2016-2017 model year 30 kWh bar losers and capacity losses

SageBrush said:

We [Edit: I] know a change of chemical composition (maybe silicon was added?) is responsible for the increased capacity

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Evidence ?
Is Nissan overcharging the battery ?!

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Well, in the vaguest sense, you could say yes. overcharging for the chemistry and conditions? yes. By not allowing a 90% option, Nissan is pushing the envelop in order to gain a few extra miles.

In reality, its not possible to overcharge which is why you get no more than 97.7% but the closer to 100% you get, the less leeway you have when its 90º out. Didn't previous packs only charge to 97.3%?

DaveinOlyWA said:

Well, in the vaguest sense, you could say yes. overcharging for the chemistry and conditions? yes. By not allowing a 90% option, Nissan is pushing the envelop in order to gain a few extra miles.

In reality, its not possible to overcharge which is why you get no more than 97.7% but the closer to 100% you get, the less leeway you have when its 90º out. Didn't previous packs only charge to 97.3%?

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????

Nissan intentionally limits the max cell voltage to 4.11 VDC. A fully charged Li-ion cell max's out at 4.17-4.20 depending on the exact chemistry used. Because the voltage increase due to charging is non-linear near the top end of the range (I.E. it rises sharply at near full charge), charging by Nissan's BMS stops the charging process early. The battery is never charged to it's full capacity. Best guess is around 95% of full capacity but it might be as high as the 97% value reported by Leaf Spy. The same is true at the bottom end. Nissan limits the minimum voltage to 3.2 VDC. The cell can be discharged as low 2.8 VDC but there is very little energy left in the cells below 3.2 volts So Nissan limits the discharge. Best guess is around 4-5% capacity left at turtle. By limiting the charge and discharge, Nissan protects the battery somewhat. This also prevents "bricking" the battery through over-discharging it. At the top end It minimises the swelling of the cells and thereby limits mechanical damage.

I suspect that the values chosen represent a compromise between fully protecting the battery and extracting the maximum range from it. I also suspect that Nissan chose a very moderate use pattern in designing the battery. This would work well in Japan and Europe where cities are more compact and most driving is very short range.

Nissan limits the minimum voltage to 3.2 V

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Max voltage is 4.14V and minimum voltage is 2.5V. After contactor disengagement jump back to 2.6V is expected.

Keeping at 100% state of charge is not recommended whatever Nissan says. They say a lot of things and their batteries don't last.
Charging to 100% state and total discharge is totally fine. Just not fine to keep that for hours and hours at 6 or more temp bars.

arnis said:

They say a lot of things and their batteries don't last.
Charging to 100% state and total discharge is totally fine. Just not fine to keep that for hours and hours at 6 or more temp bars.

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I'd avoid the deep discharges if possible, but I agree with the charge up and use shortly thereafter advice.

I cannot remember ever seeing a battery at 98 SOH at 70k+ km. NIIIIICE

arnis said:

Nissan limits the minimum voltage to 3.2 V

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Max voltage is 4.14V and minimum voltage is 2.5V. After contactor disengagement jump back to 2.6V is expected.

Keeping at 100% state of charge is not recommended whatever Nissan says. They say a lot of things and their batteries don't last.
Charging to 100% state and total discharge is totally fine. Just not fine to keep that for hours and hours at 6 or more temp bars.

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Your VIN is for a 2014 leaf, so not sure if this info applies in your case?

SageBrush said:

I cannot remember ever seeing a battery at 98 SOH at 70k+ km. NIIIIICE

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Consider where he is located: https://en.wikipedia.org/wiki/Climate_of_Estonia

GRA said:

Consider where he is located: https://en.wikipedia.org/wiki/Climate_of_Estonia

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Climate is only one part of it. I would say that the fact it's not a 30 kWh battery that was mfg in the suspect date range has a LOT more to do with it. My climate https://en.wikipedia.org/wiki/Boulder,_Colorado#Climate is not that different and I've got nothing close to that.

ironmanco said:

GRA said:

Consider where he is located: https://en.wikipedia.org/wiki/Climate_of_Estonia

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Climate is only one part of it. I would say that the fact it's not a 30 kWh battery that was mfg in the suspect date range has a LOT more to do with it. My climate https://en.wikipedia.org/wiki/Boulder,_Colorado#Climate is not that different and I've got nothing close to that.

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I don’t recall any 30 kWh EU cars with excessive degradation so far.

jbuntz said:

I don’t recall any 30 kWh EU cars with excessive degradation so far.

