Tesla 3 SR+ vs. Leaf Plus Battery Capacity

Board,

Quick question regarding the EPA testing of the Plus and the 3 SR+. When looking at the comparative findings, I am a bit confused between the listed "Energy Capacity" and the kilowatts charged.

The Leaf Plus is shown with an Energy Capacity of 176 (no Units on the line)
The Tesla 3 SR+ is shown with an Energy Capacity of 230

Leaf Plus Battery Specific Energy: 140.9
SR+ Battery Specific Energy: 150
(Page 3 of each pdf)

On the face value, this would seem to imply that the SR+ has a larger battery.

Lower in the report, on the recharge, it showed:
Leaf Plus recharge of: 68.3 KW
SR+ recharge of: 62 KW

Both I assume are wall figures, so subtracting 10% would give you the ~61KW usable in the Leaf and ~55KW usable in the Tesla (as is widely reported).

So the question is why the higher energy capacity showing higher on the Tesla. Is that because it is electronically limiting the capacity available?

Leaf Report:
https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=46941&flag=1

SR+ Report:
https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=46968&flag=1

While I love my Leaf+, It is interesting to see that the Dyno tests for the SR+ are higher then Leaf. Test weight is significantly higher in the Leaf than the SR+ which likely accounts for much of that difference, given these tests are sans drag. (Test weight of 4250 for the Leaf vs. 3875 for the Tesla). The difference is about 10% for both weight and dyno distance.

Does any one have comment/understanding in the different battery measures as to why they differ?

Interesting for sure and probably above my present knowledge level.

Real world range I’m not sure though. There are a couple folks near us that have the model 3 SR plus. Even in warm conditions their range numbers are less than what they expected. When it gets cool out the heat pump in the Leaf will give an advantage over the Tesla. The one person I have talked to with a Leaf Eplus is seeing pretty impressive range in the same conditions. It’ll be interesting to watch.

Interestingly enough, the Chevy Bolt and Leaf have almost identical Energy Capacity values.

The term was changed in EPA literature to Nameplate Battery Charge Capacity.

2.20. Nameplate battery charge capacity is the capacity, claimed by the battery manufacturer on
a label or in instructions, that the battery can store, usually given in ampere-hours (Ah) or
milliampere-hours (mAh) and typically printed on the label of the battery itself. If there are
multiple batteries that are connected in parallel, the nameplate battery charge capacity of the
batteries is the total charge capacity of the parallel configuration, that is, the nameplate charge
capacity of each battery multiplied by the number of batteries connected in parallel. Connecting
multiple batteries in series does not affect the nameplate charge capacity.

2.21. Nameplate battery energy capacity means the product (in watts-hours (Wh)) of the
nameplate battery voltage and the nameplate battery charge capacity.

This would seem to imply Tesla's battery is significantly larger then what its charging to. (Allowing a 55kWh charge but has capacity for 75 or something...offer to expand later maybe?)

DougWantsALeaf said:

Leaf Plus Battery Specific Energy: 140.9
SR+ Battery Specific Energy: 150
(Page 3 of each pdf)

On the face value, this would seem to imply that the SR+ has a larger battery.

Click to expand...

No such conclusion is implied.
Specific energy is Wh/Kg

----------------
Please learn the difference between kW (power) and kWh (energy)

Got it. Thanks for the clarification.

As an aside, the specific energy values of the packs are interesting because they are so close even though the LEAF does not have a cooling mechanism.

I am also curious regarding what special sauce Tesla uses to achieve about a 10% (367 vs. 337) UDDS charge depleting test vs. the leaf considering its just dynamo.

Also interesting that the highway depleting Tesla 3 test also was only 10% less then the charge depleting test. (335 miles vs. 367) . The leaf lost over 15%, at 280 vs. 337. Hats off to both efficiency measures for Tesla. It supports the 240 range EPA vs. 226/215 for the Leaf in terms of comparative range. The older Tesla's had much lower efficiency, which is why I think the X drivers I know (or those that own X and 3) report ranges much lower then what would expect on a 75kWh battery.

What I can't line up are the reviews saying the Tesla under performs the 240 EPA rating. The UDDS tests seem to support that they should be about right. Tesla drivers have a heavy foot?

The reviews are neither controlled conditions or a head to head comparison. Any conclusions they care to draw about range are suspect.

However, physics tells us that the Tesla Model 3 will outperform the LEAF in highway range by more than the EPA test ratios due to a quirk in the EPA method: the highway test is actually a low-ish speed test that is 'corrected' to normative USA driving speeds by applying a 30% discount to approximate 65 mph speeds.

This works OK when the cars have average fleet CdA values but the Model 3 stands out by having an exceptionally low CdA. The LEAF is ~ average. The higher the actual driving speed over ~ 60 mph, the more the Model 3 will outperform the LEAF. My personal experience over a year of ownership is 225 Wh/mile at 65 mph and ~ "EPA" (237 Wh/mile) at 70 mph. Those results are confirmed over almost 20k miles of driving although they have to be interpreted in the context of my car use at 5,000 - 7,000 elevation above sea level.

