The 40KWH Battery Topic

[DougWantsALeaf]

I agree in the earlier batteries that the warm environments lead to faster decay.

What is yet to be seen is how much the warmer environments hurt the new chemistry.

I find it interesting that Tesla will bring up the temp to close to 50C for charging, and leave it above 40 at other times. Those temps would have killed the old Leaf battery, but not sure about the new one.

 

[DaveinOlyWA]

The evidence is a bit dubious as to how much QC hurts the new batteries if at all.

Well, heat is a catalyst that makes an undesirable situation worse. I would be much more worried about time at high SOC. I know a lot of people say just don't let it sit or whatever but EVERY second is detrimental. But if you need the range then you need the range. But if you don't and you are randomly charging to 100% every 3 days, then you are not doing the best for your pack.

So avoid...what?

Nothing. Can't really avoid most of the bad stuff anyway. Remember degradation is death by a million tiny cuts. Your goal is keeping that cut count to a few hundred thousand.

 

[DaveinOlyWA]

I agree in the earlier batteries that the warm environments lead to faster decay.

What is yet to be seen is how much the warmer environments hurt the new chemistry.

I find it interesting that Tesla will bring up the temp to close to 50C for charging, and leave it above 40 at other times. Those temps would have killed the old Leaf battery, but not sure about the new one.

The newer packs have leveled the playing field. I used to have a HUGE advantage in the degradation race but not so much anymore. The gap between the top and bottom is much smaller now. Maybe its too early yet but we have 2018's nearing 50,000 miles and more and they have not dropped away from the pack.

 

[DougWantsALeaf]

I was looking around and it looks like the Early small Tesla packs also suffered from some significant degradation.

https://forums.tesla.com/forum/forums/40-kwh-owners-anyone-out-there-0

https://forums.tesla.com/no_NO/forum/forums/40kwh-battery-degradation?page=2

As there were only ~500 40kWh model S’ so sample size is small.

 

[danrjones]

I agree in the earlier batteries that the warm environments lead to faster decay.

What is yet to be seen is how much the warmer environments hurt the new chemistry.

I find it interesting that Tesla will bring up the temp to close to 50C for charging, and leave it above 40 at other times. Those temps would have killed the old Leaf battery, but not sure about the new one.

The newer packs have leveled the playing field. I used to have a HUGE advantage in the degradation race but not so much anymore. The gap between the top and bottom is much smaller now. Maybe its too early yet but we have 2018's nearing 50,000 miles and more and they have not dropped away from the pack.

To me this is confusing. I agree we have seen data on here that puts people with 20 or 30 thousand miles at basically the same degredation as my pack with 4700 miles.

But essentially lots more miles means more cycles than my pack. Cycles degrade packs. So how can a vehicle with 8 times as many cycles end up with the same degredation?

One answer I can think of is that something else is degrading my pack. Heat would be a plausible answer. So I would not dismiss heat so quickly.

I think we will know soon. If I am correct, this summer will show us in my data.

 

[LeftieBiker]

Nissan seems to have come up with a pack that resists heat and cycling degradation, but not calendar degradation. Remember that episode of Lost In Space where John Robinson is being hunted, and has to choose a weapon or defense from a selection of known defective devices? Nissan Leafs are a bit like that.

 

[danrjones]

Nissan seems to have come up with a pack that resists heat and cycling degradation, but not calendar degradation. Remember that episode of Lost In Space where John Robinson is being hunted, and has to choose a weapon or defense from a selection of known defective devices? Nissan Leafs are a bit like that.

So basically its chemically unstable? Or has a set half life. Lol

Well we will know this summer.

 

[DaveinOlyWA]

I agree in the earlier batteries that the warm environments lead to faster decay.

What is yet to be seen is how much the warmer environments hurt the new chemistry.

I find it interesting that Tesla will bring up the temp to close to 50C for charging, and leave it above 40 at other times. Those temps would have killed the old Leaf battery, but not sure about the new one.

