Capacity Loss on 2011-2012 LEAFs

[RegGuheert]

The Dyno I have is a DynoJet Dyno, which you can never over heat. basically its a 5000lb drum that is calibrated for size and wt, then calculates force of inertia. This spins freely so you can not adjust resistance, granted this is how the auto makers used to get fuel economy in the past and is less realistic than driving on a road. That said it can reproduce runs very consistently and thus show minor changes as it related to power. I think it would be fine to show energy used for distance traveled but I would not use that number for real world mileage. I may just check my car out to be able to gauge my distance now with recent 1 bar loss, and then again in a few months if someone wants to see weather changes. (hope I dont lose another bar) or I will show , distance lost when losing another bar.

O.K. Thanks for the details!

That's decent for measuring power and torque curves, but it would not be very useful to load a Nissan LEAF to drain the battery for a range test. It would work, but you would have so little loss that it might take a VERY long time to do it. I would definitely give it a try with your car first before getting a car from a dealer.

And, BTW, I don't think a LEAF from a dealer lot is a very good control, given how they treat those batteries some places.

 

[TonyWilliams]

Ok, you guys caught my mistake. I didn't think it was right, but my faulty math PROVED it !!!

 

[LEAFer]

Prediction: Dyno range at full charge (new battery with usable capacity of 21kWh) at constant 60mph, no CC: 137 miles.
:ugeek:

( Other details: 70F ambient and battery pack temp; no driver or passengers; no cargo; 40psi tires; run down to Turtle; no accessory (lights, radio, etc) use; no wind "simulation" or fans. )

 

[TonyWilliams]

4 miles at 250 watts is 1kWh consumed, and we have about 21 kWh to play with on a good day. 4 times 21 equals 84 mile range at 60 mph.

If 1 kwh is consumed in 4 minutes that would be about 15 kw by my calculation.

Too much editing!!!

4 miles at 250 watt/Hours per mile is 1kWh consumed per 4 minutes at 60 mph (15kW consumption, or 20 horsepower), and we have about 21 kWh to play with on a good day. 4 minutes multiplied by 21 kWh equals 84 mile range at 60 mph.

Of course, this would include the wind resistance going down a highway, if we're using a dyno. So, I'm with LEAFer..... 130-150 miles at 60mph instead of 84 miles.

 

[SanDust]

I don't know what the duty cycle is, but the LEAF at 60mph is consuming but about 250watt/Hours, or 1kWh per 4 minutes (60/4=15kW, or 20 horsepower).

4 miles at 250 watt/Hours is 1kWh consumed per 4 minutes, and we have about 21 kWh to play with on a good day. 4 minutes multiplied by 21 kWh equals 84 mile range at 60 mph.

So at 60 MPH the car is using 14.8 kW. Seems maybe a tiny bit low but certainly reasonable.

 

[Nekota]

I wouldn't waste any effort putting a fan on the battery; it's a sealed, slightly pressurized container that isn't getting much air circulation around normally driving down the highway (there's a big aerodynamic fairing covering the bottom of the car).

Tony, great write-up. Sound advice on the dynamometer, wanted to mention it as well, but you beat me to it.

I agree that it's not worth bothering blowing a fan at the front of the car, especially if it's a demo or a loaner. However, and in the name of science, you might want to try the following:

1. Remove the emergency shutoff hatch
2. Open your front windows an inch
3. Drive the Leaf at 35 mph or above (freeway speeds would be ideal)

I would be curious to know what your opinion of air circulation around the battery will be then. For what it's worth, I'm under the impression that most of the air is sucked into the cabin from the opening below the rear seat and it's unclear to me how much air, if any, is forced around the pack from the front of the vehicle.

I have a LEAF brochure from Japan that shows the air flow around the battery including the channel where the disconnect is. This appears to be likely since the bottom of the LEAF is closed and the intake air entering the grill and passing through the radiators has to exit somewhere and going under the car and around the battery on the way to the rear exit. I'll scan the page and edit this post with a link later tonight.

edit with link to battery with pink (I think airflow?)

https://docs.google.com/open?id=0B-80HTqdiCI3enh1LXRKNFdPWkE" onclick="window.open(this.href);return false;

 

[cwerdna]

The Dyno I have is a DynoJet Dyno, which you can never over heat. basically its a 5000lb drum that is calibrated for size and wt, then calculates force of inertia. This spins freely so you can not adjust resistance, granted this is how the auto makers used to get fuel economy in the past and is less realistic than driving on a road.

Ummm..... I can't speak to the brand and model of dyno used for EPA FE testing, but I bolded one part of your post. Are you saying that automakers don't use a dyno anymore?

If so, they sure seem to given all the links I've posted at http://priuschat.com/forums/other-cars/67235-car-driver-truth-about-epa-city-highway-mpg-estimates.html" onclick="window.open(this.href);return false;.

I think I'd still have a fan blowing on the Leaf (just as they normally do on ICEVs) as something might overheat from sustained highway "speeds" w/o proper airflow.

If it were up to me, I'd set the cruise control the max speed it would hold while safely "driving" on the dyno, just to make the test go by quicker. As I said, I'd think that driving on a dyno for an hour or more at 60 mph would be really boring!

 

[dsh]

Contacted via email and phone Director, Mark Perry of Nissan North America's Product Planning and Advanced Technology today, in addition to CEO Carlos Ghosn, Bill Krueger, and Colin Dodge. We will see what Mark has to say by September, as that is when they will start producing 200,000 LEAF lithium ion battery packs per year at their Smyrna, TN plant.

One can only hope and pray these execs. will keep their word and back their products up.