FWIW, this discussion is academic. In the real world the Model 3 owner drives as fast and as far as they care to by relying on the Supercharger network. Bjorn Nyland just posted a video on youtube where he drove a Porsche 911 and his friend drove a Tesla Model 3 performance in a friendly 800 km r/t race. This was on regular Norwegian roads and I do not think they broke any laws. The Model 3 *won.* That might seem impossible without cheating but it actually just points out what Tesla Model 3 owners know: the car waits for them at stops, not the other way around. Bjorn took one too many bathroom breaks

DougWantsALeaf said:

Test weight is significantly higher in the Leaf than the SR+ which likely accounts for much of that difference, given these tests are sans drag.

Click to expand...

Not so.

Drag is programmed into the dyno from coast-down testing. The difference in CdA between the cars is the lion's share of the difference in efficiency during the "highway" testing. The mass difference adds mass*g*RR Newtons of resistance, or about 8.82 N per 100 Kg mass difference. That works out to 3.94 Wh/mile per 100 Kg.

Thanks for the responses.

Thank you for the info regarding the dyno test. I had thought for wind resistance, it was a flat .7 multiplier. I didn’t know it was programmed into the dyno.

That also makes sense as city speeds (<35) see much more parity between the cars.

Beyond the Tesla boards I am on, Alex on Autos also did a 4 car comparison, suggesting an overstatement of the SR+ range. As you mention, on those same Tesla boards, many have other in line or better to epa range experiences as well. The test while not absolutely controlled, did use heat and factors which play with overall range.

DougWantsALeaf said:

I didn’t know it was programmed into the dyno..

Click to expand...

Somewhere in that EPA document you will come across friction coefficients A, B and C for a second order polynomial equation. Plot that equation to see the modeled combined air and road drag for the car*. The coefficients are derived from the coast down test.

There is rampant misunderstanding and misinformation surrounding the dyno test. It is present to measure those variables not counted in a coast down, namely things like braking and acceleration related drivetrain losses and the transmission.

It is a useful exercise to think about how 'real world' driving MAY differ from EPA results:
1. The car is driven at a speed different than the EPA test. As I mentioned earlier, the discounted highway result is ~ 65 mph in a car with average CdA
2. External wind
3. A/C use different than the EPA presumption
4. Road surface conditions different than those present during the EPA coast-down. They use dry tarmac in fair condition.
5. Ambient temps. EPA testing is ~ 20C

It is tempting to try and match the coefficients to zero through second order energy consumption rates in the car but don't bother; the coefficients are simply a best fit for the data. Only the second order coefficient is reasonably close to Aero drag. Oh, and remember that the numbers are American units of measurement (bleh.)

* I've wondered before about the state of the car during the coast-down but I do not have a definitive answer yet, and I don't know how an EV is handled. I *think* that an ICE car is IG-ON and placed in neutral.

In those EPA tests the total road load for the Leaf, Niro, M3 SR+ is quite interesting. Its 12.7 for the leaf, 10.8 for the Niro, and 9.5 for the M3 SR+. That's nearly a 30% penalty for the leaf.

The capacity difference between Leaf and Niro looks to be about 2.5 kWr, so that might explain about a 10 mile difference in range between the cars...so 239 - 10 = 229 which is only 1.5% different from the Leaf 226.

The SR+ does appear to have about 6kWh less capacity, or about a 55kWh pack.

Given the Niro and Leaf have the same coefficient of drag, I am a bit surprised at the difference. I sill don't claim to understand the 3 components (and why Niro has negative number in one of the values).
Niro: https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=45390&flag=1

Its also interesting that it looks like Nissan sent in the Leaf for one more trial with the battery opened up a little:

https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=46723&flag=1 (here the recharge is 70kWh)

vs. the other tests:

https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=46941&flag=1 (Which show a 68.3kWh recharge).

The extra power didn't add much to the overall range, 8 miles on the City test.


All that said, I am finding the key to long range on the highway for the leaf is a very steady foot. Reduce power fluctuations and let speed fluctuation up and down a bit, like the old leaf.

I would like to see a side by side 55 MPH drive from full to exhaustion between Leaf, Niro, and SR+ on a relatively flat course.

CoD is only half of the equation. You also need the Cross Sectional Area to calculate the actual drag value. Beyond that you still need to calculate the additional drag from turbulence under the car. The EPA runs the test on a dyno-meter and just estimates a drag value. Their numbers are not accurate representations and they admit that. I have never seen any manufacturer publish the CSA values or total drag values. A run down test could give a good estimate if properly done. A better choice for an EV would be voltage and current draw on a level surface at a constant speed. Even better would be to do it at several speeds and build a power curve. Absent that, a large sample of owner supplied power used over distances could be used. Real world data rules every time.

SR 3+ owner here.

Very recently completed a road trip with the family of 4, loaded car, about 1200 miles round trip NorCal to SoCal and back. We achieved very close numbers to SageBrush (~225 Wh/mile at 65 mph and ~ "EPA" [237 Wh/mile] at 70 mph).

4.5 miles/kWh is pretty consistent to what I can get on North-South Routes at about 65. Routes going directly West have cut into my efficiency due to headwinds. At 70, it’s been 250-270 wh, which is understandable given the higher coefficient of drag.