Almost 15% range loss Model 3 Awd

[AlanSubie4Life]

In any case I'm starting to wonder if some of these discrepancies are explained by the difference in energy required to be added to bring about a given change in SoC and the amount of energy available in bringing about the same change in SoC in the opposite direction.

I tend to think not. What you say is of course true - you're going to lose energy in the act of charging and the act of discharging. But available motive energy from the battery should still be able to be measured. And in the EPA test, they measured this available energy (not for a very high power discharge though). And it was 79.2kWh for a vehicle with 4000 miles. For a higher power discharge, of course the available energy might be a little lower - but not by much. But the fact remains that they actually pulled 79.2kWh of energy from the battery and measured it outside of the battery (meaning that any losses internal to the battery were not counted, and this was available energy).

My hypothesis (yet to be proven with data; it could be wrong - but I have not seen data contradicting it yet) is that for unknown reasons Tesla makes the trip meter read low. Hopefully some time we'll be able to align the charging data with the CAN bus data to see the scaling factor there (if any). Then we should know the state of things.

 

[TMThree]

There is absolutely nothing wrong with driving 95 mph and AC on High it should have very little impact on degradation, but it could have some over the long haul (equating to more charge cycles).

No one said it had an impact on degradation, but it could have an impact on the car's calculation on estimated range.

Miles == Charge Cycles.

Not so simple. Charging from 40% to 50% 10 times is far less stressful than charging 0 to 100% once, even if you drive exactly the same number of miles in both situations.

Depth of discharge, how fast you charge, what temp you charge, how long you stay at high state of charge, are all factors of significance. Chalking it up to just how many miles you drive is too narrow a scope that it is practically incorrect.

 

[AlanSubie4Life]

No one said it had an impact on degradation, but it could have an impact on the car's calculation on estimated range.

Will have no appreciable impact on the battery range indicator. Obviously the energy page is a different beast.

Battery Constants Explanation

Someday one of the people who tracks the car should calculate the constant when using 1000+Wh/mi, just to see how wide a range the constant is actually constant over. I missed the opportunity when I autocrossed mine.

 

[mswlogo]

No one said it had an impact on degradation, but it could have an impact on the car's calculation on estimated range.
.

As folks have said over and over. Driving habits DO NOT AFFECT the charge level in your battery.

Charging habits can throw the calculation off. You can beat the hell out of it or drive like grandma it should report the same level for a full charge.

That’s what people are trying to assess. Degradation. Not their driving efficiency. If you want that, look at the Energy App or your wh/mi. Not how full your tank is.

 

[wbhokie]

I'm down to 245 miles at 90% after a year. Just wrote to Tesla about it.

 

[Max3]

I'm down to 245 miles at 90% after a year. Just wrote to Tesla about it.

Do you have a LR AWD?

 

[wbhokie]

Do you have a LR AWD?

Performance... but yes, that implies LR AWD

 

[diamond.g]

Performance... but yes, that implies LR AWD

As you get low in SoC does the % and expected miles remaining, line up? IE at 10% do you have 31 rated miles left or is the value lower?

 

[wbhokie]

As you get low in SoC does the % and expected miles remaining, line up? IE at 10% do you have 31 rated miles left or is the value lower?

I haven't taken it that low, nor have I tried any of the calibration techniques yet. You could just chalk all of it up to "the car is smart enough to know how I drive and adjusts miles accordingly" too, but I don't believe it does that. I just do my daily commute and charge it back.

 

[MOD220]

I ordered a M3 and cancelled, as I still have no idea what expected range is. I drive 40k miles a year, 80% highway, usually 70-80mph. 310 miles would work, but when I factor in degradion, cold weather 1/3 of the year, 19" wheels as the 18s are not an option for me, and not running battery to empty, I fear this is really a car closer to 200 miles of range at times, not 300. I can't afford the time of stopping mid day to charge, wish there was more clarity on all this!

 

[AlanSubie4Life]

I ordered a M3 and cancelled, as I still have no idea what expected range is. I drive 40k miles a year, 80% highway, usually 70-80mph. 310 miles would work, but when I factor in degradion, cold weather 1/3 of the year, 19" wheels as the 18s are not an option for me, and not running battery to empty, I fear this is really a car closer to 200 miles of range at times, not 300. I can't afford the time of stopping mid day to charge, wish there was more clarity on all this!

Not really what is being discussed here but yeah, probably not the car for you. In those conditions it is a 200-mile car (about 150 miles between Supercharger stops). Works fine with Superchargers if they are located where you need them - and they are not busy.

I thought it was pretty great on my road trip. Worked well.

 

[birjman]

I set up another appointment with the same SC. Another tech texted back saying that the EPA of the car is 310 and that the battery is performing as expected. I told him that I have the RWD and not AWD model and that I have charged to 325 before. He replied back saying that it is expected degradation (so, just in a matter of seconds, he went from EPA=310 to expected degradation). I asked him if he can confirm if the loss is indeed degradation or merely a calibration issues. He replied a few days later saying that the battery is holding 97.7% charge and released the appointment.

