Everything you might want to know about the '18 LEAF engineering

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OrientExpress

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For all you LEAF enthusiasts out there, here is an article from SAE International that deep dives into the '18 LEAF and all of the engineering that makes it what it is today. Enjoy, as I think you will be surprised at how much improvement there is over the 1st generation LEAF. BTW, SAE Automotive Engineering is a great resource for the professional automotive engineer and armchair automotive experts too!

LEAF Turns to the 2020s
 
10% degradation per 500 cycles. Environmental details were not mentioned

Ouch

Silver lining: at least this time around Nissan is being honest that the battery willl have poor longevity.
 
SageBrush said:
10% degradation per 500 cycles. Environmental details were not mentioned

Ouch

Silver lining: at least this time around Nissan is being honest that the battery willl have poor longevity.

Not so "ouch" if cycle life refers to full cycles, as the 60,000 mile claim suggests. The common use-case would be consuming only a partial cycle per drive. 15 percent degradation would extrapolate to 90,000 miles, which is far better than LEAF has performed previously.

If true, of course. ;)
 
Nubo said:
SageBrush said:
10% degradation per 500 cycles. Environmental details were not mentioned

Ouch

Silver lining: at least this time around Nissan is being honest that the battery willl have poor longevity.

Not so "ouch" if cycle life refers to full cycles, as the 60,000 mile claim suggests. The common use-case would be consuming only a partial cycle per drive. 15 percent degradation would extrapolate to 90,000 miles, which is far better than LEAF has performed previously.

If true, of course. ;)
I was guessing at average use of 50% SoC usage a day, so perhaps 2000 cycles till 80% capacity. That is about 6 years
Or 3000 cycles until 70% SoC

Right about where you would expect Nissan to be if they chose a warranty period to about match battery longevity, and pretty much in line with past Nissan behavior. The missing information has to do with climate but I don't expect Nissan to turn a new page here.
 
SageBrush said:
10% degradation per 500 cycles. Environmental details were not mentioned

Ouch

Silver lining: at least this time around Nissan is being honest that the battery willl have poor longevity.

that is 75,500 miles per the EPA so you will have 11½ bars after that. Alter your charging habits to DoD of 70% or 115 miles and push that to 11½ bars @ 100,000 miles.

But then again, I am guessing unless its 1% over half a million, it won't be good enough for you because it has a Nissan nameplate.
 
500 cycles over 60000 miles equates to 120 mi per cycle. That's about 80% percent discharge per cycle most likely 90% to 10%. That would give you 200K mi for a 33.3% loss in capacity which is most likely what Nissan was aiming for. That would give you a "Lifetime" battery in that it would exceed the expected life cycle of the car itself. 1600-1700 charge and discharge cycles doesn't seem unreasonable in a moderate climate but I suspect that since the underlying chemistry hasn't changed we're going to see early failures in hot climates just like the 30 KWH battery. The larger battery will delay failures a bit but I would expect that we'll still start to see failures after the 3 year mark.
 
DaveinOlyWA said:
SageBrush said:
10% degradation per 500 cycles. Environmental details were not mentioned

Ouch

Silver lining: at least this time around Nissan is being honest that the battery willl have poor longevity.

that is 75,500 miles per the EPA so you will have 11½ bars after that. Alter your charging habits to DoD of 70% or 115 miles and push that to 11½ bars @ 100,000 miles.
I'll quote you for posterity and giggles.

As for Nissan's god awful customer support, no reason to drag that filthy laundry into a technical discussion about battery longevity.
 
Using the latest battery chemistry (NMC 811) you can get 1250 charge/discharge cycles (2.8 vdc to 4.2 vdc I.E. 100% discharge) at 45 degrees C. before you lose 20% capacity. And that's at 1C charge and discharge rates. Goes up to 1500 cycles for 20 degrees C. For a 60 KWH battery, that works out to 250K miles. What's not mentioned is long term deterioration as these kind of tests are run end to end over a period of months. If long term storage is not a problem this could be a "lifetime" battery. With 200 amp charging available, TMS will still be necessary while charging to prevent overheating the battery during DC Fast Charging during road trips. You might get away without a TMS while home charging overnight or even during normal driving but DCFC is going to require it anyway so you might as well make use of it.

If you expect to get the DCFC time down to 15 to 30 minutes, you have to use a 2-4 C charge rate which is not a problem for the battery to accept but will definitely heat up the battery. That's why you need the TMS.
 
johnlocke said:
Using the latest battery chemistry (NMC 811) you can get 1250 charge/discharge cycles (2.8 vdc to 4.2 vdc I.E. 100% discharge) at 45 degrees C. before you lose 20% capacity. And that's at 1C charge and discharge rates. Goes up to 1500 cycles for 20 degrees C. For a 60 KWH battery, that works out to 250K miles. What's not mentioned is long term deterioration as these kind of tests are run end to end over a period of months. If long term storage is not a problem this could be a "lifetime" battery. With 200 amp charging available, TMS will still be necessary while charging to prevent overheating the battery during DC Fast Charging during road trips. You might get away without a TMS while home charging overnight or even during normal driving but DCFC is going to require it anyway so you might as well make use of it.

If you expect to get the DCFC time down to 15 to 30 minutes, you have to use a 2-4 C charge rate which is not a problem for the battery to accept but will definitely heat up the battery. That's why you need the TMS.

This is the same mistake Nissan made when testing the original pack. Pack cycles fine in a bonfire but when faced with the realities of life, it flopped. Why? because we don't charge and then drive. We charge.............................. and then drive a teeny bit. park, sit sit sit, then drive a teeny bit more.

I know a Bolter who plans to charge one day a week because of how much range he has. I told him, he would be better off to charge a few hours a day or every other day. Why charge to full if you don't have to? but he doesn't care. He has 150 more miles of range than he needs.

