Nissan Leaf

[thelastdeadmouse]

Even with air-cooling?

It seems that anywhere that doesn't have very, very hot sustained temperatures like parts Arizona and Texas haven't had any issues with the air cooling and battery life. Seattle would be fine. I agree with Duncan, I'd much prefer a Gen 3 for supercharging, as well as the added benefits of what's sure to be better performance and styling, but if a 150 -180 highway mile ranged Leaf came out significantly earlier and cheaper than a Gen 3 Tesla, it'd be hard to turn down.

 

[DuncanWatson]

Even with air-cooling?

I live in the Pac NW the place best suited to the current generation of Leafs. I wouldn't love air-cooling and hopefully the changes that Nissan have made live up to their claims but it wouldn't be a showstopper for me in the NW

 

[acentre]

My brother has a 2012 Leaf in Sarasota, Fl, leased December 2012 and has 6500 miles. He has lost the first battery bar already. I have 2013 and live in Rhinebeck NY, I have 8500 miles with no battery bar loss.

 

[jrreno]

Another data point, I have a 2012 Leaf leased in July 2012 and live in Sarasota. No bars lost yet , 6300 miles on the odometer.

 

[gasmiser1]

2011 Leaf, @ 37,500 miles we lost our 1st capacity bar. (Never QC'd), charged to 100%, 5 days a week, 80% on weekends. While we still love the LEAF, we look forward to 17 months from now when our lease ends and we get a P85 model S. More range = getting rid of another gas powered car we own for long trips. Model S is revolutionary and is a game changer for the EV enthusiast.

 

[TonyWilliams]

The LEAF battery is not "air cooled". The battery is a sealed unit. There is no fan, cooling fins, etc. The only contact it has to the LEAF car body are the half dozen or so mounting bolts (hence, no "heat sink" from the car).

The thermal protection that the battery has (except early 2011 models) is six 50 watt heaters that come on at -20C (-4F) to protect the battery from freezing (it only heats to -10C / 14F). For overheating, the Battery Management System (BMS) will begin limiting the battery functions at 50C / 122F.

Heat is the number one killer of the LEAF battery. It exceeds every other parameter by a LARGE margin. If your car is in a place that gets warm (above 80F), your LEAF battery will suffer. Above 100F, it may not survive a 36 month lease.

 

[Lloyd]

MIT and Nissan refers to them as Air Cooled...

http://www.technologyreview.com/view/429282/are-air-cooled-batteries-hurting-nissan-leaf-range/

 

[stopcrazypp]

The LEAF battery is not "air cooled". The battery is a sealed unit. There is no fan, cooling fins, etc. The only contact it has to the LEAF car body are the half dozen or so mounting bolts (hence, no "heat sink" from the car).

According to early Nissan PR, the Leaf battery has a fan inside the sealed pack to circulate air:
http://green.autoblog.com/2010/01/25/is-the-nissan-leaf-battery-pack-under-engineered/

Even though there are no cooling fins, the module plating and the pack plating already serves as a type of heat sink. The large surface area is enough to cause a rather large exchange of heat with the outside (I remember Leaf owners saying the battery temp can rise quite quickly when parked on top of hot asphalt).

 

[TonyWilliams]

According to early Nissan PR, the Leaf battery has a fan inside the sealed pack to circulate air:
http://green.autoblog.com/2010/01/25/is-the-nissan-leaf-battery-pack-under-engineered/

Yes, the prototypes had fans. No production LEAF battery does.

- - - Updated - - -

MIT and Nissan refers to them as Air Cooled...

http://www.technologyreview.com/view/429282/are-air-cooled-batteries-hurting-nissan-leaf-range/

I've read of lots of folks calling it "air cooled". How does air get in there to transfer heat? It doesn't.

The pack is not only sealed, it is slightly pressurized to keep out moisture. This is all straight out of the Nissan LEAF Service Manual.

Please read through this post that I compiled for "other" Nissan statements about the Nissan LEAF battery:

Battery Degradation Summary

 

[Doug_G]

I've read of lots of folks calling it "air cooled". How does air get in there to transfer heat? It doesn't.

Yes of course it is air cooled. If it weren't the temperature in the pack would go to infinity. It is passively cooled by convection of air against its outer skin. Internally heat is transferred through structure and perhaps through convection within the battery itself.

I'm not saying the cooling is terribly effective. I'm just saying it absolutely is air cooled. Just like your smartphone. No air goes in or out, but it is cooled through its outside surfaces.

 

[ItsNotAboutTheMoney]

Yes of course it is air cooled. If it weren't the temperature in the pack would go to infinity. It is passively cooled by convection of air against its outer skin. Internally heat is transferred through structure and perhaps through convection within the battery itself.

I'm not saying the cooling is terribly effective. I'm just saying it absolutely is air cooled. Just like your smartphone. No air goes in or out, but it is cooled through its outside surfaces.

