Battery Degradation of a high mileage Leaf

[Chad E. Mo]

... bollocks that you would have only 5% battery degradation with a 2019...

Maybe not...
I do not baby my 2020, and I have less than 10% degradation.

 

[Oostenrijker]

Maybe not...
I do not baby my 2020, and I have less than 10% degradation.

That's a 2020 ,( also its a 62kWh ) and not a 2019: EV's have battery degradation, due to age as well. So obviously, a 2020 would have lesser degradation then a 2019 if threatened similar.

But anyway: that's close to 10% degradation. Actually I don't look at those numbers anymore.... I saw my SoH of the previous Leaf go up, and later it dropped in the winter again.

For my mental health, its the best not to look at Leafspy frequently.

 

[GTH]

I'm sorry to say so: but you are fooling yourself. You can't measure degradation like that, and it's bollocks that you would have only 5% battery degradation with a 2019...

If you haven't checked it in Leafspy, then it's no more then guesses: and your driving skills might have improved over the years, which maybe makes that you are driving more energy efficient now?

My current 2019 Leaf has a SoH of about 90% and the GoM showed 273km of range the other days at 100% SoC. After 100km of driving, my SoC was 72% and my energy consumption was 9.77kWh/100km.

But if I didn't tell my consumption: then people would think? Ow your Leaf is still able to drive 270km on a full charge... only the fact is, I was hypermiling the **** out of that day. So that I had enough juice, to get back home after returning with the airplane.

Interesting! I will buy LeafSpy and adaptor and get back. However my driving techniques have not changed and my long trips each year do seem to show little degradation. I will get back next week.

 

[Oostenrijker]

Interesting! I will buy LeafSpy and adaptor and get back. However my driving techniques have not changed and my long trips each year do seem to show little degradation. I will get back next week.

Even if your driving techniques haven't changed: your tires are wearing off, so that means less rolling resistance. Which actually results in a lower energy consumption.

My previous car was a Suzuki Celerio: when I bought it used, it had energy efficiency summer tires which where wore off and had still between 3mm and 4mm profile left.

I replaced those, by four seasons tires from Nexen: which had a worse energy label, and yes my consumption went up. Later after driving more than 50.000km with those tires, my consumption was down again.

Actually I drove almost 4 years with those tires, and I kept track of the gasoline consumption. So whenever an EV owner tells me, his battery pack has no degradation? Then I think that's bollocks.

Even if you can still use the same amount of kWh's: if a manufacturer places a 50kWh battery pack, but only 40kWh net is available? Then yes, most likely you won't notice a thing. But the battery pack is still degrading.

The Leaf has a very small buffer: from the 40kWh, you can use new 39kWh new in the summer. Funny thing is though, the BMS determines how much you can use. So in the winter, I noticed the Leafspy SoC was 93% whereas in the summer it would be 97% Leafspy SoC.


My guess is: my current Leaf, has a net of 35kWh still available, under optimal conditions. If you wanna do a degradation test by yourself? Without professional tools? Remember, my Leaf was show in AutoWeek Accudegradatietest. I had a device connected to my ODB2 port, which kept track of all the data.

But if you don't wanna do that: either use Leafspy: mark down how much kWh's is available when fully charged, and then drive to ---% and see how much you used? That's how I discovered, my previous Leaf was hiding plenty of leftover energy. But simply couldn't use it, due to so many weak cells.

One thing you can do is: reset the board computer. You will be able to roughly calculate, how much kWh's you still have in your pack. Without showing the reserve, which would be between 3kWh and 5kWh.



So the other day I left with 100% dash SoC: drove 261km return trip. We went to an attraction park, which was lacking public chargers. I arrived there with 49% back, and on the way back I completely avoided the highways. And was hypermiling the sh*t out it.

I made it home, with ---% and my average consumption was 11.8kWh/100km. With this number, its easy to calculate how much I actually used. Although I can just check the really bad Nissan EV app, when it works...



It shows I used 30kWh and I regained almost 4kWh, so the total energy consumption was 34kWh. But that 4kWh, I gained back. So that means, I had 30kWh available on that specific day. Probably about 3kWh a 5kWh reserve, so I would have between 33kWh and 35kWh net left. This was in spring, as said: in summer their is more energy available.

