accelerated degradation concern

[cmaster]

Why are you so concerned? I am not. 160k miles and you have unlimited mile warranty for 8 years on the battery. What do you think is different if you happen to own a gasoline car?

160k miles
=====================
Oil Change 22 times @ $20 = $440
Transmission Fluid Flush @ dealer = $150
Gas @ 4848 gallons X $2.49 = $12,071.52
Coolant Flush @ dealer = $100
Cooland Hose Replacement = $100
Brakes replaced 5 times @ $80 x 5 = $400

 

[juliusa]

Should have clarified. If you peg your watts per mile at EPA consumption, can you do 244?

Yes - watt hours per mile.

 

[David99]

What do you get when you do a 100% charge? I think that would be more accurate.

I get 244 on my 5 year old S85 with 130k miles. Pretty comparable to what you are seeing.

I get 239 miles at 100% right now. Yes after 160k miles and more than 4 years that's not too bad. I'm not concerned with the overall loss, I'm concerned with the change of rate at which I lose capacity. The curve was more or less linear for a long time. Then it started to drop at a much higher rate. It's the accelerated rate I'm concerned about.

 

[supratachophobia]

Yes - watt hours per mile.

See, this is not what I'm seeing on a 90kwh pack. In no scenario could I get the rated range using EPA consumption.

 

[juliusa]

It's the accelerated rate I'm concerned about.

I think you're reading too much into some small variations of imprecise measurements. Time will tell....

On the positive side, with so many more superchargers, it is easier to get most places now with 15 miles less range than it was 4 years ago with more range.

 

[juliusa]

See, this is not what I'm seeing on a 90kwh pack. In no scenario could I get the rated range using EPA consumption.

So if you drive and it shows 286 wh/mi (or whatever it is for your 90), you don't go 1 mile for each rated mile consumed?

Not sure how that is possible, since it is just a straight calculation.

 

[mjmiron]

I agree with some of the prior posts its worth getting your car checked out. If you can please update us when you get that done I would appreciate it. I have a 85 S 2013 with 74,000 miles and I still get a full charge up to about 256 miles.

 

[David99]

I think you're reading too much into some small variations of imprecise measurements. Time will tell....

The thing is, it's not small variations. Small variations is the 'noise' you see along the curve. It goes up and down and I'm not worried about that. The rate of range loss clearly has changed at 128k miles and has been faster for the last 30k miles. Those numbers are big enough to even out those small variations. I have no clue what is going on other than a few theories.

 

[supratachophobia]

So if you drive and it shows 286 wh/mi (or whatever it is for your 90), you don't go 1 mile for each rated mile consumed?

Not sure how that is possible, since it is just a straight calculation.

Nope, It's not just a straight calculation! It should be, but it's not. From 80-100%, my car uses Nominal_Capacity to calculate rated range, then some weird nebulous number between Usable_Capacity and Nominal_Capacity (but neither) from 20% to 80%. And then below 20%, it recalculates somewhere in the teens to use Usable_Capacity for rated range remaining. This mis-estimation causes all kinds of problems with trip planning and supercharging. Plus there is a weird problem of occasionally not charging to 100% and stopping at 95% even though it's set to 100%. Not sure if the latter is related

 

[juliusa]

Nope, It's not just a straight calculation!

Mine is. It is linear from 100% down to 0%. If I use 286 wh/mi, it ticks off 1 mile of range for every mile I drive - no matter what SOC.

 

[juliusa]

The thing is, it's not small variations.

A 100% charge for me was between 243 and 245 miles on my trip last week when I did 3 range charges. It is not always the same - I think it may have to do with pack balancing. I consider that small variations, and if I plotted 243 vs 245 it would tell a very different story.

Los 240s of range for an S85 with 160k miles sounds about right to me.

 

[cwerdna]

Should have clarified. If you peg your watts per mile at EPA consumption, can you do 244?

To be clear, if you hadn't noticed, the correct units are watt hours per mile. Watts per mile doesn't make sense.

 

[AmpedRealtor]

See, this is not what I'm seeing on a 90kwh pack. In no scenario could I get the rated range using EPA consumption.

