V10 and Battery "Degradation"

[earthwormjim]

I have similar recordings for each charging session. The battery capacity you calculated was based on "used kWh", 38kWh / (100-17)% = 45.78kWh, if I understand it correctly. However, the battery used on that screen is only for driving. The energy it used while parking, more so when you said your log is between two days, was not included. The difference between charged and discharged energy (41 - 38 = 3kWh) was the loss while sitting idle. I would calculate the battery capacity using energy that put back into the battery, 41kWh in your case, 41kWh / (100-17)% = 49.4 kWh. This way, I have my battery calculated around 51kWh. The number does fluctuate from 49kWh to 52kWh from time to time. So I ended up using (added miles/rated miles) as a reference of % energy charged for the car. With the new method that I have, battery capacity shows 52.4 +-0.1 kWh. I know my calculation is still rough, but it serves my needs (to know the real consumption).

A very interesting fact of this is, when you look at the loss, 3kWh in your case, you can average out the power your Tesla is using while parked: 3kWh / 48hr = 62.5 Watts.

I did two deep cycles, one was continuous, with only about 30 minutes of stop time. They both yielded about 45kwh of total battery capacity. There's no way to account for the "missing" 3kwh there in its entirety with 30 minutes of stopped time. The second deep cycle through only had the car parked for roughly 24 hours, not 48hours. When the car is parked, I do not have sentry mode enabled, nor cabin cooling enabled, and I do not have smart summon. 3kwh loss while parked is excessive, and doesn't match my usual 1% (~500 wh) per day of loss.

I'm pretty sure my battery capacity is reduced slightly, but not as bad as I was fearing when I first started the re-balance procedure. The fact remains the car displays 227 miles of max range at 100% (after rebalancing), yet when I first got the car it displayed 237-240 miles of max range at 100%. That implies 2.5kwh of lost capacity.

 

[AlanSubie4Life]

They both yielded about 45kwh of total battery capacity. There's no way to account for the "missing" 3kwh there in its entirety with 30 minutes of stopped time.

Again, be careful about the different charging and discharging constants. (They are about 5% different, so that explains a portion of the discrepancy (it's hard to talk specifics without having the exact data on the charging event and the discharging event).

I first got the car it displayed 237-240 miles of max range at 100%. That implies 2.5kwh of lost capacity.

13rmi*219Wh/rmi = 2.85kWh charging capacity loss
13rmi*209Wh/rmi = 2.7kWh discharge capacity loss

 

[TomLee]

Keep in mind that charging uses a different constant (219Wh/rmi) than discharging (209Wh/rmi). These are SR numbers.



It was likely lower in this case. 41kWh added is 187 rated miles (187rmi*219Wh/mi = 41kWh), which is 39.1kWh (187rmi*209Wh/rmi) in discharge energy.

So it's closer to 1.9kWh over 48 hours which is closer to 40W, 4.6 rated miles per day, which is a more typical vampire drain number (though still a bit high - could be due to USB stick being left recording or whatever of the several other vampire-minimizing options).

(These are just approximate numbers...there's a little bit of ambiguity in the data from the original post. But just a hypothetical example of the vampire, if the trip meter showed 38kWh and the charging event (to the same original level) showed 41kWh.)

I'm quite familiar with your 5% theory , and I don't doubt about it. However, I found it's a little complicated to bring it up here. so that's why I didn't mention, but knowing you will follow up on that.

 

[AlanSubie4Life]

I'm quite familiar with your 5% theory , and I don't doubt about it. However, I found it's a little complicated to bring it up here. so that's why I didn't mention, but knowing you will follow up on that.

Understood. However, as I've said a few times, people should know that both of these numbers are pretty easy to determine yourself empirically. No reason to believe me on it!

The charging constant is really easy to derive for a large charging event. Can determine it to within about 1% if you add more than something like 20kWh during a charging session. The more the better of course.

 

[BE_M3]

You have EAP. Make sure you have Smart Summon Standby Mode turned off. This will drain significantly everywhere except at home, your work, and your favorites (if they are defined). It drains at least 16 miles per day if it is left away from all of these locations all day.

Thanks, I'll check that tonight

 

[earthwormjim]

Again, be careful about the different charging and discharging constants. (They are about 5% different, so that explains a portion of the discrepancy (it's hard to talk specifics without having the exact data on the charging event and the discharging event).



