Only 265 mile range on 85 kWh battery?

[smorgasbord]

Then they recharge it using an AC source and measure how much electricity was consumed.

First, thanks for all the good EPA info in this and other threads.

In last week's Investor Call, Elon mentioned that he expected to get the MPGe rating up from 89 by improving the charging unit's efficiency. From the procedure stopcrazypp described, electricity used to cool the battery or lost via heat in the charging unit counts against the MPGe.

 

[AnOutsider]

Not totally true... we do have the AC/heater and radio on... as well as the dash display and infotainment unit...which draw power, albeit small compared to the power consumed by the drivetrain while in motion...

Well, that's why I said significant. At that point we'd cut the engine and just had the radio going on aux power. I'd imagine in the Model S that probably also pulls from the smaller battery (12v?), and not the main, range-providing pack. Point is, we wouldn't have drained the model s sitting there for an hour.

 

[vfx]

Not totally true... we do have the AC/heater and radio on... as well as the dash display and infotainment unit...which draw power, albeit small compared to the power consumed by the drivetrain while in motion...

Just that with battery the size of Tesla's, it's much less of a concern most of the time.

 

[jomo25]

As a reference point, the Volt with max A/C draws 3.3kW. So, its interesting driving in the heat of Phoenix, some of your "savings" of driving at a slower, more EV-efficient speed are lost in energy consumed to keep you cool.

 

[Tommy]

First, thanks for all the good EPA info in this and other threads.

In last week's Investor Call, Elon mentioned that he expected to get the MPGe rating up from 89 by improving the charging unit's efficiency. From the procedure stopcrazypp described, electricity used to cool the battery or lost via heat in the charging unit counts against the MPGe.

The Tesla's spec web page mentions a maximum of 92% efficiency for the on-board charger. Solar inverters run as high as 97% efficiency converting DC to AC; I have no idea if the same efficiencies can be achieved going AC to DC; though I hope the 92% can be improved upon.

 

[jerry33]

As a reference point, the Volt with max A/C draws 3.3kW. So, its interesting driving in the heat of Phoenix, some of your "savings" of driving at a slower, more EV-efficient speed are lost in energy consumed to keep you cool.

So does the Prius' compressor. Here in Texas, it can use about 4 mpg. Last summer was pretty hot with many over-100 days. Here are my numbers:

DATE__________ODO____INC_____AVG
-- High temperatures start here
06/22/11____122606____643____67.7 (3.5)
07/17/11____123251____644____69.1 (3.4)
-- Flat tire here
08/10/11____123900____648____67.1 (3.5)
09/07/11____124533____633____70.2 (3.4)
-- 12V battery changed here
09/27/11____125180____647____70.6 (3.3)
10/18/11____125708____614____69.7 (3.4)
11/07/11____126389____594____68.6 (3.4)
-- Cold weather starts here

 

[Andrew Wolfe]

Neither the Leaf nor the Volt ever got 5-cycle testing done. Their numbers were 2-cycle numbers adjusted to a 5-cycle equivalent by multiplying by 70% (76% for the Volt).

Again I explain the multiplier in this post:
http://www.teslamotorsclub.com/showthread.php/8252-EPA-range/page2?p=131625&viewfull=1#post131625

The actual formula the EPA uses is actually more complicated, but 70% is a good approximation.

If you want the details about it, you can find it in the "2008 and Later, Derived 5-Cycle Calculation" in the page below:
http://webcache.googleusercontent.c...ycle+derived+formula&cd=3&hl=en&ct=clnk&gl=us

Starting in 2012 (which includes the Model S), using a derived 2-cycle number is no longer an option. That means Tesla has no choice but to run the actual 5-cycle tests.
http://www.caranddriver.com/feature...y-mpg-estimates-measuring-fuel-economy-page-2

Didn't the 2012 models need to be retested? Aren't these tests required every model year?

 

[Andrew Wolfe]

The Tesla's spec web page mentions a maximum of 92% efficiency for the on-board charger. Solar inverters run as high as 97% efficiency converting DC to AC; I have no idea if the same efficiencies can be achieved going AC to DC; though I hope the 92% can be improved upon.

I think that the 92% includes losses involved in the battery itself during charging.

 

[stopcrazypp]

Didn't the 2012 models need to be retested? Aren't these tests required every model year?

Don't know (only way to know is if their EPA numbers changed or with another FOIA request). I don't think their EPA stickers changed for 2012 though. Correction: the Volt went from 90mpge hwy to 93 mpge hwy and 93mpge to 94mpge combined, but nothing else changed (which is kind of weird; maybe the PHEV formula changed slightly or the rounding was done different). Nothing changed for the Leaf.

The EPA doesn't require car makers to retest every variant of a car (you have to retest only if there are differences in the motor and transmission), so they might not have had to retest every model year if there were no significant changes to the drivetrain.

The Model S is completely new for 2012 so there is no way they can get away with using the adjusted 2-cycle test results.

Volt numbers:
http://www.fueleconomy.gov/feg/noframes/31618.shtml
http://www.fueleconomy.gov/feg/noframes/30980.shtml

Leaf numbers:
http://www.fueleconomy.gov/feg/noframes/32154.shtml
http://www.fueleconomy.gov/feg/noframes/30979.shtml

 

[EVNow]

Neither the Leaf nor the Volt ever got 5-cycle testing done. Their numbers were 2-cycle numbers adjusted to a 5-cycle equivalent by multiplying by 70% (76% for the Volt).

