Nissan to Race All-Electric at Le Mans in 2014

[TomT]

Remember that the amount of power necessary to overcome drag goes up by the cube of the speed... 150 mph takes 27 times more power than 50 mph...

 

[LTLFTcomposite]

Remember that the amount of power necessary to overcome drag goes up by the cube of the speed... 150 mph takes 27 times more power than 50 mph...

But whatever the reasons, it doesn't take 27 times more gas. I'm guessing it doesn't take 27 times more electricity either, but have nothing to back that up.

 

[Nubo]

I need some enlightenment; is there a battery chemistry exist today that has ~10 times the energy density of LiFePO4 and conceivably be used for this Nissan Le Mans car? Not theoretically, since I don't think Nissan would make this announcement based theories, they must already know what they will be using. Have any lithium nano batteries been made that are large enough or have been applied to experimental EVs? Just wondering, I think that would be key for Nissan's success.

I wonder if that would be advantageous for Nissan, even if it existed. Far better publicity to use the technology they are producing, though probably a lot more modules... The exception might be if they had a new chemistry/technology that was on a definite track for production. Otherwise, they'd just be giving ammunition to the naysayers by using some lab experiment that had no relation to the EVs they are building for consumers.

 

[Drivesolo]

I wonder if that would be advantageous for Nissan, even if it existed. Far better publicity to use the technology they are producing, though probably a lot more modules... The exception might be if they had a new chemistry/technology that was on a definite track for production. Otherwise, they'd just be giving ammunition to the naysayers by using some lab experiment that had no relation to the EVs they are building for consumers.

Are you suggesting that they attempt to build a battery pack using the existing cells that they are using for the Leaf now? I think it's safe to say that it wouldn't work unless they are aiming to finishing dead last. The energy density is just not appropriate to be competitive w/ others in the field regardless of class. I agree w/ you that they risk doing more harm than good to the image of EVs unless they exhibit somewhat of a decent performance. IMO, anything other than a DNF or last place should would be viewed as positive by most. Lots of eyes are on the Garage 56 entry. The DeltaWing DNF-ed and even though it showed exceptional pace at Le Mans until its crash. It never got any real credit until it placed well at the Petit Le Mans.

 

[dgpcolorado]

Remember that the amount of power necessary to overcome drag goes up by the cube of the speed... 150 mph takes 27 times more power than 50 mph...

Power, yes. That battery is going to have to be able to produce a huge power output. But energy to overcome drag is the square of velocity because one of the "V"s cancels out, IIRC. So the energy storage requirements aren't so onerous.

 

[TonyWilliams]

Remember that the amount of power necessary to overcome drag goes up by the cube of the speed... 150 mph takes 27 times more power than 50 mph...

Power, yes. That battery is going to have to be able to produce a huge power output. But energy to overcome drag is the square of velocity because one of the "V"s cancels out, IIRC. So the energy storage requirements aren't so onerous.

I don't think I understand how it only takes twice the energy but three times the power. How exactly is that possible?

 

[DaveEV]

I don't think I understand how it only takes twice the energy but three times the power. How exactly is that possible?

You're traveling faster so you're covering more ground thus using power for less time. Energy = power * time.

 

[dgpcolorado]

I don't think I understand how it only takes twice the energy but three times the power. How exactly is that possible?

You're traveling faster so you're covering more ground thus using power for less time. Energy = power * time.

Yes, thank you drees. For an interesting intro to drag, including such concepts as "terminal velocity", I like this webpage: Aerodynamic Drag

 

[Nubo]

I wonder if that would be advantageous for Nissan, even if it existed. Far better publicity to use the technology they are producing, though probably a lot more modules... The exception might be if they had a new chemistry/technology that was on a definite track for production. Otherwise, they'd just be giving ammunition to the naysayers by using some lab experiment that had no relation to the EVs they are building for consumers.

Are you suggesting that they attempt to build a battery pack using the existing cells that they are using for the Leaf now?

Yeah, I think doing otherwise would tarnish their EV brand. With again, the exception being a battery that is slated for production -- not labware or vaporware.

I think it's safe to say that it wouldn't work unless they are aiming to finishing dead last. The energy density is just not appropriate to be competitive w/ others in the field regardless of class.

I'll leave the math to those more qualified. What if they used something like 3X the modules, allowed a greater percentage of SOC utilization, and went mad with Cd and regen? Perhaps an ultracapacitor buffer for the regen, which must be intense at the deceleration these cars undergo.

 

[Drivesolo]

I'll leave the math to those more qualified. What if they used something like 3X the modules, allowed a greater percentage of SOC utilization, and went mad with Cd and regen? Perhaps an ultracapacitor buffer for the regen, which must be intense at the deceleration these cars undergo.

3x as many modules will mean ~1200 lbs additional weight (assuming 1 Leaf batt was the standard to start off with), that's the weight half of a LMP1 car. Assuming the Nissan Garage 56 car would be equal to an LMP1 car it would have to haul around 50% more weight. Acceleration, braking, cornering all suffer. The need to have an even stronger and more rigid chassis and beefier suspension would compound the problem of weight. The additional weight would require more power to accelerate, which would cause capacity to take a further hit. When it comes to battery swapping attempting to swap a batt weighing nearly 1 ton is gonna make for some interesting pit stop albeit a very long one that will have to be done probably 2 times an hour if a vehicle like that were capable of being only a few seconds off of the race pace, 72kWh won't cover a decent race stint.