13rmi*219Wh/rmi = 2.85kWh charging capacity loss
13rmi*209Wh/rmi = 2.7kWh discharge capacity loss

You keep mentioning the constants, but they are irrelevant for calculating battery capacity if you have trip data with essentially 1 continuous trip, which I do have for my deep discharge cycle.

My first deep cycle trip, which was nearly continuous driving showed 100% battery at the start (energy display mode), and 10% at the end of the trip. Consumption showed 40.3kwh for that trip. I used 90% of the battery +/-1%. Best case, that's 45.28 kwh of theoretical battery capacity. My subsequent deep cycle attempts at balancing the battery showed similar battery capacities, although they were not single continuous trips, so they will underestimate battery capacity by however much the car consumed (1-2kwh) while sitting for ~24 hours.

When I started, I had 220 miles max range, after 3 deep cycles, I now have 227, so I definitely regained something, but not the full rated battery capacity.

 

[AlanSubie4Life]

but they are irrelevant for calculating battery capacity if you have trip data with essentially 1 continuous trip, which I do have for my deep discharge cycle.

Well, the constants are calculated from continuous trips, so they are somewhat relevant. They are just predictive shortcuts which tell you what you will get for a given continuous trip. Essentially, they're exactly the same thing as your continuous single trip datapoint.

which was nearly continuous driving showed 100%battery at the start (energy display mode), and 10% at the end of the trip. Consumption showed 40.3kwh for that trip.

90% discharge is 40.3kWh. So this implies you used 40.3kWh/209Wh/rmi = 193 rated miles on that trip segment.

So this further implies your 100% charge (at that time) was: 193rmi / 0.9 = 214 rated miles

It doesn't work out exactly but there is rounding error (since you were using energy display), and any losses while in park would bias you towards a low estimate. (Say you lost a couple miles after disconnecting before you started driving, and furthermore due to rounding error you actually were closer to 89% used - that would mean (193+2)/0.89 = 219 rated miles.) In any case, the constant works out super close, even with these potential error sources. There are situations where the constant may not work perfectly, too (large temp changes, etc. - that may apply here).

 

[earthwormjim]

Well, the constants are calculated from continuous trips, so they are somewhat relevant. They are just predictive shortcuts which tell you what you will get for a given continuous trip. Essentially, they're exactly the same thing as your continuous single trip datapoint.



90% discharge is 40.3kWh. So this implies you used 40.3kWh/209Wh/rmi = 193 rated miles on that trip segment.

So this further implies your 100% charge (at that time) was: 193rmi / 0.9 = 214 rated miles

It doesn't work out exactly but there is rounding error (since you were using energy display), and any losses while in park would bias you towards a low estimate. (Say you lost a couple miles after disconnecting before you started driving, and furthermore due to rounding error you actually were closer to 89% used - that would mean (193+2)/0.89 = 219 rated miles.) In any case, the constant works out super close, even with these potential error sources. There are situations where the constant may not work perfectly, too (large temp changes, etc. - that may apply here).

Correct about the rounding error, that's why I assumed 89% battery used as the optimal case for my battery capacity. User cannot tell if the state of charge is at 99.5% or 100%. Same with whether the battery was at 10%, 9.5% or 10.49%, any number in that range is rounded to 10%. You can sort of eye ball it on the trip consumption graph, but not very precisely.

219 is very close to the stated range at 100% before I did that trip, the stated range was 220 miles, so we're on the same page. You're using the constants as sanity checks, makes more sense now.

 

[earthwormjim]

I took some pictures of the rated line with estimated distance, and distance displayed in miles on my range bar.

The constant for consumption in my SR+ is not 209wh/mi, nor 215wh/mi. It seems to be right at 219wh/mi.

It seems the constant did change with V10, and it explains my "lost" battery capacity. I didn't lose any at all, 227 mi at 219wh/mi yields 237 mi at 209wh/mi. Well within the margin of error for 240 mi initial range.

Well that seems pretty screwed up, changing the constant. Doesn't functionally matter, but makes the car look like it has battery degradation when it doesn't. Certainly doesn't help with resale.

 

[AlanSubie4Life]

The constant for consumption in my SR+ is not 209wh/mi, nor 215wh/mi. It seems to be right at 219wh/mi.

Next time, do a drive of 5 miles at a consistent consumption so the scale is readable.