 

[surfingslovak]

I have a LEAF brochure from Japan that shows the air flow around the battery including the channel where the disconnect is. This appears to be likely since the bottom of the LEAF is closed and the intake air entering the grill and passing through the radiators has to exit somewhere and going under the car and around the battery on the way to the rear exit. I'll scan the page and edit this post with a link later tonight.

Awesome, thank you! This would answer a lot of questions :mrgreen:

 

[Boomer23]

I have a LEAF brochure from Japan that shows the air flow around the battery including the channel where the disconnect is. This appears to be likely since the bottom of the LEAF is closed and the intake air entering the grill and passing through the radiators has to exit somewhere and going under the car and around the battery on the way to the rear exit. I'll scan the page and edit this post with a link later tonight.

edit with link to battery with pink (I think airflow?)

https://docs.google.com/open?id=0B-80HTqdiCI3enh1LXRKNFdPWkE" onclick="window.open(this.href);return false;

Is there text that says that the pink is air flow?

 

[TonyWilliams]

That pink area is the structure that supports the battery in the car, isn't it?


Looking from the rear forward, underbody panels and rear diffuser removed:

Close up of left rear battery, looking forward.

 

[DaveEV]

Should have said:

I don't know what the duty cycle is, but the LEAF at 60mph is consuming but about 250watt/Hours, or 1kWh per 4 minutes (60/4=15kW, or 20 horsepower).

Technically, you should say either "about 250 Wh/mi" or "about 15 kW". Saying consumption is 250 Wh at 60 mph leaves distance/time as a variable...

The Dyno I have is a DynoJet Dyno, which you can never over heat. basically its a 5000lb drum that is calibrated for size and wt, then calculates force of inertia. This spins freely so you can not adjust resistance, granted this is how the auto makers used to get fuel economy in the past and is less realistic than driving on a road.

If the dyno only provides resistance by inertia, it will be useless for trying to measure capacity of the battery and only good for trying to measure power output of the car under acceleration. Unless you have one of the Eddy-Current DynoJet models you won't be able to measure battery capacity effectively using it.

 

[DaveinOlyWA]

I have a LEAF brochure from Japan that shows the air flow around the battery including the channel where the disconnect is. This appears to be likely since the bottom of the LEAF is closed and the intake air entering the grill and passing through the radiators has to exit somewhere and going under the car and around the battery on the way to the rear exit. I'll scan the page and edit this post with a link later tonight.

edit with link to battery with pink (I think airflow?)

https://docs.google.com/open?id=0B-80HTqdiCI3enh1LXRKNFdPWkE" onclick="window.open(this.href);return false;

Is there text that says that the pink is air flow?

my question exactly. if pink is airflow then that is a pretty large duct going across the middle there. hard to believe no one has seen that yet. Tony did a pretty detailed photo set of the underneath.

if it was air ducting, then the shape of it does not lend to an easy flow front to back (left to right) but then again, i am seeing light pink and dark pink and not sure what that represents

 

[TonyWilliams]

my question exactly. if pink is airflow then that is a pretty large duct going across the middle there. hard to believe no one has seen that yet. Tony did a pretty detailed photo set of the underneath.

if it was air ducting, then the shape of it does not lend to an easy flow front to back (left to right) but then again, i am seeing light pink and dark pink and not sure what that represents

Try and jam some air through here; battery charger cables, mid top of battery, looking from the rear, forward. Tubes are charger cooling lines:

 

[TonyWilliams]

No way is there ANY ductwork of ANY kind for air. Sorry.

 

[RegGuheert]

That pink area is the structure that supports the battery in the car, isn't it?

Yes. Here is an article in English which includes that picture: Why Did Nissan Develop an EV Battery?. It says:

Battery Protection Structure
Protects the battery through the frame of the car body.

FWIW, the article also says:

A battery that can control its heating without a cooling mechanism is also longer lasting, since the biggest cause of a battery's lifetime being shortened is overheating.

 

[mksE55]

Should have said:

I don't know what the duty cycle is, but the LEAF at 60mph is consuming but about 250watt/Hours, or 1kWh per 4 minutes (60/4=15kW, or 20 horsepower).

Technically, you should say either "about 250 Wh/mi" or "about 15 kW". Saying consumption is 250 Wh at 60 mph leaves distance/time as a variable...

The Dyno I have is a DynoJet Dyno, which you can never over heat. basically its a 5000lb drum that is calibrated for size and wt, then calculates force of inertia. This spins freely so you can not adjust resistance, granted this is how the auto makers used to get fuel economy in the past and is less realistic than driving on a road.

If the dyno only provides resistance by inertia, it will be useless for trying to measure capacity of the battery and only good for trying to measure power output of the car under acceleration. Unless you have one of the Eddy-Current DynoJet models you won't be able to measure battery capacity effectively using it.

That is why I stated it would not reflect real world distance. It would take alot of force to get it rolling but not as much to keep it going. It still requires energy to maintain the drum at a set speed but probably 80% or real world energy. It will be consistent on energy use. Just like if you turn you car on, then used TIME of AC use till empty. Anything that requires the car to use energy constantly will give you an amount to repeatedly Verify. If you have less X energy in your battery it will produce less Y product.

I am going over my setup. will use in car video to be able to capture bar loss, distance, LBW, VLBW over time with 10th of a sec. accuracy.

 

[RegGuheert]

I am going over my setup. will use in car video to be able to capture bar loss, distance, LBW, VLBW over time with 10th of a sec. accuracy.

Thanks! I'm looking forward to seeing your results!

I'll throw my prediction into the hat as well: Over 150 miles at 60 MPH on your treadmill. If I am correct, that means a 2.5 hour run! I would keep an eye on the battery temperature bars just to be safe.

 

[jspearman]

Mark me down as 2 bars lost. 14,180 miles. The band plays on.

 

[Stoaty]

Mark me down as 2 bars lost. 14,180 miles. The band plays on.

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