The BMS would increase it buffer.

 

[GaleHawkins]

Hi all,

I also bought a Nissan Leaf Tekna from 2019 in January 2020.

Time based degradation is not true for me! I don't (yet) have a LeafSpy
so can only use the BMS readouts. My car is now 4.25 years old and I am
convinced I have not lost more than 5% at most and probably a lot less.
This is properly checked on a long trip of 160 miles each year. Always
a summer trip and mostly at 50mph, so near the optimum. Nissan quote
239 miles at 50mph and 20 degC for my 62.5kWh battery.

After 160 miles the BMS said I had used:
68% in 2021 at car age 1.5 years (air temp 21 degC)
72% in 2022 at car age 2.5 years (air temp 18 degC - below optimum)
68% in 2023 at car age 3.5 years (air temp 25 degC)

Recently with temperatures around 18 degC I used 33% for 80 miles but
this is at a mix of speeds on local roads which compensates for the
slightly below optimum temperature.

In all cases I am still very close to the 239 miles quoted for 100%.

To be fair I do always drive for maximum range - I normally avoid using
more than 3 bars when accelerating but at this level I can keep up with
all normal drivers. On dual carriageways I try to restrict my speed to
the low 60s (mph) unless this causes issues with any other road users.

The rest is down to very carefully researched battery care as follows:

1) NO high speed charging ever (so far!)- I use 13A sockets always.
This avoids damage due to excessive battery temperatures.

2) ALWAYS charge to 100%, roughly once a week at home but more on
holiday. This ensures good cell balancing which is very important.

3) NEVER leave the SOC above 80%. I charge overnight and drive down to
90% or lower but then always down again to under 80% on the second day.

4) NEVER go below 25% SOC but if I get below 50% always charge back immediately to nearer 80%. This avoids risk of any weak cell damage.

The critical concerns to avoid are high battery temperatures from repeated fast charging and never leaving the SOC below 50% or above 80% for any length of time as different degradations occur under long term low or high charge. I was fortunate that, when Covid lockdowns hit, my SOC was around 80% and not above!

Whether this continued care will maintain my battery life long term I
will only find out in future years but so far it seems to be working.
My next test will be later this year when I do my 160 miles trip again.

That is a good detail report with positive results. From my experience it seems like the battery technology matured for the 2018 and up Leafs. I have a 2016 SL with a 2020 new 40 kWh battery. I was going to sell it when I got the 2023 Tesla model y long range but the battery health is staying up well. Plus the wife drives it about once a week to work and so I'm just going to hang on to it cuz I only have S13.5K in it and it's a backup EV if I'm out of town with the Tesla etc. if it gets totaled again like it did 8 months after getting the new battery I'm just going to try to buy it back and pull the battery out of it maybe for a solar system. It has been charged at home all except for about 10 minutes when I did a fast charge just to test to make sure the new charging connector worked fine.

 

[DaveinOlyWA]

Hi all,

I also bought a Nissan Leaf Tekna from 2019 in January 2020.

Time based degradation is not true for me! I don't (yet) have a LeafSpy
so can only use the BMS readouts. My car is now 4.25 years old and I am
convinced I have not lost more than 5% at most and probably a lot less.
This is properly checked on a long trip of 160 miles each year. Always
a summer trip and mostly at 50mph, so near the optimum. Nissan quote
239 miles at 50mph and 20 degC for my 62.5kWh battery.

After 160 miles the BMS said I had used:
68% in 2021 at car age 1.5 years (air temp 21 degC)
72% in 2022 at car age 2.5 years (air temp 18 degC - below optimum)
68% in 2023 at car age 3.5 years (air temp 25 degC)

Recently with temperatures around 18 degC I used 33% for 80 miles but
this is at a mix of speeds on local roads which compensates for the
slightly below optimum temperature.

In all cases I am still very close to the 239 miles quoted for 100%.

To be fair I do always drive for maximum range - I normally avoid using
more than 3 bars when accelerating but at this level I can keep up with
all normal drivers. On dual carriageways I try to restrict my speed to
the low 60s (mph) unless this causes issues with any other road users.