So, basically inconsistent answers from 3 Tesla people I have spoken with.

I have set up an appointment with a different SC. Let us see what snake oil they have in store at this location.

If your next SC is Orlando, good luck...it's definitely snake oil there. Different answer every time, usually morphs into some variation of "your driving habits do affect rated range" (I'm at 245 wh/mi lifetime lol). My 80% is at 232-233 fwiw - LR RWD as well.

 

[TeeEmCee]

Bjorn posted some analysis on this, looks like Tesla locked out some of the battery capacity:

 

[AlanSubie4Life]

Bjorn posted some analysis on this, looks like Tesla locked out some of the battery capacity:

I'm too lazy to look up his videos, but I'd be curious to see his video where he got 150Wh/km for the constant. I've always seen 144Wh/km (230Wh/mi), and that is since around March/April of this year. I'm not aware of it ever changing for the AWD (I think he was suggesting it did change at some point over the summer (see 17 minutes in), but it's hard to follow sometimes because there are a lot of words).

Maybe it changed before I started looking at it.

To be honest though, this constant stuff doesn't actually matter except for understanding how your rated miles tick off relative to the trip meter - the only way you can tell how much energy your battery actually holds is to measure it like they do in the EPA test. There's no reason the trip meter needs to be accurate. They could have changed the constant from 150 to 144, but also changed the scaling of the trip meter "kWh" by 4%. No way to know for sure, except to measure all of the energy coming out of the battery directly using calibrated equipment (not using the trip meter).

You can't use the charging event, due to the losses he describes, of course. Though you could use it (and carefully recorded historical data) to determine whether the scaling of the constant was real or just a change in meter scaling (which I think he did here, but it was hard to tell which two events he was comparing - whether the "before" event was from before he claims the constant got changed, specifically). In his Ionity data (corrected to 10-90%), it does suggest 2% energy scaling for a given amount of rated miles added to the car (62.2/65.6*499/483), but that's not 4% (144/150). And there are other factors there that could create that 2% difference during the charge event (temperature, etc.), and the correction from 5% start point to 10% start point could also introduce error, due to different losses during that time.

 

[BPeter]

Looks like the Model 3 is being hit with the capping similar to the S/X.
Huge thread in the S forum here: Sudden Loss Of Range With 2019.16.x Software

Althought according to Bjorn's video the cap on the Model 3's voltage is at the lower end vs the S on the top end. That means the BMS doesn't let it discharge below a certain voltage, that is now a higher voltage than it used to be. Whereas on the S the BMS is restricting the max voltage to 4.1V instead of the original 4.2V. Restricting the top voltage is also taking away maximum power which hurts acceleration.

 

[Max3]

UPDATE!!!

I scheduled a new SC appointment yesterday. Today I got an sms saying that they looked into my car and that the battery modules are unbalanced. I knew cells could be unbalanced but not whole modules, interesting.... Someone had this problem?

 

[AlanSubie4Life]

These are my 90% charge.

@diamond.g

Thanks for the detailed data. Spent a couple minutes looking at your data today.

TL;DR:

I believe the CAN bus kWh have a different scaling than the charging & discharging (trip meter) kWh, plus the numbers read back on the CAN include the buffer (added to them). So they have an offset and a scaling from what you see on the charge screen and the trip meter. Hopefully some more empirical readbacks can refute or verify this theory and verify the scaling constant.

I wonder if this third constant is only applicable to the AWD, since it's the only one that has the discharge/charge ratio of 93.9% (the other RWD vehicles have closer to a 95.3% ratio of these constants...which is close to the ratio of this "new" CAN bus constant to the AWD charge constant (235/245 = 95.9%)
-----

For AWD only:
Here's the way it works, as far as I can tell (also based on your conclusions):

fullkWhNom: Energy your battery would contain at 100% charge, including the buffer.

bufferkWh: Amount of buffer (energy below 0 rated miles, some of which may be usable - no idea).

remainingkWhNom/expectedremainkWh/idealremainkWh: All similar values, not sure how they are related. These are all current estimates of energy in battery including the buffer, though.

toChargeCompletekWh: remaining kWh to get to currently set charge level.

Since your battery is supposedly ~300 miles (I'll call it 301) at a full charge (for the following to be truly accurate, we'd have to know exactly what it was at your given charge level - doesn't have to be 100%, to know for sure), it looks to me like the INTERNAL (not the charging or discharging constant!) kWh/mi constant is:

(74kWh - 3.3kWh )/ 301rmi = 235Wh/rmi (CAN) (If your actual 100% was 300, then it would be 236Wh/rmi, so again we'd need to know exactly how many rated miles 90% was, in conjunction with a CAN read, to be really accurate about this constant).