And they will have designed in air flow. At least I'd expect so. Like the Prius uses a vent into the cabin, since people generally like to be close to the ideal battery temperature and that enlarges the air space without adding drag.

 

[TonyWilliams]

And they will have designed in air flow.

So, if we're going to be loosey goosey with air cooled, I guess everything then is air cooled. Well, maybe not so much in space.

There is no significant air flow around the sealed battery pack. The bottom of the car has an aerodynamic cover.

My Nissan Leaf Forum a Tour of the Dark Side

- - - Updated - - -

Yes of course it is air cooled. If it weren't the temperature in the pack would go to infinity. It is passively cooled by convection of air against its outer skin. Internally heat is transferred through structure and perhaps through convection within the battery itself.

I'm not saying the cooling is terribly effective. I'm just saying it absolutely is air cooled. Just like your smartphone. No air goes in or out, but it is cooled through its outside surfaces.

I'm using my air cooled brain to come up with an answer on my air cooled keypad. I'm just coming up with air. :tongue:

 

[stopcrazypp]

Technically, the general definition of "air cooled" only requires air flowing across a heat exchange surface. The bottom of the pack might qualify for this since there's plenty of air flow through there when the car is moving (the thread Tony posted shows some thin sound deadening in the front panel, but not sure how the rear is designed). If there's significant heat exchange to and from the pack via the bottom surface of the car, then I believe that still qualifies as air cooling (even though it's passive, not "active").

If the pack is well insulated from the outside (air flow on bottom of car does not significantly affect temperatures of the pack) then it's not air cooled.

This thread shows parking on top of hot asphalt does raise battery temps, but not sure of other way around (does air flow from driving lower/reduce battery temps). And that may be from the result of radiant heat rather than heat exchange from air, but it does show there is heat exchange from the shield on the bottom of the car to the pack.
http://www.mynissanleaf.com/viewtopic.php?f=30&t=9314

 

[Doug_G]

I'm using my air cooled brain to come up with an answer on my air cooled keypad. I'm just coming up with air. :tongue:

Your brain is liquid cooled internal to the body, but the body doesn't have any heat exchanger except through your skin (well maybe some through your lungs, but last I checked humans didn't pant like dogs). When ambient temperatures are high it uses evaporative cooling to boost natural convective cooling.

 

[TonyWilliams]

Your brain is liquid cooled internal to the body, but the body doesn't have any heat exchanger except through your skin (well maybe some through your lungs, but last I checked humans didn't pant like dogs). When ambient temperatures are high it uses evaporative cooling to boost natural convective cooling.

Anyhoo, like I said, the LEAF battery is about a "air cooled" as my brain, since both rely passively on ambient air to exchange any heat (my brain through the skull, skin and hair to air, and also through blood to capillaries to skin to air, potentially aided by sweat when certain programed parameters are met).

Dogs use their wet tongues as heat exchangers. Some humans, like those in sub-Sahara Africa, have well designed hair to reject UV heating, however that hair is also great at radiating heat to cool the top of the head.

The LEAF battery has no hair, wet tongues, sweat or blood. Not even a heat sink to the car's body. No radiating fins. No circulating fans.

And finally, Nissan had no real concept of how bad heat would affect these cells. They're changing several things now, post class action law suit, et al.

 

[acentre]

Good thing I leased my Leaf, poor battery life, no Chademo in my area . When I am ready to purchase it will be a 3 gen Tesla.

 

[ggies07]

I don't get it, why are they being so stubborn on battery thermal management?

 

[Doug_G]

Anyhoo, like I said, the LEAF battery is about a "air cooled" as my brain, since both rely passively on ambient air to exchange any heat (my brain through the skull, skin and hair to air, and also through blood to capillaries to skin to air, potentially aided by sweat when certain programed parameters are met).

Dogs use their wet tongues as heat exchangers. Some humans, like those in sub-Sahara Africa, have well designed hair to reject UV heating, however that hair is also great at radiating heat to cool the top of the head.

The LEAF battery has no hair, wet tongues, sweat or blood. Not even a heat sink to the car's body. No radiating fins. No circulating fans.

And finally, Nissan had no real concept of how bad heat would affect these cells. They're changing several things now, post class action law suit, et al.

I don't think we're really disagreeing here. The only point I'm making is that the Leaf is indeed "air cooled". It may not be a very effective system, but it works. Ish.

 

[TonyWilliams]

I don't get it, why are they being so stubborn on battery thermal management?

In a nutshell, they've painted themselves in a corner. To add a significant TMS would cost real money. They could do something cheap like pumping in air conditioned air into the battery, particularly when it's being quick charged.

Their goal is to make a heat resistant battery that doesn't require TMS.

 

[brianman]

Your brain is liquid cooled internal to the body, but the body doesn't have any heat exchanger except through your skin (well maybe some through your lungs, but last I checked humans didn't pant like dogs). When ambient temperatures are high it uses evaporative cooling to boost natural convective cooling.

Note to self: Don't play poker with Doug_G. I can tell from his post that this poker face is probably formidable.