But then again, you look at random Teslas at 300,000 miles and everyone is shocked but why is it a surprise? Unlike us, their driving habits DO resemble a cycle test!

I know a Uberite who did 100,000 miles on his LEAF with 12 bars... again cause his driving patterns resemble a cycle test; fast charge, drive, fast charge, drive... sleep every other day.
 
Cycling losses mentioned, but what about calendar losses especially in a warm climate? Been there, done that. Enjoying my 2013 model S85, which lost about 5% of battery capacity over 4 years and 64,000 miles prior to me purchasing it.
 
Most Teslas get driven much like Leafs, mostly in town and short trips. There are lots of low mileage Teslas around and they don't show any real battery degradation even after 4-6 years. It's a different chemistry and the battery is charged much less often, once or twice a week is the norm and they only charge to 80% by default. The chemistry is the driving factor but fewer charges does help. The simple truth of the matter is Tesla guessed right and Nissan guessed wrong.
 
johnlocke said:
Most Teslas get driven much like Leafs, mostly in town and short trips. There are lots of low mileage Teslas around and they don't show any real battery degradation even after 4-6 years. It's a different chemistry and the battery is charged much less often, once or twice a week is the norm and they only charge to 80% by default. The chemistry is the driving factor but fewer charges does help. The simple truth of the matter is Tesla guessed right and Nissan guessed wrong.
And continues to guess wrong ... well, except for the thousand or so customers a month they snare.
 
SageBrush said:
johnlocke said:
Most Teslas get driven much like Leafs, mostly in town and short trips. There are lots of low mileage Teslas around and they don't show any real battery degradation even after 4-6 years. It's a different chemistry and the battery is charged much less often, once or twice a week is the norm and they only charge to 80% by default. The chemistry is the driving factor but fewer charges does help. The simple truth of the matter is Tesla guessed right and Nissan guessed wrong.
And continues to guess wrong ... well, except for the thousand or so customers a month they snare.

The new Leaf has an entirely new battery chemistry. It’s the same or very similar to that in the Power Wall. We don’t know if it will be as good as the batteries in Tesla vehicles, but I have high hopes.

Why do you hang out on a Leaf forum if you do nothing but spew negativity?
 
The new Leaf has an entirely new battery chemistry. It’s the same or very similar to that in the Power Wall. We don’t know if it will be as good as the batteries in Tesla vehicles, but I have high hopes.

We've been told it has a new chemistry, but after seeing the 30kwh pack replace the "Lizard" 24kwh pack with much worse chemistry, we are worried when we see that the 40kwh pack is also the same size and shape as the 30kwh pack. We are concerned that Nissan is chasing energy density at the expense of longevity.
 
jonathanfields4ever said:
The new Leaf has an entirely new battery chemistry. It’s the same or very similar to that in the Power Wall. We don’t know if it will be as good as the batteries in Tesla vehicles, but I have high hopes.
Without thermal control. THAT is the source of my negativity ... along of course with Nissan's track record of lying to and shafting EV owners for 15 years.

You bought the car and so somewhat naturally want to hear positive reinforcements about your choice.
I'm more interested in telling prospective buyers that a Nissan EV is ONE HUGE caveat emptor.
 
SageBrush said:
Without thermal control. THAT is the source of my negativity

Ford Focus Electric has "thermal control". Also has a similar record of capacity loss in hot places as the Leaf, and worse capacity loss in cool places.
 
WetEV said:
SageBrush said:
Without thermal control. THAT is the source of my negativity

Ford Focus Electric has "thermal control". Also has a similar record of capacity loss in hot places as the Leaf, and worse capacity loss in cool places.
So Ford has succeeded in making a battery crappy despite having a TMS. Nice

You do realize that does not diminish the utility of a TMS, right ?
For your argument to have merit, you would have to find a manufacturer without a TMS who succeeds in making a battery that is long-lived in a warm climate. Thus far that number sits at zero. You do have Nissan for a couple data points, but they are all failures.

But no doubt this time is *different* :lol:
 
SageBrush said:
WetEV said:
SageBrush said:
Without thermal control. THAT is the source of my negativity

Ford Focus Electric has "thermal control". Also has a similar record of capacity loss in hot places as the Leaf, and worse capacity loss in cool places.
So Ford has succeeded in making a battery crappy despite having a TMS. Nice

You do realize that does not diminish the utility of a TMS, right ?
For your argument to have merit, you would have to find a manufacturer without a TMS who succeeds in making a battery that is long-lived in a warm climate. Thus far that number sits at zero. You do have Nissan for a couple data points, but they are all failures.

But no doubt this time is *different* :lol:

And you have only one example of a manufacturer with long-lived battery packs, and it just happens to have thermal management. That doesn't really prove anything about the TMS since so many other things are dramatically, dramatically different. First is the chemistry, which from what I understand is a huge factor (NCA in the Tesla vs. LMO in the Leaf Gen1 vs. NMC in the Leaf Gen2 vs. maybe LCO??? in the pre-2017 Ford Focus). Teslas also charge at much higher wattages and have much higher output motors, which would seem to be the biggest reason for the inclusion of thermal management. The size of the battery is also important as a bigger battery will be cycled fewer times over its life.

I don't know if this is true, but a Nissan rep also told me that a large number of smaller cells help improve life because small defects can lead to deformation in the structure of an entire cell. So as many as 50 defects would be tolerable in a Tesla pack but would absolutely cripple a Leaf. There are just too many variables that better explain Tesla's great battery packs for us to say TMS is a real deciding factor.

As for Nissan's shafting of customers, that's definitely something I'm worried about with my new Leaf.
 
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