The rest is down to very carefully researched battery care as follows:

1) NO high speed charging ever (so far!)- I use 13A sockets always.
This avoids damage due to excessive battery temperatures.

2) ALWAYS charge to 100%, roughly once a week at home but more on
holiday. This ensures good cell balancing which is very important.

3) NEVER leave the SOC above 80%. I charge overnight and drive down to
90% or lower but then always down again to under 80% on the second day.

4) NEVER go below 25% SOC but if I get below 50% always charge back immediately to nearer 80%. This avoids risk of any weak cell damage.

The critical concerns to avoid are high battery temperatures from repeated fast charging and never leaving the SOC below 50% or above 80% for any length of time as different degradations occur under long term low or high charge. I was fortunate that, when Covid lockdowns hit, my SOC was around 80% and not above!

Whether this continued care will maintain my battery life long term I
will only find out in future years but so far it seems to be working.
My next test will be later this year when I do my 160 miles trip again.

1) The detrimental effects of high speed charging is frequently misunderstood and your example is spot on... High speed charging used responsibly has never been proven to increase degradation

2) Charging to a high SOC w/o a valid reason is VERY bad advice. Cell balancing simply does not provide the level of benefit that will overcome advanced rates of degradation of high SOC. Charging to full should only be done in preparation for a day where it needed.

3) Lithium prefers life in the middle as much as possible. Because transpo is so required in our lives, managing this can be a challenge. You have chosen to ignore this with a single charge covering what appears to be SEVERAL days of use. You couldn't possibly be doing it more wrong.

4) The dash is not accurate so your 25% is closer to 35% so yeah good advice, bad numbers and FYI; 80% is not a golden level. It is simply a marketing tool to allay range anxiety fears. 50% is what you should covet.

 

[Oostenrijker]

Just charge around 25% a 30% to 65% a max 80% dash SoC: that's what I do, because I can't charge at home. So I charge while doing shopping, that gains me a SoC of about 55% a 60% after finishing shopping.

I just keep my dash SoC between 25% and 65% when not needing more range: its more convenient, to plug in while shopping. Because the EV charging spots are further away, from the normal parking spots. So the risk of damages to my car is almost zero.

 

[GTH]

It has taken some time to get LeafSpy and a dongle working! I first bought a LELink^2 and that just would not connect to my newish Samsung Galaxy XCover6 Pro. So I bought the VeePeak Mini Bluetooth VP11 with its standard Bluetooth (non LE) from Amazon and despite forum messages to the contrary it now works absolutely perfectly, but only after solving the same connection problem:

The issue (made obvious by the standard Bluetooth pairing of the VP11) is that I had to disconnect my phone from the car first, link to the VP11 and then add the car bluetooth back in! I did have to tell the car I wanted to use 2 phones or else it would not link to my phone! This must be a Bluetooth channel clash. Setting the car for 2 phones allows it to try different channels presumably. I had tried both channel 1 and 16 for the dongle before but doing the dongle first worked. Now I find the LELink^2 also works perfectly with no need to change the phone/car linking!

Anyway I now know my car has SOH of 94.72 which is very close to my estimate of 95%. I am also delighted with the excellent high Hx factor. I agree this slight degradation can be swamped by other factors like tyre wear, very slight mileage differences in my trip each year, air temperature etc etc. I knew it is thus almost impossible to prove but even LeafSpy uses estimates and unknown calculations which are not all consistent. So I am pleased that my estimate was close to what LeafSpy says and I am now absolutely sure I have NOT suffered the quoted 11% loss though to be fair this figure is not agreed by lots of other forum members either!

As for comments about my charging to 100% not being good, that is just not true taking it without further qualifying details. The real risk factor is the combination of 100% charge, length of time and temperature (so OK in a cold winter) but as I have said I only ever charge over-night and always get it down to 90% or more usually 80% early next day after being at 100% for only a very few hours which is perfect according to loads of research papers. As for cell balancing. I accept that it may be active during lower SOC charges but it can only be truly effective at 100%. I know my charge rate often drops for the last hour or more when charging to 100%. At this low charge rate the shunts can stop good cells from charging but the weak cells get a trickle charge - the shunts could not cope with more. So true balancing is only done at 100% with a longish period of very low charge rate - this can never happen at lower SOCs due to the high charge rate. I am sure the shunts may be operating but their effect while doing a full rate charge will be minimal.