The newer packs have leveled the playing field. I used to have a HUGE advantage in the degradation race but not so much anymore. The gap between the top and bottom is much smaller now. Maybe its too early yet but we have 2018's nearing 50,000 miles and more and they have not dropped away from the pack.

To me this is confusing. I agree we have seen data on here that puts people with 20 or 30 thousand miles at basically the same degredation as my pack with 4700 miles.

But essentially lots more miles means more cycles than my pack. Cycles degrade packs. So how can a vehicle with 8 times as many cycles end up with the same degradation?

One answer I can think of is that something else is degrading my pack. Heat would be a plausible answer. So I would not dismiss heat so quickly.

I think we will know soon. If I am correct, this summer will show us in my data.

The #1 Degradation factor is time. Its unavoidable BUT, its not linear.

You can slow down time by icing the pack at 45% SOC (or 40 or 50...depending on who you talk to) or speed it up by charging to 100% on a hot Summer day. But it is mostly time.

But we also see people both with 2013's one has 100,000 miles 12 bars and charges to full every day. The other person has 20,000 miles, 9 bars and only charges to full 2-3 times a week. Why the difference? The 12 bar car obviously had easier time. Miles, cycling, all that stuff is a tiny part of the equation which should be obvious to all of us by now.

No custom charge settings means a lot of work to manage charge levels or simply charging to too high a level when its not needed.

So why does the 12 bar LEAF who charges to 100% every night do so well? Because he drives a lot and by default, he spends less time at high SOC. Remember the ideal SOC is 45%. So every day he is going from 100% to 20% and back which means spending a few hours at 100%, 8 hours at 60%, a few hours at 20% then several hours progressing from 21% to 100% again. What was his average SOC during the day?

The 9 Bar LEAFer. Charges to 100% and drives thru out the day down to 75%. The next day, he drives it down to 50%. The next day to 25% then he charges it back to 100%. During that 3 day stretch, what was his average SOC? More importantly, how much time did he spend at high SOC? What is high SOC? Anything over 80%? 70%? What if it was anything over 65%?

What we are finding out is all those scenario's contribute different values to a cycle. The more extreme ends; higher SOC, warmer than 80º. etc. add more value to the cycle count.

I have a phone app that manages my battery. If charging from a set point; I can set my SOC to 75% (my default) and its a .10 cycle hit. Charge it to 90%, its a .39 cycle hit. Charge it to 100% and its a .91 cycle hit. Charging to 100% on my phone is supposedly 9 times more stressful on my battery than charging to 75%. Get the picture?

Now with the 24 kwh pack, it was hard... no, simply not feasible to cycle the middle of the pack. Just not enough range. But now, I have a 62 kwh pack. Its a completely different World. I "should" be able get much more from this pack than any other.

So I am not expecting 2½ times better; I am expecting 5X better because my pack is doing easy time nearly all the time.

 

[HerdingElectrons]

I could indeed adjust my charge time, which I have set to about ~2 hrs after I depart but also set to "full charge has priority", to maybe about 3 hrs after I really depart. Right now it seems to get me right around 80%. But the battery really should be fine charging to 80%. If Nissan didn't build it well enough to survive my (non harsh, only one QC) charging habits and low mileage, that will be on them to fix it.

I'll update my stats in about a day or two when it is done adjusting.

This isn't a Nissan thing, it's a lithium ion chemistry thing:

https://batteryuniversity.com/index.php/learn/article/how_to_prolong_lithium_based_batteries

The battery will be "fine" at 80% but it will be happier at 75% & even happier at 65%. My point is that if you don't NEED the extra energy capacity they why age the cells prematurely?

p.s. I also only charge my phone to 65% these days because the bigger battery & more efficient hardware allows me to do this without charging it during the day.

 

[DaveinOlyWA]

I could indeed adjust my charge time, which I have set to about ~2 hrs after I depart but also set to "full charge has priority", to maybe about 3 hrs after I really depart. Right now it seems to get me right around 80%. But the battery really should be fine charging to 80%. If Nissan didn't build it well enough to survive my (non harsh, only one QC) charging habits and low mileage, that will be on them to fix it.

