Nissan buys back my Leaf

[TimLee]

... The LEAF does have passive cooling with some air flow into and out of the battery box while driving. Even with the "Hot" battery, Nissan maybe should consider a forced air flow system. ...:

Nope. The battery box is sealed. No air flow at all.

Thanks for catching the error. I corrected the original post.
While the vehicle is moving openings in the plastic cover panels catch air and direct it across the bottom of the steel battery box.
See references to the pictures at: http://www.mynissanleaf.com/viewtopic.p ... 10#p290708" onclick="window.open(this.href);return false;
The steel box is completely sealed, air and water tight. There is a battery air leak test that is done, apparently for the newer packs, where the two halves of the case are bonded together. See:
http://www.mynissanleaf.com/viewtopic.p ... 10#p313433" onclick="window.open(this.href);return false;

[Volusiano]

If the new heat-resistant battery lives up to Nissan's projections, and comes out only ~ one year from now, the proof of the superiority of Nissan's approach over that taken by virtually all other BEV manufactures will have come even earlier than I expected.

I disagree. Nissan's approach is not superior to other BEV manufacturers at all. It is inferior. Why? Because it didn't have TMS when it manufactured an BEV that doesn't have a heat-resistant battery.

The fact that Nissan's may have a heat-resistant battery a year from now doesn't mean that it's vindicated for making the wrong decision too prematurely. What Nissan should have done is to implement TMS to begin with, then drop TMS when it has a heat-resistant battery, but not until then.

That's what other BEV will do when they have a heat-resistant battery, drop TMS, but not until then. Other BEV mfgs did the right thing. Nissan did the wrong thing.

So Nissan's approach is inferior and is nothing to crow about.

[LeftieBiker]

You folks do realize that the Leaf - at least the 2013 version - will also 'lose charge just sitting around' in cold weather, right? The battery warmer will drain most of the pack - maybe even all of it, I'm not sure of the exact wording in the manual now. They could have put low-current fans in the blasted air passages, at least...

[Volusiano]

You also have to consider the high maintenance and repair costs battery cooling will require you to pay in the future.

The battery cooling uses the same AC system (compressor/condensor/freon loop) as the cabin cooling system. So it's misleading to claim that the battery cooling has its own separate AC system and therefore is higher maintenance and more repair cost. After all, the LEAF requires an AC system for cabin cooling, too, doesn't it? Same AC system is used for cooling the battery, so how can it be higher maintenance and higher repair cost?

If somebody argues that even though it shares the same AC system with the cabin cooling, the battery cooling requires its own liquid coolant loop because cabin cooling is through air exchange in the evaporator while battery cooling is through liquid coolant exchange in its own evaporator/chiller, then true. But consider the additional advantage of the battery coolant loop that a non-TMS system doesn't have and is not mentioned here: BATTERY HEATING. This is THE OTHER HALF of the operation that's not mentioned, and is a very important part of winter operation where the battery can ALSO be kept warm to be efficient and not lose significant range.

Another important aspect that's not mentioned about TMS here is that even when no cooling or heating is required, circulating the liquid coolant throughout the battery is also helpful to maintain battery cells' temperature stability, ensuring that there are no hot spots in certain cells in certain areas of the battery and not others.

So to summarize:

1. No extra high maintenance and high repair cost for battery cooling when it comes to the AC system because it uses the same AC system for cabin cooling.
2. The extra hardware for the battery liquid loop and pump is helpful not just for cooling only, but also helpful for heating and for maintaining battery cell temperature stability. So this extra hardware is justified to have.

[Berlino]

You folks do realize that the Leaf - at least the 2013 version - will also 'lose charge just sitting around' in cold weather, right? The battery warmer will drain most of the pack - maybe even all of it, I'm not sure of the exact wording in the manual now. They could have put low-current fans in the blasted air passages, at least...

It has to be very cold, 5F, for the battery warmer to kick in. Then, if the LEAF is plugged no charge will normally be lost, because whatever is consumed by the warmer will drawn from the external source. If the LEAF is unplugged, the warmer will run the battery down to 30% before shutting off. I believe the warmer is 300W, so if the battery is holding 16kWh, it will take about 40 hours to get down to 30%.

[Leaf1]

My understanding is that the cold weather package adds insulation to the battery pack. Is it conceivable that such insulation could further protect capacity by keeping overall temp fluctuations reduced? My Leaf never gets over 6 bars on the temp no matter how hot it gets - 90's is not uncommon in MD so not sure if this is a possible impact of the added insulation.
Has anyone studied the capacity loss differences in cars with and without the cold weather package?

[leafkabob]

I think it is interesting that Nissan did not mention to me, when it bought back my Leaf in January, that the testing of a hot weather battery was in the works. Perhaps they weren't sure that it would be a success. It seems hard to believe that in January the hot battery would not have been in some stage of development. I would have expected them to encourage us "buybacks" to hold off a bit longer and offer us a coupon for the new hot battery.

[Volusiano]

After all the recent fiasco of not just the battery heat issue but also the battery price issue (Andy Palmer vehemently promised a price then backed off and apologized), I don't believe in anything Nissan says anymore until I see it for myself. A 2014 release of a hot battery can easily slip into 2015 or 2016 due to some excuse. I wouldn't hold my breath waiting for the promise of one and plan to make purchasing/leasing decisions based on this promise.