Future LEAFs Needs Battery Thermal Mangement

I feel that Nissan needs to add an active Battery Thermal Management System to the LEAF

I love my 2011 LEAF and plan to keep it for 8+ years, but will most likely replace it with another BEV (not LEAF) if the LEAF does not have an active battery thermal management system.

Based on personal experience, my 2011 LEAF battery is not suitable for my climate (AZ). Early on, Musk (Tesla) questioned Nissan's decision not to add a thermal management system and predicted rapid battery capacity loss. Unfortunately, the LEAF now is associated with concerns of significant battery capacity degradation. Today, many cautious LEAF owners prefer to lease. I do not know if a leasing approach will sustain a high volume production business model. Especially with a limited market for used LEAFs due to battery capacity concerns.

If Tesla does release the Model E, I can envision Tesla again highlighting the Nissan LEAF's lack of a battery management system compared with Tesla's data showing excellent battery capacity aging of the Roadster and possible future data for the Model S and Model X.

I feel it would be better for Nissan to release a battery thermal management system using proven available LiB technology, than release a "jaw breaking", unproven, probably more expensive new LIB technology in 2017 to compete with future BEVs (many of which will probably have an active battery thermal management system). Nissan can elect to remove the battery thermal management system in future models if the new technology meets the performance targets.

Somewhere along the line, Nissan's battery testing failed. Whether that was due to flawed asumptions, inadequate methods, or "selective reporting" by engineers afflicted with "Go Fever", we'll probably never know. It's certainly resulted in disappointed drivers.

That being said, I hope they can find a way to produce a durable battery that is still TMS-free. Thermal management is an energy sink and presents challenges and owner disadvantages of its own. I like knowing that when I turn my LEAF off, it's off and if I park it with 5 bars I can come back a month later to 5 bars. Try that with a Tesla. Thermal management is a kludge to make up for flawed batteries. I'd much rather see improved batteries.

Well I for one, hope they don't. Read the Volt thread where one talks about the loss of EV range during some particularly hot weather. 25%? that is a LOT especially when you have no gas to rely on.

That is the dilemma the LEAF faces. So we have to have a MUCH bigger battery pack and TMS which adds a lot to the cost or

A bigger battery pack along with a tweaked chemistry that adds a little to the cost and allows me to accept the degradation I see because it will be 10 years before I have to worry about it instead of 2½ years (I have a large driving need, closer to 4 years for "normal" people)

so you see, its a "chicken verses egg" situation with a twist. Why buy eggs when Chicken is the same price?

Nubo said:

I like knowing that when I turn my LEAF off, it's off and if I park it with 5 bars I can come back a month later to 5 bars. Try that with a Tesla.

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Most of the vampire losses in the Model S appear to be to other auxiliary computers running in the car to provide things like remote access, auto-presenting door handles, etc and not TMS. At least in most climates. AZ summer may be a different story.

Tesla doesn't seem to activate TMS until the pack gets pretty hot in the Model S, appears to have higher thermal limits than the Roadster, for example. TMS doesn't even appear to activate until the battery is well over 100F when parked. When charging on 120V, the car is much less reluctant to use TMS as well preferring to add charge vs conditioning the pack. When SuperCharging, on the other hand, it's not hard to get the car to put maximum effort into cooling the pack and you can hear the fans running at full bore in hot weather. Tesla is able to do this because their batteries are much more tolerant of heat than the LiMn Nissan/GM is using.

The video in this thread has some great detail in terms of how much better Tesla's base chemistry is:
Why do lithium batteries die and how to improve them?
Forward to 26:00 or so - the charts on that page suggest that Tesla-like chemistry is more durable at 30C than the LEAF/Volt-like chemistries at the same temperature.

Nubo said:

Thermal management is a kludge to make up for flawed batteries. I'd much rather see improved batteries.

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Definitely. Hard to see thermal management not being required if one wishes to perform multiple QCs combined with freeway speed driving, though, at least with today's batteries.

DaveinOlyWA said:

Well I for one, hope they don't. Read the Volt thread where one talks about the loss of EV range during some particularly hot weather. 25%? that is a LOT especially when you have no gas to rely on.

