Range Loss Over Time, What Can Be Expected, Efficiency, How to Maintain Battery Health

[PhysicsGuy]

I am confused by this...are you saying that balancing produces no benefit or that the service manual direction for brick balancing, by charging to above 4.0V per brick, is not required as it has been replaced by a more "sophisticated way"?

Could you quote the section of the service manual to which you refer?

Are you referring to balancing the 46 cells within a brick, or brick-to-brick balancing?
Again, it would be really helpful if you could quote the relevant passage from the service manual.

 

[Zoomit]

Could you quote the section of the service manual to which you refer?

Are you referring to balancing the 46 cells within a brick, or brick-to-brick balancing?
Again, it would be really helpful if you could quote the relevant passage from the service manual.

Here's the service manual text from another thread: Battery Management System - What I Learned At Tesla Service Center

The bleed resistor is applied to the brick of 46 cells (for LR battery) to ensure brick-to-brick balancing. The BMS has no further insight into battery performance than at the brick level. There's no cell-to-cell balancing within a brick, nor knowledge of any unbalance within a brick, that I'm aware of.

 

[Zoomit]

4.0 volts per brick (i.e., per cell) sounds harmless to me. That is only about 83%.

How did you determine that 4.0V is 83% SOC?

In this thread, we have been trying to determine how the 4.0V balancing limit relates to indicated SOC.

Tesla Official Statement on Range

 

[GtiMart]

I see people using the TeslaFi battery graph. Be careful that it's just an estimate. It calculates a total charge capacity at 100% based on the 80% or 90% charge you give it. I've had a few cases recently where my charge target of 80% stops at 399kms of range, which is the value used for the estimate. When I look at my car or TeslaFi a few hours later my battery shows something like 405-407km of range. The range sometimes goes up after the charge is complete. This would not be taken into account by the TeslaFi graph...

 

[duanra]

I agree, those things are not fool proof. I downloaded once an app, giving those sorts of stat. (Don't remember the name). But withing 2 hours it gave me 3 different degradation numbers with the car sitting in the garage.....i dumped the app....

 

[MarcG]

4) Never" touch the shore" or try to manipulate your state of charge in any way.

Can you please explain what you mean by this?

 

[N54TT]

Well I thought at 22k miles I leveled off to 291@100%. After the 2020.8.1 update I’ve seen a pretty big drop to now 284@100%. Will try a recalibration and see if it goes back up.

I keep hoping my degradation is going to plateau...and then I get another drop a couple weeks later. I’m down to 272@100%. SMT is showing a capacity of 66.6kwh and 14.39% degradation.

 

[duanra]

I keep hoping my degradation is going to plateau...and then I get another drop a couple weeks later. I’m down to 272@100%. SMT is showing a capacity of 66.6kwh and 14.39% degradation.

Or if it degrades enough, you'll reach 30%, and you'll get another battery, hopefully a better one.

 

[duanra]

Can you please explain what you mean by this?

Never touch the shore is a metaphore to calibration where the bms loose sight of your capacity if you don't deep cycle, hence loosing sight of the shore.
Must be explained a lot better somewhere in the forum.

 

[MarcG]

Never touch the shore is a metaphore to calibration where the bms loose sight of your capacity if you don't deep cycle, hence loosing sight of the shore.
Must be explained a lot better somewhere in the forum.

Thanks, so when @PhysicsGuy wrote “never touch the shore” does that mean don’t hit 0% SoC?

What about “manipulate your state of charge in any way”, how could we even do that?

 

[duanra]

Thanks, so when @PhysicsGuy wrote “never touch the shore” does that mean don’t hit 0% SoC?

What about “manipulate your state of charge in any way”, how could we even do that?

Here is the explanation.

Battery Degradation; Sailing & Touching a Shore

 

[ran349]

Here is the explanation.

Battery Degradation; Sailing & Touching a Shore

That was an extremely long winded answer to a simple concept, but the bottom line in it says the opposite of @PhysicsGuy; in that you should "touch the shore" occasionally to help out the BMS calibration.

 

[MarcG]

Here is the explanation.

Battery Degradation; Sailing & Touching a Shore

Thanks for the link. Makes sense to me, given the way BMS systems work. That’s why I was confused by the statement @PhysicsGuy made.

 

[SleeperService]

That was an extremely long winded answer to a simple concept, but the bottom line in it says the opposite of @PhysicsGuy; in that you should "touch the shore" occasionally to help out the BMS calibration.