So if you drive and it shows 286 wh/mi (or whatever it is for your 90), you don't go 1 mile for each rated mile consumed?

Not sure how that is possible, since it is just a straight calculation.

The more my battery degrades, the lower the Wh/mi I need to hit in order to get rated range. When the car was new, I could get rated range if I hit about 280-285 Wh/mi. Now that number is well into the low 270s. I have to drive much more efficiently today in order to get 1:1 real miles to rated miles than when the car was new. Is this normal?

Also, in 2013 anyway, EPA rating for range was determined by driving the vehicle until the battery shut down.

 

[ran349]

The more my battery degrades, the lower the Wh/mi I need to hit in order to get rated range. When the car was new, I could get rated range if I hit about 280-285 Wh/mi. Now that number is well into the low 270s. I have to drive much more efficiently today in order to get 1:1 real miles to rated miles than when the car was new. Is this normal?

Also, in 2013 anyway, EPA rating for range was determined by driving the vehicle until the battery shut down.

Probably shouldn't change that much, but you are only talking about a few percent difference. Could your measurements have been less accurate initially? And how much has your battery degraded?
I have to drive my car at 270 Wh/mi to achieve rated miles, but I have a 70D. But that number hasn't changed noticeably with time.
I think the EPA rating is still done by driving the car until it stops. But I am not sure of that. Maybe someone else knows for sure.

 

[David99]

Quick update. I drove about another 10k miles since I posted. The degradation slowed down. It looks like it dropped faster for a while then stayed almost flat for the last 20k miles. The average degradation seems to be almost in line with the previous years.

 

[jruiz510]

Tesla told me that the batteries last 10-15 years or 500k miles what ever comes first despite infinite mile warranty or 8 years first policy.

 

[David99]

Tesla told me that the batteries last 10-15 years or 500k miles what ever comes first despite infinite mile warranty or 8 years first policy.

That's an interesting statement. Batteries don't go bad like mechanical parts, they degrade over time and use and lose capacity and performance. The general consensus among battery manufacturers is that a battery has reached the end of it's life when it lost 20% capacity. Since Tesla doesn't state any specific number for capacity loss or other performance parameters in their warranty it really is up to them to define it case by case.

From people posting here it seems when the battery shows any sudden signs of losing range or other performance, they replace them. But not those that just lose capacity normally over time (whatever normal means).

 

[David99]

I just noticed the graph is distorted! If you look at the X axis increments (miles on the odometer) it is not the same amount of miles along the X axis. It starts with much smaller increments at the left and larger ones at the right.

This distorts the degradation curve and makes the graph misleading. I sent the guys at Teslafi a message to look at it.

 

[David99]

I took the raw data and made my own chart that shows the correct X-axis spacing. The reason I don't have much data before 70k miles is because that's before I started using Teslafi.com. I did record a few points which I added in here.
Red is the trendline. Everyone is free to do their own interpretation. To me it looks like degradation isn't slowing down significantly over time. After the initial drop (first 10k miles or so), it seems, degradation is more or less steady and linear.

Two interesting things: between 60k and 100k there was very little drop. And recently, between 140k and 170k (current) it seems to be almost flat.

 

[supratachophobia]

I posted this in my original thread, but thought it would be useful here:

As promised, I have a graph for a 100% to 1% trip on a 90kwh battery, for single long contiguous trip. The red line is the depletion of the battery if Nominal Capacity is used to calculate Remaining Range for the entire trip (which matches what the car reports as starting with). The yellow/orange line is the depletion of the battery if Usable Capacity is used to calculate Remaining Range for the entire trip (which matches what the car reports as ending with).

The black line is the ACTUAL Range remaining as reported by the car, for the entire trip.

So, yes, a million lines of data proves that the car is changing what it is using to calculate Range Remaining. And it's changing between Nominal and Usable. The result is that the driver is informed of more available range than he/she actually has available at 100%, with the true remaining range only to be shown only less than 20% and most accurately at 10%.

Source data freely available to @ran349, @emir-t , @Brass Guy, @wk057, or anyone else that would like to pick apart the numbers and see if different conclusion can be drawn. But my conclusion is that Tesla is lying to 90kwh owners about the actual degradation to their batteries.....