So I will stop here as I am up against people with very strong views which I believe equally strongly are wrong. I am attaching a graph taken today:

Just for interest I am also including another almost identical graph but with many of the blue and red bars reversed! This seems to make nonsense of the colour relating to shunts? Does anyone actually know what the red and blue mean? Each time the car is scanned you get a different combination of red and blue and slightly different variation in cell differences, maybe it is due to random shunt switching?

 

[Oostenrijker]

Maybe 62kWh have lesser degradation? Considering, it will have fewer charging cycles? I have a 40kWh, so for driving the same distance as you. Means I would have to charge more.

Anyway I was really interested in getting a 62kWh Leaf, but that wasn't a option.

 

[DaveinOlyWA]

Maybe 62kWh have lesser degradation? Considering, it will have fewer charging cycles? I have a 40kWh, so for driving the same distance as you. Means I would have to charge more.

Anyway I was really interested in getting a 62kWh Leaf, but that wasn't a option.

Its not about charge cycles, its about SOC management. The closer you remain in the center SOC range, the better. Longer range EVs make this easy as their center SOC range can drive further.

 

[Oostenrijker]

Its not about charge cycles, its about SOC management. The closer you remain in the center SOC range, the better. Longer range EVs make this easy as their center SOC range can drive further.

I remain a lot between 25% and max 80% and I tend not to charge until 80% at all, because its to frustrating to do so.



It would say: that it takes 6.5 hours to charge until 80% totally, but I have the experience that it actually might have faster or slower? Nevertheless, there isn't a option to stop the charging at exactly 80%

So now I have setup a timer: to see if it works with a public charger as well, to start at 2am and end at 7:30am when I would leave to work.



My current Leaf, was showing a range of 302km this morning and actually I think that it would be quite likely to also be able to drive this KM's if one avoids the highway complete.

 

[bruceha2000]

Is there a degradation curve somewhere? 2020 SV Plus with 88K miles. Original range (summer) 215 miles, now 195 miles. Wife drives it a minimum of 75 miles 7 days a week. Charged overnight at home on L2. I'm curious if the curve is a straight line over time or curved and either increases or decreases over time.

 

[DougWantsALeaf]

Here are our 2 2019 Plus Leafs curves. Red one is primarily DC charged, and blue one is primal home L2 charged.

 

[nlspace]

The curves look nearly identical once you take into account the shift for time dilation.

 

[bruceha2000]

The step ups are interesting. What would cause that? And is it expected that a battery primarily DC fast charged would degrade less than one charged on L2? The flat line over the last year on the L2 charged car is encouraging.

 

[DougWantsALeaf]

The readjusted SoH which happens every quarter can move the SoH up or down a couple%. Not sure exactly why that is the way it is. Both cars had a ~2 year period with basically 0 net loss.

I measure less frequently now.

 

[DaveinOlyWA]

The step ups are interesting. What would cause that? And is it expected that a battery primarily DC fast charged would degrade less than one charged on L2? The flat line over the last year on the L2 charged car is encouraging.

Nissan BMS manipulation. Why? Nissan has said nada on the subject and doesn't even acknowledge the event exists. But it happens every 3 months (determined by manufactured date) and SOH can go up, down or stay the same. Started with Gen 2 packs.

My theory is Nissan's attempt to preserve battery longevity by manipulating a top end hidden reserve. Nothing else really makes sense

 

[DougWantsALeaf]

Thats my guess too, it widens or shrinks the buffer based on some basic battery metrics like max temp or tike at high SoC.

 

[DaveinOlyWA]

The readjusted SoH which happens every quarter can move the SoH up or down a couple%. Not sure exactly why that is the way it is. Both cars had a ~2 year period with basically 0 net loss.

I measure less frequently now.

I used to measure daily, its now once a week with the only exception being the week of the adjustment and yeah after 22 adjustments, I do know when they are coming

 

[Oostenrijker]

I used to measure daily, its now once a week with the only exception being the week of the adjustment and yeah after 22 adjustments, I do know when they are coming

I never look at it: makes one crazy when doing so.