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So - this statement seems to lean towards a bad batch of batteries for the US market?

ironmanco said:

jbuntz said:

I don’t recall any 30 kWh EU cars with excessive degradation so far.

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So - this statement seems to lean towards a bad batch of batteries for the US market?

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It also supports the idea that, like the Canary packs, they do OK in cool climates. We'd need info from Spain, because most of Europe is relatively cool.

LeftieBiker said:

It also supports the idea that, like the Canary packs, they do OK in cool climates. We'd need info from Spain, because most of Europe is relatively cool.

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But my point was that I'm a cooler climate - most of my charging happens when it's much cooler (<60F) and in some cases very cool. We may just not have enough data from the US 30 kWh batteries which reside in cooler areas of the US to determine if it's solely based on temp or bad production. Anyone care to provide some perspective on this?

ironmanco said:

LeftieBiker said:

It also supports the idea that, like the Canary packs, they do OK in cool climates. We'd need info from Spain, because most of Europe is relatively cool.

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But my point was that I'm a cooler climate - most of my charging happens when it's much cooler (<60F) and in some cases very cool. We may just not have enough data from the US 30 kWh batteries which reside in cooler areas of the US to determine if it's solely based on temp or bad production. Anyone care to provide some perspective on this?

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Some of the 2011-2012 packs degraded even in what we consider to be cool climates. Temps like your may be a prerequisite for longer life for packs with poor chemistry, but they don't guarantee it. It would help a lot to know hot warm your pack gets, as opposed to the outside temps.

2011-2012 Leaf packs degrade even here, in cold climates. Though for now usually 1-2 bar loss expected.

Another thing to keep in mind is that in EU, majority of Leafs are charged to 80% as default.
Though, AFAIK, charging to 100% has limited effect (somewhat like +10...+20% faster degradation) here. More if hot.
Leaf's that only QC (taxi) degrade like a third faster (per distance) - (QC does not degrade, temperature rise does).


6th temperature bar is the first bar to avoid in long term.
30kWh packs have slightly worse pack thermal design (cell pouches more crammed). And they can also be heated up
more easily as they QC way way faster.
Some Ukrainian Leaf importers (cars from US) have commented, that rear stack middle third modules are the likeliest to
lose capacity too fast. And reason is that those cool down the slowest, after high speed drive or QC session.


My car proves, that deep discharges matter little (hundred+ cycles below 3V per cell).
Though I can confirm, that discharging below VLBW will heat up battery CONSIDERABLY.

How to prolong pack life? Keep the average SOC low. This applies to almost all li ion chemistries. Jeff Dahn's words.
Accelerated Leaf's battery degradation does NOT happen due to cycling nor charging speed (me+taxies here prove).
It happens due to reactions in the battery happening at elevated (50+%) states of charge when pack is warm (6+bars).
This means in hot climates + 24/30kWh Leaf - do not charge above 50% if you don't need the range. Low limit is VLBW.
There is no data that shows accelerated degradation due to short-lasting low states of charge (I'm example that it is not true).
Keep in mind ideal storage SOC is 30%-50%. And that low limit is just to be sure it never drops dead. Which will NEVER
happen on a car, that is used daily/weekly.
Forget adjusting charging timing to sit in a "cold" soaked pack. Keep SOC below 50% for as long as possible. 6 bar's is not cold.
If you can't get it down to 5 bars, do not charge above 50%. Except if you discharge it within hours.

arnis said:

Forget adjusting charging timing to sit in a "cold" soaked pack.

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I'm not sure I understand this comment, but I agree with the rest of your post.

We let the car battery drop to 30-40% SOC from use before we charge it back up to 80%. Charging is set to start at 5am and performed outside in the summer. This is the coolest time of day and about an hour or two before use. I thought about asking my wife to recharge when the SoC hits the 20-30% level but that provokes range anxiety.

I think most of us can agree that heat is a first order cause of degradation for all electronics, batteries even more, and acutely so in the LEAF. It is almost painful to think of the LEAF owners in hot climates who thought they were taking care of their cars by parking in closed hot garages every day and charging the battery to 100% soon after parking.

As much as I am a harsh critic of Nissan, I do think that the 2013-2016 24 kwh packs can be reasonably expected to last 8-10 years if they are pampered and in mild climates. The jury is out on the 30 kWh packs, but it is not looking good.

ironmanco said:

LeftieBiker said:

It also supports the idea that, like the Canary packs, they do OK in cool climates. We'd need info from Spain, because most of Europe is relatively cool.

Click to expand...

