Calculating battery degradation on buying used S 85

[Lasttoy]

Tones, I have a post that gives all the parts replacement at or by 150,000 miles. But, no more expensive than my buddy with a S500 Mercedes. My car is old, and the maintenance is expensive, BUT, I'm a gearhead, this stuff is no different than any other car. Small shops now doing some of the work. I mean, brakes are same on every car. Hubs, rear axles. Window regulator. There will be a guy like Rich in Europe who buys the wreaked cars and parts them out. I lived in Germany for 10 years, there was small shop in the next town that worked on Italian exotic cars. Who would have thought, no one. He helped me get parts for my deTomaso.

 

[tonwes]

Tonwes,... Small shops now doing some of the work. I mean, brakes are same on every car. Hubs, rear axles. Window regulator. There will be a guy like Rich in Europe who buys the wreaked cars and parts them out....

Agree, a battery swap will become commonb and workshops will get familiar replacing parts, Sadly today my local bodyshop has hesitations disconnecting wires for replacing a dented door and a bumper with a new salvaged ones I sourced….

 

[IanMcL]

I have been charging my, stuck in drive, 2016 AWD Model S over a few days, contained within the 'free electricity' of my solar panels. Well you can when there is nothing better to do!

It was charging complete this afternoon.
Range displayed 252 miles.
That is the most for a long time. I reduced the input to 6 amps near the end, which translated into 3m per hour. I just wonder if that helps the process

When I purchased it 18 months ago, it charged to 257 full. Not too much loss.

 

[Lasttoy]

Doors r easy, I've changed both windows regulator and handle mechanism. Getting all the tools makes u mad, I have bag with the 6 different tools needed for doors. Bumpers are same. Tell them the entire car is 12 volts like normal car. Folks dont know that the entire car is 12 volts except high voltage systems which r ORANGE wires. I changed charge port, it had orange wires. But not connected to power.
If you pull your frunk u will see all normal stuff, BUT 2 high voltage, AC compressor and coolant heater. I changed a bad water pump. Easy, took 5 minutes. In California there r a lot of shops now, not in rest of USA.

 

[aerodyne]

85kW pack? In this case I might say "fortunately" as it would mean this battery pack is not bad at all and the car could be worthy to buy.

There is a lot of validated info on these packs on TMC. Here is a quick summary.

Nominal on a new 85 KwH is 81.5, some say 81.6, KwH.

This includes 4KwH buffer, which cannot be used in most cases, but if it is, you will be driving past zero.

So, usable new capacity is 77.5. my usable capacity after 34k miles is 71.5, and at the corrected EPA consumption gives about 237 miles of range. Note that Tesla cheats and uses the full pack to calculate Rated Range!

Biggest problem I see is buying from dealer you will possibly loose features and not have the Tesla extended warranty, you will need this to replace MCU1. It is a big risk to buy this car without a warranty for the items not covered by the batt and drivetrain warranty!

 

[tonwes]

...It is a big risk to buy this car without a warranty for the items not covered by the batt and drivetrain warranty...

Plenty of non-Tesla dealer model S cars available in the Netherlands. Due to subsidies the Netherlands was frontrunner with 5yrs operational lease contracts in 2013-2015. Al these cars are now flooding the market, with 80,000mi/140,000kms plus, so hardly eligable for extended warrantees.

I do fear maintenance costs. I have to found a non-Tesla workshop willing to take on the maintenance of a Tesla, so at this moment it is Tesla service and their price part exchange-not-repair policy.

Thus I'm torn between this 2015 model S and a 2019 model 3 with just 8,000mi/12,000 kms and factory warrantee. ALthough the model S is more luxurious, buying it would feel as a step back, as I owned a similar brand new car in 2015...

 

[Peter Lucas]

There is a lot of validated info on these packs on TMC. Here is a quick summary.

Nominal on a new 85 KwH is 81.5, some say 81.6, KwH.

This includes 4KwH buffer, which cannot be used in most cases, but if it is, you will be driving past zero.

So, usable new capacity is 77.5. my usable capacity after 34k miles is 71.5, and at the corrected EPA consumption gives about 237 miles of range. Note that Tesla cheats and uses the full pack to calculate Rated Range!

Biggest problem I see is buying from dealer you will possibly loose features and not have the Tesla extended warranty, you will need this to replace MCU1. It is a big risk to buy this car without a warranty for the items not covered by the batt and drivetrain warranty!

What is the meaning of the word "nominal" here? The usual meaning of that word in this situation is the named value. Like a 2 by 4 is only nominally a 2x4. Its actual dimensions are less. An "85 kwh" battery pack is, by definition, nominally 85 kwh. That is the name of it. Its usable capacity is less. It had a usable capacity when new. And it has a usable capacity sometime later. None of those values would be a "nominal" value. The nominal capacity is 85 kwh. What are you using the word "nominal" to mean?

 

[aerodyne]

What is the meaning of the word "nominal" here? The usual meaning of that word in this situation is the named value. Like a 2 by 4 is only nominally a 2x4. Its actual dimensions are less. An "85 kwh" battery pack is, by definition, nominally 85 kwh. That is the name of it. Its usable capacity is less. It had a usable capacity when new. And it has a usable capacity sometime later. None of those values would be a "nominal" value. The nominal capacity is 85 kwh. What are you using the word "nominal" to mean?

I understand why you have the question...

With rare exception, none of the Tesla packs are the same capacity as the badge would indicate. Jason Hughes has proven this.

I know you can find Tesla marketing materials that say a model S 85 has a 85 KwH pack, but it is not true.