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That was me. On the plus side, now we're back to "normal" in this part of the world the Volt is performing as we've expected all along. I've also been reminded that you can leave the Volt plugged in on really hot days, even when not charging, and the car will decide when to run thermal management off-the-grid. That's what we're going to try moving forward - I'd rather start out with a cooled battery than have the car trying to cool down an already hot battery while it's in use.

That said, I think my ultimate preference is for a robust battery chemistry/architecture that holds up well without active thermal management (in hot climes). That's what I would hold out hope for in the LEAF going forward, and obviously we're not there yet (at least not without knowing more about the "Lizard" pack).

I guess my main need is whatever drives down the price of the car. TMS ain't gonna do that.

Now, would I pay $2,000-3,000, or $4,000 more for more range? oh ya, definitely if it gives me at least 75 to 100% more range. Ya see; I feel that my next LEAF should cost the same and give me 30% more range so to pay a higher price, it would have to give me a lot more range.

I simply do not see that happening with TMS added to the mix. What I do see as possible is a more robust chemistry that slows degradation in higher heat situations. So I categorize myself in the

"low hanging fruit EVer" crowd

drees said:

Nubo said:

Thermal management is a kludge to make up for flawed batteries. I'd much rather see improved batteries.

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Definitely. Hard to see thermal management not being required if one wishes to perform multiple QCs combined with freeway speed driving, though, at least with today's batteries.

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Maybe the QC station can be combined with a cooling station. So in addition to the power connector you have connect cooling liquid lines if you need to. Now there is going to be a problem with a cooling "water" connector standard.

Nubo said:

Thermal management is a kludge to make up for flawed batteries. I'd much rather see improved batteries.

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I originally had similar thoughts, but I am not sure if Nissan has a lot of time to develop / implement an substantially improved heat tolerant battery.

I am not sure if I would call the batteries flawed. They hold up well to frequent charging in Seattle.

I would like the option to at least cool the pack at night whenever I plug in to charge.

As many have observed the pack takes a long time to cool down. The battery pack does not cool to the evening temperatures in AZ. It maybe 100F during charging and 90F in the morning. Parking in the driveway does not make any difference. In the afternoons when driving home, the pack quickly heats up to a few degrees below ambient.

Capacity loss seems to be a very popular topic on this forum, I am not sure if capacity loss is widely discussed on the Tesla forum.

myleaf said:

I originally had similar thoughts, but I am not sure if Nissan has a lot of time to develop / implement an substantially improved heat tolerant battery.

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Not sure whether you are following the news - but Nissan says hot battery will be released this summer.

Considering how Japanese companies work - my guess is this hot battery will meet, if not exceed, expectations. Having had this big degradation issue, they would be more careful this time.

Nubo said:

Somewhere along the line, Nissan's battery testing failed. Whether that was due to flawed asumptions, inadequate methods, or "selective reporting" by engineers afflicted with "Go Fever", we'll probably never know. It's certainly resulted in disappointed drivers.

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We can probably read all about this in some article/book in a few years. My guess would be some kind of management decision to downplay degradation. It is possible the designers were not aware of how hot it could get in US southwest and thought 100+ F was extreme and "edge case".

Before the car was released, Nissan put out some news release which talked about how the cars should not be "stored" in 100+ F condition for long. Apparently they didn't realize that would be quite normal in AZ and even chose AZ as one of the 5 starting states.

evnow said:

We can probably read all about this in some article/book in a few years. My guess would be some kind of management decision to downplay degradation. It is possible the designers were not aware of how hot it could get in US southwest and thought 100+ F was extreme and "edge case".

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What was surprising, I recall it mentioned that Nissan has battery test/development(?) facility in AZ and have been testing the batteries before the LEAF launched. It could have been just a business decision to go ahead with the launch.


I also hope we do not see it some article/book: Who Killed the Nissan LEAF?

myleaf said:

What was surprising, I recall it mentioned that Nissan has battery test/development(?) facility in AZ and have been testing the batteries before the LEAF launched. It could have been just a business decision to go ahead with the launch.

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Likely we will never know for sure what happened.