Checking at the 90% level (using your picture):

66.9kWh + 0.2kWh (to get to 90%) = 67.1kWh (total energy including buffer)

67.1kWh - 3.3kWh (buffer) = 63.8kWh (above 0 rated miles)

63.8kWh/235Wh/rmi = 271.5 rated miles @ 90% => 301.6 rated miles at 100% (So seems close but not perfect)

(Fitting to your 54%/55% CAN bus data, I predict: 0.54*301rmi*235Wh/rmi +3300Wh = 41.5kWh (car read 41.1kWh...so that is a bit off...)...but it would be more helpful to get the rated miles (AND % displayed on the screen) in conjunction with future CAN bus readbacks)

Anyway, if you'd like to measure this - since you have the capability, you could, my suggestion would be:

1) Do a "warming" drive in your car to get it up to temperature.
2) Then charge to 90% and start driving right after it completes (so it is still warm).
3) Immediately prior to driving, change to distance and record rated miles (and %), and read back from CAN bus the kWh info
4) Do a reasonably long continuous drive (I'd recommend using at least 20kWh to help with accuracy, the more the better).
5) Turn OFF HVAC, then go to park, immediately take a picture of the trip meter Wh/mi and miles traveled. Also, immediately read back from the CAN bus the kWh info. And the rated miles remaining and % remaining (swap between energy and distance really quickly).

Predictions:
As an example (for your specific case of data above being captured for the case of 300 rated miles at 100%), I would expect to see the following for a 35kWh drive (as displayed on trip meter):

Start:
90% of 301 = 271 rated miles
fullkWhNom: 301rmi*235Wh/rmi + 3.3kWh = 74kWh
remainingkWhNom: 270.9rmi*235Wh/rmi + 3.3kWh = 67kWh

End:
35kWh (trip) * 235Wh/rmi (CAN) / 230Wh/rmi (trip) = 35.8kWh (CAN) used
35kWh (trip) / 230Wh/rmi (trip) = 152.2 rated miles used. So, 271rmi - 152.2rmi = 119 rated miles remaining (39/40%)
fullkWhNom: 74kWh
remainingkWhNom: 118.8rmi * 235Wh/rmi (CAN) + 3.3kWh = 31.2kWh

(Of course, this aligns with 67kWh (CAN) - 35.8kWh (CAN) = 31.2kWh )

So those are my predictions (just substitute your trip miles * Wh/mi for 35kWh above). If it doesn't work, then I'm wrong!

I can't work out the SOC reported numbers! To me, the only formula I could come up with that seems close at both points for "SOCmin" was:

(remainkWh - bufferkWh * (remainkWh - bufferkWh)/(fullkWh - bufferkWh) ) / (fullkWh - bufferkWh)

but can't make sense physically of the utility of that formula (it's kind of a "releasing buffer" definition where more of the buffer is available the lower your state of charge), and can't figure out any of the other SoC numbers.

The SOC on the screen has always appeared to be simply: (remainkWh - bufferkWh)/(fullkWh - bufferkWh)

 

[N54TT]

UPDATE!!!

I scheduled a new SC appointment yesterday. Today I got an sms saying that they looked into my car and that the battery modules are unbalanced. I knew cells could be unbalanced but not whole modules, interesting.... Someone had this problem?

That’s good to hear they finally acknowledged something is off. what are they going to do?

 

[ran349]

@diamond.g

fullkWhNom: Energy your battery would contain at 100% charge, including the buffer.

For the model S it works like this:
fullkWhNom/charge constant = rated miles.
For example, for a 100% charge of 301 rated miles, then the full pack would read 301 x .245 = 73.745 kWh, or displayed value of 73.7.

It might be different for the model 3 though, I haven't seen the data for those.

 

[AlanSubie4Life]

For the model S it works like this:
fullkWhNom/charge constant = rated miles.
For example, for a 100% charge of 301 rated miles, then the full pack would read 301 x .245 = 73.745 kWh, or displayed value of 73.7.

It might be different for the model 3 though, I haven't seen the data for those.

Numerically, that value seems to work out in this case (about 73.745-74kWh which is what was measured).

However, it seems like if that were the case, you'd expect, say, at 54% of your rated miles (a situation captured above), you'd use the formula:

remainingkWhNom = fullkWhNom * 0.54 = 40kWh (which is significantly different than what was captured).

So unless there is a different weird formula for remainingkWhNom, I'm not sure that the apparent match of fullkWhNom to the formula 301*0.245 is anything other than a coincidence.

Kind of need more datapoints with all the available information to know for sure what formula makes sense.

For that formula to hold, in any case, I'd expect that the size of the buffer reported by the CAN bus would have to be scaled proportionately to any battery degradation that occurs. Otherwise it would cease to align properly as the battery degraded. (In other words, the buffer would always need to be about 6.1% (1-230/245) of the full battery capacity.) Does not quite seem to align with the available data so far.