I'll update my stats in about a day or two when it is done adjusting.

This isn't a Nissan thing, it's a lithium ion chemistry thing:

https://batteryuniversity.com/index.php/learn/article/how_to_prolong_lithium_based_batteries

The battery will be "fine" at 80% but it will be happier at 75% & even happier at 65%. My point is that if you don't NEED the extra energy capacity they why age the cells prematurely?

p.s. I also only charge my phone to 65% these days because the bigger battery & more efficient hardware allows me to do this without charging it during the day.

Well, I do 75% on the phone which works most of the time. I have wireless charging to extend my charge port life so mine is set to minimize bumps by wire in the car, etc. Occasionally I will go higher but never over 95% for those days where I know my phone won't last the day (4K video seems to really suck up the juice)

 

[lorenfb]

What is yet to be seen is how much the warmer environments hurt the new chemistry.

Right, so no guessing without longitudinal data!

I find it interesting that Tesla will bring up the temp to close to 50C for charging, and leave it above 40 at other times. Those temps would have killed the old Leaf battery, but not sure about the new one.

Naive to compare other battery chemistries with the Leaf's!

 

[lorenfb]

Nissan seems to have come up with a pack that resists heat and cycling degradation,

Really? Where are the data (not anecdotal), please? Some of us with Leaf2s are hoping, though.

 

[DaveinOlyWA]

Nissan seems to have come up with a pack that resists heat and cycling degradation,

Really? Where are the data (not anecdotal), please? Some of us with Leaf2s are hoping, though.

What data do you need? Wish us to collect it for you? How about showing us outliers that do not conform?

This is what I am looking for and have found none. The 40 kwh packs have been in lockstep for rates of degradation and the advantage of the northern tier states is no longer apparent. The disadvantage of the Southern tier states is barely noticable. You know this and you choose to what?

Discount it because its not in a pretty little graph?

 

[danrjones]

This isn't a Nissan thing, it's a lithium ion chemistry thing:

https://batteryuniversity.com/index.php/learn/article/how_to_prolong_lithium_based_batteries

The battery will be "fine" at 80% but it will be happier at 75% & even happier at 65%. My point is that if you don't NEED the extra energy capacity they why age the cells prematurely?

p.s. I also only charge my phone to 65% these days because the bigger battery & more efficient hardware allows me to do this without charging it during the day.

But the warranty *IS* a Nissan thing, and they have to honor it.

 

[DougWantsALeaf]

So to keep the car between 20-60% is ideal?

 

[DaveinOlyWA]

So to keep the car between 20-60% is ideal?

40-45% is ideal. How you manage that is up to you but lucky for us, its rather simple math following two very basic rules.

1) Most important first. Charge to what you need. That means determining how far you need to go plus a buffer while evaluating your willingness to use public charging if needed. Charge to that level.

2) Do not put in what you will not use AKA; "The buffet rule" Now we have all done it. We thought we were really hungry but we weren't. Actually its usually due to the food looking much better than it tastes.

Realize

Degradation is death by a million tiny cuts. IOW; its unavoidable. Pick your battles.

Goal

Limit your cut count to a few hundred grand.

 

[danrjones]

So to keep the car between 20-60% is ideal?

40-45% is ideal. How you manage that is up to you but lucky for us, its rather simple math following two very basic rules.

1) Most important first. Charge to what you need. That means determining how far you need to go plus a buffer while evaluating your willingness to use public charging if needed. Charge to that level.

2) Do not put in what you will not use AKA; "The buffet rule" Now we have all done it. We thought we were really hungry but we weren't. Actually its usually due to the food looking much better than it tastes.

Realize

Degradation is death by a million tiny cuts. IOW; its unavoidable. Pick your battles.

Goal

Limit your cut count to a few hundred grand.