But my point was that I'm a cooler climate - most of my charging happens when it's much cooler (<60F) and in some cases very cool. We may just not have enough data from the US 30 kWh batteries which reside in cooler areas of the US to determine if it's solely based on temp or bad production. Anyone care to provide some perspective on this?

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We have one in Northwest Oregon who lost over 10% in less than a year. He had 2015 build pack. His weather is not as marine controlled as mine but the differences aren't significant from mine... or are they? Do we really know what is significant?

DaveinOlyWA said:

ironmanco said:

LeftieBiker said:

It also supports the idea that, like the Canary packs, they do OK in cool climates. We'd need info from Spain, because most of Europe is relatively cool.

Click to expand...

But my point was that I'm a cooler climate - most of my charging happens when it's much cooler (<60F) and in some cases very cool. We may just not have enough data from the US 30 kWh batteries which reside in cooler areas of the US to determine if it's solely based on temp or bad production. Anyone care to provide some perspective on this?

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We have one in Northwest Oregon who lost over 10% in less than a year. He had 2015 build pack. His weather is not as marine controlled as mine but the differences aren't significant from mine... or are they? Do we really know what is significant?

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Ask Arrhenius

SageBrush said:

arnis said:

Forget adjusting charging timing to sit in a "cold" soaked pack.

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I'm not sure I understand this comment, but I agree with the rest of your post.

We let the car battery drop to 30-40% SOC from use before we charge it back up to 80%. Charging is set to start at 5am and performed outside in the summer. This is the coolest time of day and about an hour or two before use. I thought about asking my wife to recharge when the SoC hits the 20-30% level but that provokes range anxiety.

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I recommended not to think about how to keep battery as cold as possible before trip.
It's fine to drive a Leaf that was just charging and has battery temp above ambient.


You charge up to 80% but do you discharge it within few hours down to 50%? If not, consider not charging up to 80%.
Start charging at 7am so that SOC is below 80% when trip starts. So it is near 50% mark soon after.

It appears that heat degradation is many times slower at 30% SOC compared to 80%.
Though it is hard to keep a car so low. It's a vehicle that should be used daily. There is no range at 30% SOC :lol:

arnis said:

SageBrush said:

arnis said:

Forget adjusting charging timing to sit in a "cold" soaked pack.

Click to expand...

I'm not sure I understand this comment, but I agree with the rest of your post.

We let the car battery drop to 30-40% SOC from use before we charge it back up to 80%. Charging is set to start at 5am and performed outside in the summer. This is the coolest time of day and about an hour or two before use. I thought about asking my wife to recharge when the SoC hits the 20-30% level but that provokes range anxiety.

Click to expand...

I recommended not to think about how to keep battery as cold as possible before trip.
It's fine to drive a Leaf that was just charging and has battery temp above ambient.


You charge up to 80% but do you discharge it within few hours down to 50%? If not, consider not charging up to 80%.
Start charging at 7am so that SOC is below 80% when trip starts. So it is near 50% mark soon after.

It appears that heat degradation is many times slower at 30% SOC compared to 80%.
Though it is hard to keep a car so low. It's a vehicle that should be used daily. There is no range at 30% SOC :lol:

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the key takeaway here should be limiting the TIME at high SOC and heat. It is ok to heat up pack and its ok to charge to high SOC. Simply don't let it stew that way. These little tiny "I charged to full on level 2 in the middle of the day at work and left right away" might sound good to you but on level 2 that means as much as 2 hours at a high SOC. This is what is hurting us. Its a tiny thing for sure but 2, 3 hours every day becomes a big thing.

arnis said:

SageBrush said:

arnis said:

Forget adjusting charging timing to sit in a "cold" soaked pack.

Click to expand...

I'm not sure I understand this comment, but I agree with the rest of your post.

We let the car battery drop to 30-40% SOC from use before we charge it back up to 80%. Charging is set to start at 5am and performed outside in the summer. This is the coolest time of day and about an hour or two before use. I thought about asking my wife to recharge when the SoC hits the 20-30% level but that provokes range anxiety.

Click to expand...

You charge up to 80% but do you discharge it within few hours down to 50%? If not, consider not charging up to 80%.
Start charging at 7am so that SOC is below 80% when trip starts. So it is near 50% mark soon after.

Click to expand...

The charge is set to finish at 6am, and the car is used between 6am and 9am. The end of charging battery temperature is 6 bars in the summer and 3-4 bars in the winter. Each trip knocks about 10% off the SoC

I call that babying the battery, but it could always be a bit better.