A senior tesla executive's comforting answer to concerns re: "loss of range"

[martinwinlow]

Blimey! Enough flannel already! Can someone who has an S with apparent range reduction *please* just go out and see if they can do 20, 30, 40 miles or whatever past zero and prove Mr Guillen's theory is correct… or not? Thank you!

 

[brianman]

Since all the firmware updates, algorithm / balancing debates, I've been less concerned about what the rated range number is, and more concerned about exactly this - how many miles I'm actually getting on a charge and the average Wh/mi.

+1 for still missing the projected range option for the instrument cluster

- - - Updated - - -

My wife's CRV.

My other car lists range to empty in miles (or km) as well.

 

[WarpedOne]

My wife's CRV.

I left out "correctly".

 

[Baiao]

Latest firmware update shows my Model S at 135 rated range from 126 !!

 

[ElSupreme]

Not sure I understand why measurement is so hard. We measure everything else. In line ammeters are common and pretty straight forward in current measurement. Voltmeters can easily measure voltage levels. I don't see why a basic software app couldn't give us something. Not trying to be augmentative, just don't see the problem. And it would satisfy a portion of owners wanting something other than changing range guesses. Given Tesla's repeated assurance that nothing is really changing, they must have something they are basing this on. Exactly what are they basing these claims on?

Here is a quick read. To determine a SOC of a battery you typically use two methods. Voltage reading (which is subject to changed based on discharge rate, and temperature among others). And coulomb counting which adds up all the current leaving the batteries. Both have issues. Voltage is variable based on conditions. Coulomb counting has long term drift if '0%' and '100%' are not hit every now and then to recalibrate.

http://en.wikipedia.org/wiki/State_Of_Charge#Voltage_method
State of charge - Wikipedia, the free encyclopedia

The 'Kalman Method' is using both of the above and monitoring other outside environmental affects and compensating for them. Tesla has likely just changed their formula to be more accurate after having much more data. But these calculations can only be as good as their instrumentation. And there will always be some error.

What you are suggesting is exactly what they are doing. But determining the actual state of the cells, much less the collective of the cells, are a bit finicky and thus hard to nail down to such precision.

 

[ThosEM]

The best way to determine out how much farther you can go at any moment is the touchscreen Energy app, with its projected range based on adjustably averaged recent consumption.

The rated range is evidently a number proportional to estimated battery state of charge in energy units (with a secret offset at the low end to create a "reserve"). The constant of proportionality is the rated consumption, which I make at 302 Wh/mi, or 188 Wh/km, after subtracting from 85 kWh an untouchable reserve of about 5 kWh set aside to preclude "bricking". So you can estimate the energy in kWh as remaining rated range divided by ~3.3 in miles or ~5.1 in km.

And now with software 5.9, we have a "blue" rated range component that can't be used until the battery is warmed sufficiently. That will be interesting to track at low SOC next winter when cold weather returns...

 

[Kraken]

No.. The best way you can find out how far you can go is to fully range charge and then hop in i-80 in Kansas and just drive 55 until your car stops.

 

[mknox]

All this discussion brings up a real puzzler: why is it easy for some people to get Wh/mi consumption below 300, and for others it is impossible? I just drove about 80 mostly highway miles this evening at 296 Wh/mi; and I wasn't even trying, with speeds of 65-80 over much of the distance.

Same here. Even at 32 degrees, on my 80 mile round trip commute I come in at under 300. It's mostly freeway and I'm driving normally, HVAC not on Range etc. In the summer, I can see "Since Last Charge" numbers for this trip as low as 260. I actually was wondering if my reduction in rated range was being made up on the other end with these unusually good efficiency numbers in the algorithm somehow.

 

[jerry33]

All this discussion brings up a real puzzler: why is it easy for some people to get Wh/mi consumption below 300, and for others it is impossible?

Alignment
Tire type
Tire pressures
Road surface
Weather and Temperature
Traffic
Driving style
Terrain
Practice (a lot of practice)

 

[Kraken]

Possibly even smaller factors: radio volume, which apps you leave open (I could see displaying the camera using more), which radio source you are using, brightness/night mode, seat heaters, kids seats (weight), stop and go traffic vs highway, speed, total passenger weight, regen. Some aren't much, but it all adds up.