That may all be true; however, Nissan is going to be forced to honor their warranty even if you did charge upto 100% every night and let is sit that way forever. I've looked and that does not void the warranty. Unless you do a few specific things (stupid things like lighting your car on fire, etc), the only thing that disqualify your warranty are TIME and MILES. So the engineer in me says that Nissan should have engineered a pack ASSUMING people would charge to 100% every night in regards to their warranty, otherwise, they are going to be facing a lot of warranty work at their expense. And maybe they did. We do not know yet. Still, if I *HAD* paid full price and 9 months later I had lost 10% of my battery, I'd be pissed at Nissan.

I'd also point out that on this website we have what, maybe a dozen or two examples of 2018 packs and degradation? That's no where near enough data to scientifically determine what is causing the degradation. Mine could be from heat, someone else could be cycles (miles), and someone else could be from leaving it sit at a high state of charge. And all three of us could look like we had the same degeneration, and therefore we ASSUME its time based, when actually it is not at all. I think you would need a lot more samples, in controlled environments, to really be certain. Otherwise is speculative. Which is fine... this is a forum, not a journal of science.

Looks like my pack is almost done adjusting. Hope to have numbers tomorrow.

 

[DaveinOlyWA]

So to keep the car between 20-60% is ideal?

40-45% is ideal. How you manage that is up to you but lucky for us, its rather simple math following two very basic rules.

1) Most important first. Charge to what you need. That means determining how far you need to go plus a buffer while evaluating your willingness to use public charging if needed. Charge to that level.

2) Do not put in what you will not use AKA; "The buffet rule" Now we have all done it. We thought we were really hungry but we weren't. Actually its usually due to the food looking much better than it tastes.

Realize

Degradation is death by a million tiny cuts. IOW; its unavoidable. Pick your battles.

Goal

Limit your cut count to a few hundred grand.

That may all be true; however, Nissan is going to be forced to honor their warranty even if you did charge upto 100% every night and let is sit that way forever. I've looked and that does not void the warranty. Unless you do a few specific things (stupid things like lighting your car on fire, etc), the only thing that disqualify your warranty are TIME and MILES. So the engineer in me says that Nissan should have engineered a pack ASSUMING people would charge to 100% every night in regards to their warranty, otherwise, they are going to be facing a lot of warranty work at their expense. And maybe they did. We do not know yet. Still, if I *HAD* paid full price and 9 months later I had lost 10% of my battery, I'd be pissed at Nissan.

I'd also point out that on this website we have what, maybe a dozen or two examples of 2018 packs and degradation? That's no where near enough data to scientifically determine what is causing the degradation. Mine could be from heat, someone else could be cycles (miles), and someone else could be from leaving it sit at a high state of charge. And all three of us could look like we had the same degeneration, and therefore we ASSUME its time based, when actually it is not at all. I think you would need a lot more samples, in controlled environments, to really be certain. Otherwise is speculative. Which is fine... this is a forum, not a journal of science.

Looks like my pack is almost done adjusting. Hope to have numbers tomorrow.

Yeah sorry. My comments were only directed to keeping as much range as long as possible.

 

[lorenfb]

Nissan seems to have come up with a pack that resists heat and cycling degradation,

Really? Where are the data (not anecdotal), please? Some of us with Leaf2s are hoping, though.

What data do you need? Wish us to collect it for you? How about showing us outliers that do not conform?

This is what I am looking for and have found none. The 40 kwh packs have been in lockstep for rates of degradation and the advantage of the northern tier states is no longer apparent. The disadvantage of the Southern tier states is barely noticable. You know this and you choose to what?

Discount it because its not in a pretty little graph?

It's going to take at least another year of data reporting, e.g. mileage, battery Ahrs, number of QCs, vehicle location, to determine Leaf2's
battery chemistry characteristics.

 

[lorenfb]

I think you would need a lot more samples, in controlled environments, to really be certain. Otherwise is speculative.

That sums it up!