The reason I use this term nominal, is that is what the CAN bus calls it. New, the MS 85 had a nominal capacity of 81.5 KwH, of which 4KwH is buffer, so 77.5 KwH usable.

In addition, range is calculated using the full pack, so you will not get rated miles at EPA rated consumption of 290 Wh/mi unless you drive past zero miles. This "Feature" also hides degradation of the battery.

18 months in, and I am just figuring this out. In the car now, and I have a car will not start message...more on this later.

 

[aerodyne]

SMT screen shot:

 

[aerodyne]

SMT screen shot:View attachment 535454 View attachment 535454

 

[Peter Lucas]

I understand why you have the question...

With rare exception, none of the Tesla packs are the same capacity as the badge would indicate. Jason Hughes has proven this.

I know you can find Tesla marketing materials that say a model S 85 has a 85 KwH pack, but it is not true.

The reason I use this term nominal, is that is what the CAN bus calls it. New, the MS 85 had a nominal capacity of 81.5 KwH, of which 4KwH is buffer, so 77.5 KwH usable.

In addition, range is calculated using the full pack, so you will not get rated miles at EPA rated consumption of 290 Wh/mi unless you drive past zero miles. This "Feature" also hides degradation of the battery.

18 months in, and I am just figuring this out. In the car now, and I have a car will not start message...more on this later.

Thanks. But I still don't know what this new definition of "nominal" refers to. It is called an "85 kwh" battery. Due to top and bottom buffers the usable capacity is 77.5 kwh. What does 81.5 kwh refer to? Doesn't matter much. Just weird.

 

[aerodyne]

Thanks. But I still don't know what this new definition of "nominal" refers to. It is called an "85 kwh" battery. Due to top and bottom buffers the usable capacity is 77.5 kwh. What does 81.5 kwh refer to? Doesn't matter much. Just weird.

Agree that the name is not representative of anything.

They could call it a 77 or 81. The choice of 85 appears to be a marketing creation.

81.5 is the total capacity of the batt, including the lower buffer of 4KwH. 77.5 + 4 = 81.5. There is no upper buffer originally..some Batts have been capped to 4.1 something from 4.2V

You can verify the total capacity of the "85" pack by looking at the Panasonic NCR 18650b cell data sheet. It gives the Watt hour capacity per cell. 7104 cells, 16 modules, 96 strings. I ran the numbers and it supports the nominal full pack size pretty close.

Tesla does not let the cells go below 3V, spec allows discharge to 2.5 V.

 

[Peter Lucas]

Agree that the name is not representative of anything.

They could call it a 77 or 81. The choice of 85 appears to be a marketing creation.

81.5 is the total capacity of the batt, including the lower buffer of 4KwH. 77.5 + 4 = 81.5. There is no upper buffer originally..some Batts have been capped to 4.1 something from 4.2V

You can verify the total capacity of the "85" pack by looking at the Panasonic NCR 18650b cell data sheet. It gives the Watt hour capacity per cell. 7104 cells, 16 modules, 96 strings. I ran the numbers and it supports the nominal full pack size pretty close.

Tesla does not let the cells go below 3V, spec allows discharge to 2.5 V.

Thanks. I get it. Marketing capacity (85 kwh). Real, new, ideal, calculated capacity (81.5 kwh) being called "nominal".

 

[aerodyne]

Thanks. I get it. Marketing capacity (85 kwh). Real, new, ideal, calculated capacity (81.5 kwh) being called "nominal".

And just now, checked the car and it has 75.3 nominal, 71.3 usable per SMT.

The only way I can get the car's displayed RR of 259, with the EPA consumption of 290 Wh/mi, is to use the higher, unobtainable nominal number. So my real degradation is 8%, and real range is like 240...

 

[Peter Lucas]

And just now, checked the car and it has 75.3 nominal, 71.3 usable per SMT.

The only way I can get the car's displayed RR of 259, with the EPA consumption of 290 Wh/mi, is to use the higher, unobtainable nominal number. So my real degradation is 8%, and real range is like 240...

So the "nominal" battery capacity is changing? If so, then I cannot imagine what "nominal" means here.

 

[aerodyne]

Yes, as the battery degrades, the nominal capacity is reduced.

The nominal cell capacity per the BMS is that between 4.2V per cell, to 3.0V per cell. But as the cells degrade, they hold less electrons and are capable of less current, hence lower KwH...

Now, some cars have been subject to battery gate, and only get say 4.15V per cell. That is a different topic entirely.

 

[Peter Lucas]

Yes, as the battery degrades, the nominal capacity is reduced.

The nominal cell capacity per the BMS is that between 4.2V per cell, to 3.0V per cell. But as the cells degrade, they hold less electrons and are capable of less current, hence lower KwH...

Now, some cars have been subject to battery gate, and only get say 4.15V per cell. That is a different topic entirely.

Okay. It's just a weird use of the word "nominal".

 

[aerodyne]

Agree....a better term would be "Total capacity remaining including buffer". I understand the M3 uses different terminology. But this is what it says now. I created a new screen on SMT to track what I think is important:

 

[Peter Lucas]

Agree....a better term would be "Total capacity remaining including buffer". I understand the M3 uses different terminology. But this is what it says now. I created a new screen on SMT to track what I think is important:

View attachment 538221

Now that I know the definitions, it makes sense. Battery degradation (battery capacity loss) equals Nominal new car minus Nominal now. Or, I suppose, it would be Useable new car minus Useable now. They should be the same. In fact, if they aren't the same, the only explanation would be that the BMS induced buffers have been changed.

 

[aerodyne]

The buffers have not changed, and regardless of which numbers are used, the degradation comes out to within 1/2% of each other.