In my p85+ i can get 300 easily by doing 55-60 on a highway, but as soon as I'm at 65-75 I'm 330-370.

side note: is this the week tesla decided to solve almost all of our biggest issues on the forum? Decreasing rated range, no auto lowering, fire issues... Were knocking them out now... Some of our longest threads might be obsolete soon.

 

[Super Gizmo]

Possibly even smaller factors: radio volume, which apps you leave open (I could see displaying the camera using more), which radio source you are using, brightness/night mode, seat heaters, kids seats (weight), stop and go traffic vs highway, speed, total passenger weight, regen. Some aren't much, but it all adds up.

In my p85+ i can get 300 easily by doing 55-60 on a highway, but as soon as I'm at 65-75 I'm 330-370.

side note: is this the week tesla decided to solve almost all of our biggest issues on the forum? Decreasing rated range, no auto lowering, fire issues... Were knocking them out now... Some of our longest threads might be obsolete soon.

Isn't that wonderful!!!!

 

[tomas]

A battery charging limitation still out there. That's the biggest one because costs $$ to solve.

 

[digitaltim]

As an EE, I have always assumed some method of coulomb counting was going on since voltage methods are difficult with Li-ion. This article is worth a read:

Hearst Article

I have some IEEE related links I can post but they get pretty technical.

 

[stevezzzz]

No.. The best way you can find out how far you can go is to fully range charge and then hop in i-80 in Kansas and just drive 55 until your car stops.

The mythical I-80 in Kansas, or the actual I-70? :biggrin:

By the way, I've driven I-70 through Kansas in my S and it's got way too much elevation change to be a good test: you descend almost 3000' from Goodland to KC.

 

[Chris Naps]

Finally an official statement!

 

[tomas]

The mythical I-80 in Kansas, or the actual I-70? :biggrin:

By the way, I've driven I-70 through Kansas in my S and it's got way too much elevation change to be a good test: you descend almost 3000' from Goodland to KC.

There's that Kansas stereotype at work! Isn't the flattest state Florida?

 

[Kraken]

There's that Kansas stereotype at work! Isn't the flattest state Florida?

Yeah... but there's too much traffic there.

Yeah, I-80 is probably Nebraska, I didn't bother looking at a map and just took a stab at it.

 

[AmpedRealtor]

All this discussion brings up a real puzzler: why is it easy for some people to get Wh/mi consumption below 300, and for others it is impossible? I just drove about 80 mostly highway miles this evening at 296 Wh/mi; and I wasn't even trying, with speeds of 65-80 over much of the distance. My lifetime average through two winters and a summer is 313 Wh/mi.

Here's what I think I know about what makes these numbers possible:

- 19" wheels, S85
- 5000'+ elevation (lower air density means less aero drag)
- reasonably level terrain except when I drive up into the mountains.
- moderate climate; low average wind speed.

BTW, my Rated miles remaining equals Projected Average miles remaining when the average consumption reads 302-303 Wh/mi. Some others have reported that they have to get consumption down into the 280's before this is true for them.

I'm in the Phoenix area where the terrain is largely flat. I drive a combination of freeway (70 MPH average) and city streets (5 MPH over limit average). My lifetime consumption is 290 Wh/mi. Most of my trips are in the 280-290 Wh/mi range.

P85
19" wheels w/ Primacy tires (3% range boost)
500'-1,000' elevation

I don't even have to try to hit those numbers. If I drive with a focus on efficiency, I can get the numbers below 270 Wh/mi.

I recently drove a S85 loaner w/ 21" wheels and I could not get that car under 305-310 Wh/mi. I think the type of tires, wheel size, tire inflation and the quality of your alignment make all the difference in the world.

 

[ecarfan]

I'm on 5.9. Have an S85 with out 6K miles on it. Compared to 5.8 I have seen a slight improvement in rated range. When I first got 5.9 I noticed that after charging to 90% I got 233-234 instead of the usual 230. Then two days ago I did a range charge and got the same 265 mile range I've always had, but what was interesting was that the next day I got 237 miles of range after a 90% charge. That is the highest I have ever had at 90%.

 

[Dave EV]

Possibly even smaller factors: radio volume, which apps you leave open (I could see displaying the camera using more), which radio source you are using, brightness/night mode, seat heaters.

All of these items are not likely to affect power draw by more than 25-100W at most, which is negligible compared to the amount of energy required to move a car down the road.

If any of those things requires more than 100W, it is poorly designed and should be fixed.