This plot shows the constant above 219Wh/rmi. If you zoom in (by limiting the range of efficiency shown) you will see it is about 5Wh/rmi higher. Another way is to drive at ~224Wh/mi and show the line disappears (they lie on top of one another).

capacity. I didn't lose any at all, 227 mi at 219wh/mi yields 237 mi at 209wh/mi. Well within the margin of error for 240 mi initial range.

Remember your discharge constant is still 209Wh/rmi.

Well that seems pretty screwed up, changing the constant.

There is no evidence the constant has changed. The line at around 224Wh/rmi would make it completely consistent with other vehicles. There is always an offset of ~5Wh/rmi from the value used for calculation on this graph.

For a long time now, the constant on this screen used for the calculations has been 219Wh/rmi. You can see that is still the case (rated and projected are the same), even though the “rated” line is not at 219Wh/rmi.

 

[earthwormjim]

Remember your discharge constant is still 209Wh/rmi.

That still makes zero sense. The car is calculating range with some number that appears to be right at 219 wh/mi (or +5wh/mi as you say). Which my screenshot shows. 220wh/mi on the display subtracts 1 mile of range more than the range indicator does.

How is the constant some how 209wh/mi? I drove at 209wh/mi too, it had way more range than indicated.

 

[AlanSubie4Life]

How is the constant some how 209wh/mi?

Who knows. You can measure it. It is very repeatable. It is just a trip meter. It does not have to have an accurate scale or a scale that matches other scales. It is a bit confusing since this makes the projection wrong, though.

That still makes zero sense.

Agreed. Does not mean it is not true.

The car is calculating range with some number that appears to be right at 219 wh/mi (or +5wh/mi as you say).

It is using 219Wh/rmi. The line is at close to 224Wh/rmi. You can verify this.

No constants have changed as far as I can tell.

 

[earthwormjim]

Who knows. You can measure it. It is very repeatable.



Agreed. Does not mean it is not true.



It is using 219Wh/rmi. The line is at close to 224Wh/rmi. You can verify this.

OK I think you need to clarify. You just said the discharge constant is 209wh/mi, but then you said the car is using 219wh/mi.

How can the constant be 209wh/mi if the car never uses 209wh/mi to calculate anything?

Or is it 209wh/mi if I have zero regen braking and just coast along? So the 219wh/mi constant takes into account regenerative braking losses, since it won't capture 100% of the energy you wasted accelerating? Basically it requires 219wh (or more?) of regen braking energy to get 1 mile of range back on the graph if it goes below 0 on the y-axis?

 

[AlanSubie4Life]

OK I think you need to clarify. You just said the discharge constant is 209wh/mi, but then you said the car is using 219wh/mi.

How can the constant be 209wh/mi if the car never uses 209wh/mi to calculate anything?

Or is it 209wh/mi if I have zero regen braking and just coast along? So the 219wh/mi constant takes into account regenerative braking losses, since it won't capture 100% of the energy you wasted accelerating? Basically it requires 219wh of regen braking energy to get 1 mile of range back on the graph if it goes below 0 on the y-axis?

See my other posts. I think in this thread I had the summary but if not look at recent posts, one from last night. There are two constants: charging and discharging.

Charging constant converts added kWh to added miles. 219Wh/rmi.
For some reason this is also used for the range estimation graph projected range. Yes, it would make more sense to use the discharge constant.

Discharge constant: 209 Wh/rmi. To first order there is no dependence on regen or consumption level. You can do a lot of regen on a drive and calculate 209Wh/rmi, or no regen and calculate 209Wh/rmi.

This constant converts trip meter used kWh to rated miles used.

To calculate the constant, measure kWh used and rated miles used for a long drive, and divide the two.

And then there is the rated line on the consumption graph which is at ~224Wh/rmi.

 

[earthwormjim]

But how does 219wh/mi yield identical projected range as the rated miles displayed range? Both numbers are 197 miles in the display on my screenshot.

Or are you saying that even the rated miles display is also using 219wh/mi for its displayed number? But the rate that the miles on the display are decremented is at 209wh/mi?

 

[AlanSubie4Life]

But how does 219wh/mi yield identical projected range as the rated miles displayed range? Both numbers are 197 miles in the display on my screenshot.

Or are you saying that even the rated miles display is also using 219wh/mi for its displayed number? But the rate that the miles on the display are decremented is at 209wh/mi?