My guess is that the figure of 70% at 10-years was projected for the next battery design. Ghosn didn't want to delay launching the car and challenging Toyota for the "eco" crown. Expectations for degradation of the initial battery design and schedule for the next battery design led them to conclude that well before a significant number of cars suffered serious degradation they would have the improved battery, and would cheaply replace batteries in the small number of cars affected without many people noticing they ever had a problem. Then reality bit them: the initial battery was much worse than they thought, and the next battery was much further from production than they thought. So here we are.

I wonder whether this summer's lizard battery is the "next" battery Nissan was counting on, or whether it is a short term stopgap design intended to buy them enough time to come up with the real solution.

Nissan could easily avoid range loss and vampire loads by just cooling the battery when plugged in.
As long as the battery was cooled to 65/72 zone once a day the longevity improvement would be huge IMO.

smkettner said:

Nissan could easily avoid range loss and vampire loads by just cooling the battery when plugged in.
As long as the battery was cooled to 65/72 zone once a day the longevity improvement would be huge IMO.

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I agree !

I was on a long trip recently with multiple quick charges, my battery temp was 9 bars, and it was only 65 degrees outside. Just for fun I felt under the car to see if any heat was radiating... and I found... plastic. You know it would be so simple just to thermally connect each battery module to a metal plate that is exposed to the air (or water that splashes) under the car. Just let the heat radiate off naturally. Nissan doesn't even do that.

johnrhansen said:

I was on a long trip recently with multiple quick charges, my battery temp was 9 bars, and it was only 65 degrees outside. Just for fun I felt under the car to see if any heat was radiating... and I found... plastic. You know it would be so simple just to thermally connect each battery module to a metal plate that is exposed to the air (or water that splashes) under the car. Just let the heat radiate off naturally. Nissan doesn't even do that.

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Yup. That would be fantastic in moderate climates and still at least a wash in AZ. Sure, the battery would get hotter in the middle of the day, but at least it would get to cool down at night.

walterbays said:

Then reality bit them: the initial battery was much worse than they thought...

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That is the question - how come Nissan not know this from their tests ?

johnrhansen said:

I was on a long trip recently with multiple quick charges, my battery temp was 9 bars, and it was only 65 degrees outside. Just for fun I felt under the car to see if any heat was radiating... and I found... plastic. You know it would be so simple just to thermally connect each battery module to a metal plate that is exposed to the air (or water that splashes) under the car. Just let the heat radiate off naturally. Nissan doesn't even do that.

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Plenty of air moves around the pack when the car is moving. When the car is standing still? Not so much... Probably wouldn't take more than a 10W fan to move enough air to significantly reduce the amount of time it takes to cool a pack to near ambient.

evnow said:

myleaf said:

I originally had similar thoughts, but I am not sure if Nissan has a lot of time to develop / implement an substantially improved heat tolerant battery.

Click to expand...

Not sure whether you are following the news - but Nissan says hot battery will be released this summer.

Considering how Japanese companies work - my guess is this hot battery will meet, if not exceed, expectations. Having had this big degradation issue, they would be more careful this time.

Click to expand...

I will go a step further and say that Nissan had already developed a type of heat resistant battery but declined to use it for one reason or another. So this might very well be going back to what they already knew combined with newer technology.

One thing I will say about Tesla is their reaction time is much faster than Nissan's. Seems like every change Nissan makes is at a snail's pace

Nubo said:

Somewhere along the line, Nissan's battery testing failed. Whether that was due to flawed asumptions, inadequate methods, or "selective reporting" by engineers afflicted with "Go Fever", we'll probably never know.

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I think its quite clear from that professor's video how Nissan's battery testing was flawed. Someone else just linked it, but I'll link it again for emphasis:
http://www.mynissanleaf.com/viewtopic.php?f=9&t=15796" onclick="window.open(this.href);return false;
Most manufacturer's battery testing does not accurately predict the capacity OVER TIME. By rapidly discharging and charging the battery, even at elevated temperatures, they are just trying to "beat the clock". That university's new testing procedures give me high hopes that the next generation of batteries will have both increased cycling ability and heat tolerance. Unfortunately, those testing methodologies weren't available when Nissan did their evaluation. I have no desire for the added complexity and energy consumption of a thermal management system, and after seeing that video I am convinced that it will not be necessary if they can get the right chemistry recipe.