I think that @PhysicsGuy 's point was that "touching the shore" is BAD for your physical battery even if it is "good" for your BMS calibration. Basically, don't start a forest fire (touch the shore) because you are a little turned around in the woods.

 

[PhysicsGuy]

I think that @PhysicsGuy 's point was that "touching the shore" is BAD for your physical battery even if it is "good" for your BMS calibration. Basically, don't start a forest fire (touch the shore) because you are a little turned around in the woods.

Yes. That is what I meant. Your physical battery, the heart of which is your cells, is very expensive, important and real. Your BMS SoC calibration is an ephemeral reflection of a piece of software.
Touching the shore is not good for your cells. The only reasons to charge above 80% are for peace of mind or to drive far. Why waste your cells finite lifetime?

In addition, there is a straightforward relationship between voltage and state of charge that to my mind invalidates the theory behind touching the shore;
92% is 41.1 Volts
85% is 40.2 V
80% is 3.97 V
65% is 38.3 V
50% is 36.9 V
35% is 36.0 V
20% is 35.0 V
12% is 34.0 V
This doesn’t really change year to year. The thing that changes is how many kilowatt hours there are between say 65% and 35%. Your battery system is never really lost. It always knows it’s percent charge even if what you’re reading on your monitor seems a little off. God only knows how Tesla managed to create a state of charge reading in miles that was so subject to manipulation and extreme error.
PS. Speaking of error, just divide all those voltages by 10. Those were actually for a 10x1 battery made with 10 21700 cells.

 

[PhysicsGuy]

Can you please explain what you mean by this?

Explained above.

 

[PhysicsGuy]

Here's the service manual text from another thread: Battery Management System - What I Learned At Tesla Service Center

The bleed resistor is applied to the brick of 46 cells (for LR battery) to ensure brick-to-brick balancing. The BMS has no further insight into battery performance than at the brick level. There's no cell-to-cell balancing within a brick, nor knowledge of any unbalance within a brick, that I'm aware of.

if that is in the service manual, I’m thinking that is maybe some thing Tesla would do at the service center after they have ascertained that your battery is is out of balance. I don’t think it’s something that individuals have to do on a regular basis.

Getting into the weeds a little bit, And this is not anything that anyone would need to know except for scientific curiosity,I would assume Tesla is measuring voltages at 97 points along the 96 brick series chain. And one could bin those adjacent voltage differences, or use Gaussians, to create a distribution graph at a particular moment in time and state of charge. And the width of that distribution graph, in volts, Would reveal your batteries state of balance. And that would be fascinating and interesting information, but as far as I know no user has been able to tap into that and look at those distribution graphs and analyze their nature and width. But presumably Tesla has all that information and they are keeping an eye on your battery, and they would tell you if it was out of balance. I would just assume this is all automated and done all the time at Tesla. So if they haven’t said your battery is out of balance, I would assume your batteries balance characteristics are OK. And I would be comfortable with that myself, Although as I mentioned before, if somebody didn’t take a trip for six months and had their state of charge 80% or below that whole time, then it would probably be a good idea to one time go to 85% even if you didn’t need to. That’s the way I look at it.

 

[Plombir]

Such a big loss... I tried recalibrate but it didn't help. Does it make sense to create ticket in technical support? Or there's nothing I can do until range drops to 30%?

 

[KenC]

Such a big loss... I tried recalibrate but it didn't help. Does it make sense to create ticket in technical support? Or there's nothing I can do until range drops to 30%?View attachment 561905

Making a ticket, even if you get nowhere, at least puts a note in the record.

 

[mrgoogle]

Such a big loss... I tried recalibrate but it didn't help. Does it make sense to create ticket in technical support? Or there's nothing I can do until range drops to 30%?View attachment 561905

I am probably that 1 dude even lower, ever since we got it new. (I am wayyy below fleet average though)

Have the SR+ also. Short story: Tesla will do nothing if it doesn’t report errors and everything “works “ capacity is Tesla’s secret! They won’t tell you the state of health. I barely used up my referral supercharges. Did all calibration stuff you can find... I have been at SeC’s for this...

Changed it to miles, because usually I use kilometers. Ours was this bad since the start, 9months later, tried all calibrations but doesnt help. Keep in mind this is not the SR non plus, but never even got that range either.