Easiest to use your specific example that you took a picture of. Your 197 rated miles, if you drive at the efficiency of 219Wh/mi, will allow you to drive:

197rmi*209Wh/rmi / 219Wh/mi = 188 miles.

Note the Energy Consumption projected range is 197 miles if you drive at 219Wh/mi (which is wrong since it uses 219Wh/rmi as the constant).

Incidentally, I can tell from your picture that you had ~225 rated miles at 7:42PM. This calculation is done using the 209Wh/rmi constant.

23.7mi*246Wh/mi / 209Wh/rmi = 27.9 rmi

197rmi + 28rmi = 225rmi.

Note if you tried to use 219Wh/rmi you get 223.6 rated miles as your starting point (this is too short a drive to really be able to see which is the correct value to use - but you tell me what the correct answer is...).

 

[earthwormjim]

Easiest to use your specific example that you took a picture of. Your 197 rated miles, if you drive at the efficiency of 219Wh/mi, will allow you to drive:

197rmi*209Wh/rmi / 219Wh/mi = 188 miles.

Note the Energy Consumption projected range is 197 miles if you drive at 219Wh/mi (which is wrong since it uses 219Wh/rmi as the constant).

Incidentally, I can tell from your picture that you had ~225 rated miles at 7:42PM. This calculation is done using the 209Wh/rmi constant.

23.7mi*246Wh/mi / 209Wh/rmi = 27.9 rmi

197rmi + 28rmi = 225rmi.

Note if you tried to use 219Wh/rmi you get 223.6 rated miles as your starting point (this is too short a drive to really be able to see which is the correct value to use - but you tell me what the correct answer is...).

226 miles of range when I left, so I'm seeing where the math is coming from, that makes a lot more sense, thank you.

Still begs the question, why they have different charge and discharge rates for the rated miles display?

With 209wh/mi discharge rate, my car is practically right where it should be when full, roughly 237-240 miles of range. But since it charges at a rate of 219wh/mi, the car displays 227 miles when full. How is that system beneficial to the user?

 

[AlanSubie4Life]

Still begs the question, why they have different charge and discharge rates for the rated miles display?

Tesla works in mysterious ways.

With 209wh/mi discharge rate, my car is practically right where it should be when full, roughly 237-240 miles of range. But since it charges at a rate of 219wh/mi, the car displays 227 miles when full. How is that system beneficial to the user?

Not sure if I follow you here...your car has 227 rated miles which means you can drive 227 rated miles at 209Wh/mi, on the trip meter.

If the charging event energy of 227rmi*219Wh/rmi actually were all available for use on the trip meter, you could do 237 miles @ 209Wh/rmi (227rmi*219Wh/rmi/209Wh/mi). But that is not how it works.

 

[earthwormjim]

Tesla works in mysterious ways.



Not sure if I follow you here...your car has 227 rated miles which means you can drive 227 rated miles at 209Wh/mi, on the trip meter.

If the charging event energy of 227rmi*219Wh/rmi actually were all available for use on the trip meter, you could do 237 miles @ 209Wh/rmi (227rmi*219Wh/rmi/209Wh/mi). But that is not how it works.

What I wrote doesn't make sense when I re-read it...
And the car was at 226 when I left, I don't know why I keep putting 227 in there.

What I was trying to say, was that I charged the car with 226 mi * 219wh/mi = 49494 wh of energy. 49494 wh of energy at 209 wh/mi should yield 236.5 mi of rated discharge range though right? Or the displayed rated range after you have just charge the car, always uses the energy in the battery divided by 209wh/mi? So there was 226 mi * 209wh/mi = 47234 wh of energy in the battery when I left after charging?

Is it theoretically 47234 wh or 49494 wh?

Edit, now that I think about it, a slightly higher charge constant allows Tesla to subtly charge more for electricity at supercharging stations, possibly to help account for charging efficiency losses?

 

[AlanSubie4Life]

Or the displayed rated range after you have just charge the car, always uses the energy in the battery times 209wh/mi?

The displayed rated range may as well be the energy in the battery divided by 209Wh/rmi, in terms of interpreting it for what it means on the trip meter. But then there is the question of what “energy” value to use there. So:

Is it theoretically 47234 wh or 49494 wh?

Theoretically adding 49500Wh to the battery on the charging screen means that you can take out (only) 47200Wh on the discharge screen.

So add 49.5kWh. Gives you 47.2kWh available which is 47.2kWh/209Wh/rmi = 226 rated miles.