Right. Unfortunately, EPA numbers don't allow us to do an apple-to-apple comparison in this case.

I expect S to get a lower miles/kWh number than Leaf, driven the same way.

 

[stopcrazypp]

Right. Unfortunately, EPA numbers don't allow us to do an apple-to-apple comparison in this case.

I expect S to get a lower miles/kWh number than Leaf, driven the same way.

smorgasbord mentioned 89MPGe for the Model S (vs 99MPGe for the Leaf) in last week's earnings call, so the Model S does already have a lower miles/kWh number. Tesla is working to squeeze a bit more charging efficiency out of the S's charger, but there will still be a decent gap in efficiency.

 

[Norbert]

smorgasbord mentioned 89MPGe for the Model S (vs 99MPGe for the Leaf) in last week's earnings call, so the Model S does already have a lower miles/kWh number. Tesla is working to squeeze a bit more charging efficiency out of the S's charger, but there will still be a decent gap in efficiency.

AFAIK miles/kWh is usually measured in regard to the content of a full charged battery (= 85 KWh for Model S, or 24 kWh for the Leaf), independent of charging efficiency. (unlike MPGe).

 

[Norbert]

I expect S to get a lower miles/kWh number than Leaf, driven the same way.

Because of the weight? That's just one factor.

 

[stopcrazypp]

AFAIK miles/kWh is usually measured in regard to the content of a full charged battery (= 85 KWh for Model S, or 24 kWh for the Leaf), independent of charging efficiency. (unlike MPGe).

Depends on if you are taking about EPA or unofficial measurements. As I explained in a previous comment, the EPA numbers (kWh/100 miles) factor in charging efficiency because it measure electricity consumed at the AC socket, not at the battery.

 

[Norbert]

Depends on if you are taking about EPA or unofficial measurements. As I explained in a previous comment, the EPA numbers (kWh/100 miles) factor in charging efficiency because it measure electricity consumed at the AC socket, not at the battery.

In the sense of the driving efficiency (non-EPA) that is mentioned in discussions, for example 300 Wh/mile, or, the other way around, 3.3 miles/kWh.

Or for statements/questions as in the title of this thread.

The number including charging, as from the EPA, is probably usually given in MPGe, as a unit of measurement.

The first is interesting for how far you can drive, abstracted from the battery size, and the efficiency of the power train, also in terms of how good a use it makes of the (expensive) battery. Whereas the second (the EPA's MPGe) is usually for cost calculations in terms of electricity cost, I think.

 

[Norbert]

The Leaf got 73 miles on the EPA 5-cycle test? And the Volt got 35?

Neither the Leaf nor the Volt ever got 5-cycle testing done. Their numbers were 2-cycle numbers adjusted to a 5-cycle equivalent by multiplying by 70% (76% for the Volt).

Would Nissan and/or GM have the option to get an actual 5-cycle test instead of using the adjusted numbers? If so, wouldn't they do so if they expected getting better numbers that the multiply-by-0.7 "5-cycle equivalent"?

Certainly, for as long as those numbers (73 miles for the Leaf and 35 miles for the Volt) are the only *known* EPA numbers, be they "equivalent" or "real" 5-cycle numbers , it doesn't makes sense to say the Model S gets "only 265 miles", if the ratio to 85 kWh is better than those numbers compared to 24 kWh and 16 kWh. The Model S still has the best ratio based on (expected) official numbers, and we don't have any better numbers than those.

I suppose whenever Nissan or GM introduce new versions with better (or just different) ranges, they'll need to get a "real" 5-cycle test, if they want to advertise better EPA numbers.

 

[Norbert]

I expect S to get a lower miles/kWh number than Leaf, driven the same way.

To some extent, it may be depend on the battery size you compare it to. The Model S with a 40 kWh pack (160 miles @55 mph) has a better ratio than the 85 kWh pack version (300 miles @55mph), surely due to the lower weight of the pack, 4.0 vs 3.5 miles/kWh. A question would be, which ratio would the Model S get with a hypothetical 24 kWh pack?

 

[tdelta1000]

The ever present factor in the Model S vs the Leaf is weight. The leaf is smaller therefore it is lighter in weight then the S. So again, I like the reported EPA numbers.

 

[stopcrazypp]

The ever present factor in the Model S vs the Leaf is weight. The leaf is smaller therefore it is lighter in weight then the S. So again, I like the reported EPA numbers.

Size matters a lot too. It means that even though the Cd of the Model S is excellent, the CdA is still likely higher than the Leaf's. It also means a higher heating/air con load. Plus the larger/sportier wheels and tires means higher rolling resistance.

 

[Norbert]

Size matters a lot too. It means that even though the Cd of the Model S is excellent, the CdA is still likely higher than the Leaf's. It also means a higher heating/air con load. Plus the larger/sportier wheels and tires means higher rolling resistance.

However Tom Saxon, who owns both Leaf and Roadster, came to the conclusion that the Roadster's 245 mile range (2-cycle test) would be equivalent to about 85 miles with the Leaf. Which would lead me to expect that the Leaf's 5-cycle test would be distinctly lower than 85 miles. And that's the only comparison we have, other than the official numbers, as far as I know.