The CoD of a GT cars are horrible because of all the downforce they create, the only significant improvement over the past 20 years in their CoD has been in the DeltaWing. If there were some ways to improve the CoD and still have the same amount of downforce, it is already being applied. None of the teams that race at that level leave anything on the table and not apply it to their cars.

Ultracaps/Supercaps... dunno. Toyota's TS030 was using 'em for their GT cars. It's possible that Nissan might do the same.
http://www.roadandtrack.com/racing/insiders-look-at-the-toyota-ts030-hybrid-le-mans-effort

 

[TomT]

Actually, Le Mans racers don't do as much braking as you might think... Even with 100% efficient regeneration, you'd not be able to recapture more than about 30%...

I'll leave the math to those more qualified. What if they used something like 3X the modules, allowed a greater percentage of SOC utilization, and went mad with Cd and regen? Perhaps an ultracapacitor buffer for the regen, which must be intense at the deceleration these cars undergo.

 

[AP1]

With all your calculations, or not :?

Drivers switch cars during the race, returning to the original car once it has been recharged. A car battery contains three 200-cell units and, at top speed, a battery lasts up to 25 minutes, making for a race time of about one hour.

http://www.autoweek.com/article/20130227/motorsports/130229820#ixzz2M8dcPcgj

 

[Electric4Me]

I don't think I understand how it only takes twice the energy but three times the power. How exactly is that possible?

You're traveling faster so you're covering more ground thus using power for less time. Energy = power * time.

Since this is race that is timed, not a set distance, I don't think that will apply.

I definitely think that the electric race car will have to put a much higher priority on aero drag, and less on downforce, like the DeltaWing. It was competitive in spite of having much less power.

 

[Drivesolo]

With all your calculations, or not :?

Drivers switch cars during the race, returning to the original car once it has been recharged. A car battery contains three 200-cell units and, at top speed, a battery lasts up to 25 minutes, making for a race time of about one hour.

http://www.autoweek.com/article/20130227/motorsports/130229820#ixzz2M8dcPcgj

That's Formula E. There are other threads on this forum about that.

 

[AP1]

That's Formula E. There are other threads on this forum about that.

That maybe Formula E, but it tells you that they need a new battery every 25 minutes. If Nissan can stretch it to between 40-45 minutes (granted not easily done), that will be 33 pit stops.

 

[Drivesolo]

I don't think I understand how it only takes twice the energy but three times the power. How exactly is that possible?

You're traveling faster so you're covering more ground thus using power for less time. Energy = power * time.

Since this is race that is timed, not a set distance, I don't think that will apply.

I definitely think that the electric race car will have to put a much higher priority on aero drag, and less on downforce, like the DeltaWing. It was competitive in spite of having much less power.

There will be some benefits from not requiring as much cooling but the essential shape of the car will not change significantly from what other teams running some form of ICE. Downforce vs drag is a fine balance. Less downforce means better efficiency but the car will not be able to maintain as high of speeds in the corners and in addtion loose out on exit speed coming out of the corners. When dealing w/ speeds like Le Mans and the high-speed F1 circuits, aero is usually the bigger consideration than engine performance for ICEs.

There are a lot of disadvantages being mentioned so it might be worth mentioning some of the advantages. I would think that an EV Le Mans car would have the following advantages to it:
- Better aero due to lesser need for engine (motor & batt) cooling
- Regenerative braking: recoups some power, less wear on brakes, less drag from smaller brake ducts
- Better weight distribution: lower and/or more centralized
- Dual motors or even quad motors would allow better power delivery
- Simplified or single gear transmission

What other advantages would an EV have?

 

[Drivesolo]

That's Formula E. There are other threads on this forum about that.

That maybe Formula E, but it tells you that they need a new battery every 25 minutes. If Nissan can stretch it to between 40-45 minutes (granted not easily done), that will be 33 pit stops.

Ehhh..... yeah, but it says that they're topping out at 135mph. If a Le Mans car did that it would be at a serious disadvantage, it wouldn't be competitive in any class. It's not likely that it would be any faster in the corners to make up for that top speed deficit. A Le Mans car should be capable of nearly 200mph.

 

[ERG4ALL]

I hope someone has pointed out that it appears that they will be using hydrogen fuel cell technology, so there may not even be a propulsion battery in the car. Their biggest worry will be the storing of sufficient hydrogen. This makes for an interesting experiment, but if Mr. Ghosn was worried about the electric charging infrastructure, he'll have a greater worry about a hydrogen infrastructure.

will be filled by the GreenGT hydrogen fuel cell prototype this year.

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[Sublime]

The fact that these cells would need to be charged anywhere from 0 to 18 times during the race means they could use lots of different chemistries that are currently off limits to production cars because of cycle life.

That said I think the most likely form of "battery" for a competitive electric LeMans car will be a hydrogen fuel cell.

 

[DaveEV]

I hope someone has pointed out that it appears that they will be using hydrogen fuel cell technology, so there may not even be a propulsion battery in the car. Their biggest worry will be the storing of sufficient hydrogen. This makes for an interesting experiment, but if Mr. Ghosn was worried about the electric charging infrastructure, he'll have a greater worry about a hydrogen infrastructure.

All fuel cell vehicles have an electric battery on-board to act as a buffer between the fuel cell and motor. Fuel cells are not able to quickly vary their power output, and without a battery you'd need to electrolyse water into hydrogen if you wanted to do any regenerative braking.