at all interested in seeing a particular number on the screen. My trip to The City every week or so starts out with 230 miles rated (or more) so I can get back with 15 miles remaining at least. If your trips are longer then you are exercising your battery even more, thus probably have a better balanced battery without even trying.

If TM Engineering is serious about certain users going thru this type of test regimen (as reported) then they should print out some log sheets & instructions. How else to do it properly?
--

 

[apacheguy]

If the decreased rated range we are experiencing is because the pack is out of balance, wouldn't the most prudent course of action be to wait for Tesla to come out with a software update that improves the pack balancing algorithm and restores our lost range?

Do we have any indication that this will be addressed in 6.0? 5.8.7 was supposed to bring "charging improvements" and many speculated this was the balancing option, but I have not noted any improvement. Furthermore, wouldn't ownership just advise owners to await the 6.0 release if this were the case?

To briefly address others who believe this to be a non-issue: Operating an imbalanced can cause significant degradation because certain cells are being cycled to much lower SOC. Therefore, this thread is about much more than just a few owners reporting that their range isn't quite as high as it used to be.

 

[ACDriveMotor]

Do we know whether 100% SOC is 100% for real on the battery? I would feel more comfortable doing a RANGE charge for balancing if I didn't worry that I was actually harming the battery by letting it sit at true 100% SOC for some length of time.

 

[hans]

Do we know whether 100% SOC is 100% for real on the battery? I would feel more comfortable doing a RANGE charge for balancing if I didn't worry that I was actually harming the battery by letting it sit at true 100% SOC for some length of time.

I'm not sure I know what a "true 100%" or "for real" SOC even means. You can keep putting more energy into a battery until it explodes. I would think that Tesla considers the cells "full" when they hit a certain voltage and then the Battery Management System (BMS) cuts the charging off and reports 100% SOC. Tesla can set that cutoff point conservatively or aggressively and it would still be considered 100%.

 

[Chris Naps]

Do we know whether 100% SOC is 100% for real on the battery? I would feel more comfortable doing a RANGE charge for balancing if I didn't worry that I was actually harming the battery by letting it sit at true 100% SOC for some length of time.

100% DISPLAYED charge is most likely extremely close to / actually 100%. I say this because it would be inconsequential for balancing to EFFECTIVELY take place if the battery is not 100%. Am example of this would be charging to 90%. If you keep continuing to recharge at 90% (balancing) does occur, but you can and most likely will notice a lower rated range after a while. If you charge to 100% a few times you will notice the battery returning to the original rated range (if REAL battery degradation has not already occurred.)

It is different when 0% is displayed. When your car shows "0%" battery, it is not actually "0%" there is left over voltage to allow for the car to remain in a low power state until help arrives in a swift period of time.


note: Charging your car to 100% is NOT bad for the battery. Lets say you charge to 100% and keep it there for a few hours, then it would impact your battery NEGATIVELY. If you charge to 100% and then immediately or within a swift period of time hop into the car and begin to deplete the battery exactly after reaching 100%, then charging to 100% will not negatively impact your battery.

 

[qwk]

Do we know whether 100% SOC is 100% for real on the battery? I would feel more comfortable doing a RANGE charge for balancing if I didn't worry that I was actually harming the battery by letting it sit at true 100% SOC for some length of time.

Tesla only charges their cells to 4.15V, or ~95%.

 

[ACDriveMotor]

note: Charging your car to 100% is NOT bad for the battery. Lets say you charge to 100% and keep it there for a few hours, then it would impact your battery NEGATIVELY. If you charge to 100% and then immediately or within a swift period of time hop into the car and begin to deplete the battery exactly after reaching 100%, then charging to 100% will not negatively impact your battery.

Can you define "within a swift period of time" since balancing can take an hour or hours to complete? Is that swift?

 

[Kraken]

Do we have any indication that this will be addressed in 6.0? 5.8.7 was supposed to bring "charging improvements" and many speculated this was the balancing option, but I have not noted any improvement. Furthermore, wouldn't ownership just advise owners to await the 6.0 release if this were the case?

To briefly address others who believe this to be a non-issue: Operating an imbalanced can cause significant degradation because certain cells are being cycled to much lower SOC. Therefore, this thread is about much more than just a few owners reporting that their range isn't quite as high as it used to be.

the only charging update I've heard anyone talk about in these late 5.x to 6.0 updates is refinements to keep people's umc chariot from cutting out as much during minor voltage fluctuations and fixes for other minor issues like maybe some European issues. I heard nothing abut balancing. Maybe some changes to calculations and displays, but not balancing. There has also been some talk that the new firmwares calculations might make the degradation less apparent due to calculation changes, but not any actual balancing.

btw, I'm writing up review of day 1 of trying this method... It'll be posted in this thread shortly...

- - - Updated - - -

Ok, so here is day one:

plugged in around 7:30 last night with 13 rated miles left.
I set it up at an amperage that said it would take 9 hours or so to finish.
9 hours would be 4:30 I the morning. I figured 1 hour to balance and then 30 minutes to sit per the method. I was leaving at 6am.
the 1 hour was purely an estimate. I have no way of knowing how long it actually took.
i checked at 5:40, and it said it wasn't charging, so it must have already finished. It said 253.
i think I originally only saw about 262. In November I remember seeing about 255(+/- 3 I'd say, I don't remember).
this means it was only about 10 miles less than it originally had.
when I got I the car 20 minutes later to leave, it was at 251.
We drove exactly 200 miles today, and I got home with 16 to spare.
We drove 70-80 most of the time, so that's where some of the miles went.
it says I used 67.2kwh.
To compare this to the last range charge I did, the driving was similar, and I drove 200 miles and got back with 7 miles.
That time, in November, conditions were similar and I actually used range mode.
from that, it seems I clearly got more out of my battery this time.
I don't know how many kwh it stores on top and bottom to keep you from bricking, but for ease of math, I'll say a total of 5kwh.
67.2/80=84%. Implying that I actually had 38 miles left at rated speed. This implies about 22 miles below zero.
I'm currently charging with the same strategy for tomorrow.

Im a little surprised but the 2 miles I instantly lost before driving, but they were likely vampire loss. With i seem to be seeing slightly more now than I did right after updating to 5.8

btw range mode was off and sleep mode was on.

 

[hans]

Im a little surprised but the 2 miles I instantly lost before driving, but they were likely vampire loss.

This is very normal. There is often and few mile "loss" immediately after the end of a charge. I have many examples in my log files. The SOC estimation techniques are less actuate when actively charging or discharging.

 

[brianman]

> 2. Leave charged ... for 3 days without driving.

I can't see myself doing this unless I'm out of state at the time (and my car isn't).

- - - Updated - - -

If the decreased rated range we are experiencing is because the pack is out of balance, wouldn't the most prudent course of action be to wait for Tesla to come out with a software update that improves the pack balancing algorithm and restores our lost range?

I'm starting a rumor that this firmware will be released on Feb 29th.