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Battery degradation on Leaf 40

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8K views 43 replies 10 participants last post by  WesleyNL  
#1 ·
I am looking to buy a Leaf 40 Connecta and wondering what battery % to expect. It is 3yo with around 25000 miles. I am familiar with LeafSpy
 
#2 ·
Fairly typical mileage for a three-year old.

My rough rule of thumb is 5% loss in first year, then 1-2% each year after. So, something like 91%-93% state of health (SOH) for an average three-year old. I wouldn't worry if SOH is a little less that that, but a lot less should, at the very least, be reflected in the asking price.
 
#13 ·
Like others, the reliance and high number of Rapids (QC) would result in higher battery degradation, as against use of fast (L2/1).
Changing to Fast charging should be all accounts slow the rate of degradation, but obviously SOH will not be recovered. For a 2019 of this mileage 91-93 would be more the norm , so only being possibly 2-4% down which is not to worry about.
What is good, in fact near excellent, plus far more important is that all cells appear very even and only 9mv variation.
 
#9 ·
Either the previous owner had no off street parking and no time to spend slow charging, OR it's been used for V2G and every time they plugged in at home logged as a rapid charge.

But regardless, it wouldn't put me off necessarily as long as the battery was behaving and the SoH/mV spread wasn't shocking, which they don't seem to be at first glance.
 
#19 · (Edited)
Very odd usage pattern tbh. It's not exactly a car that a company would give to someone who was bombing up and down the motorway network. And even if it was that kind of scenario, yours still has a vast number of rapid charges. Could be local use I suppose, it's just a very strange pattern of use, I can't think of a feasible explanation other than V2G.
 
#23 · (Edited)
My experience is everything higher than around 5% is bad. I know some people will say this is not true, but we have had a Leaf 40 which we (my wife) used it for a bit more than 4.5 years now. It's going to be replaced this Friday with an EV6 which has twice the battery size but since I have discussed charging habits and battery degradation a lot, and always been declared an idiot because we charge the car to 100% every time she gets home. People claimed that the degradation must be substantially higher than what Nissan service is saying, they can't be trusted and I should check it with Leaf Spy and then I would see the real values. Well, now since we will get rid of the car in a few day's time, I decided to check it, so I bought a dongle yesterday and plugged it in and this is the result:
Image


SOH 94.5% is very good, but to be honest, I didn't expect anything worse because we did not get any indication of anything else. She didn't feel any range degradation compared to when it was new, and if it was not for the small battery size, she would not change the car. Anyway, the car was almost never fast charged, always at home on AC, she drove a total of 39,000km most of it longer round trips (long for the Leaf). This is a Tekna with everything except park pilot pro in it, and she always used the AC and used the car as if it was an ICE, except that she charged it every time she got home. She did not drive the car every day but always needed to keep it at 100% because she never know when she needs to take a longer trip.

Anyway, I think you should need this as reference and try to find a car which is not worse than this one. Make sure that the ODB dongle you are using works with Leaf Spy. I bought one about a week ago and that didn't work, so I bought another one yesterday, which works with the Leaf, but not my BMW i4... so it's a mess, at least if you buy cheap dongles, though the one which works cost me about ÂŁ35 (local no-name brand) so it's not supercheap like one not working, which is a ÂŁ8 version from Amazon.
 
#33 ·
SOH 94.5% is very good, but to be honest, I didn't expect anything worse because we did not get any indication of anything else. She didn't feel any range degradation compared to when it was new,
My car is coming up to 5 years old, although it’s only done just under 20,000 miles. The first four months of its life it was a demonstrator, and a couple of weeks after I got it a cell failed and the battery had to be repaired. Since then it’s mostly been charged with a granny charger, with maybe a dozen or so rapid charges.

I haven’t got (and don’t have the interest to get) Leafspy. I’m still showing ten bars. I also don’t feel that I’ve lost any noticeable range and tried to measure it on a 50 mile (ish) return journey yesterday that I’m doing regularly at present. It’s from Guildford to Morden, mostly on the A3 clearway with a few miles in 20/30mph roads at the ends. The A3 bit is maybe half a 70 limit, where I aim for 60-65 on the speedo depending on uphill or downhill - there are no steep inclines. The rest is 50 or 40 limits which is what I aim for on the speedo. Unfortunately it got a bit messed up by congestion on the way up, so I had about 4 miles at 10-15 mph. It was dark on the return journey but a clear run.

I started with 99% (hadn’t quite finished balancing, I think). GoM was showing 163, which is the sort of level it’s normally shown this time of year. At the end of the return trip of 48 miles I had 68% left and the GoM was showing 109. So while 163 was over-optimistic, the real range seems to still be 155 (48/31 x 100) for this combination of speed and temperature. I can’t really say that’s anything noticeably different from when I first got it.
 
#35 · (Edited)
Please be careful with trusting on the SoH: actually the degradation can be way worse, down into the SoC. Which doesn't show up when you are doing a short test drive, while battery is fully charged. I discovered mine used 40kWh which I bought at 171.000km, has suffered substantial degradation damage by fast charging more then 300times. This discovery I made, after multiple times having experienced that the SoC dropped significantly after reaching 10% SoC. And I had learned, that 0% would be more likely to be 9 or 10% real SoC which can only be seen when using Leafspy. Actually regret, not being able to use Leafspy when I bought it. I trusted the dealership to much, and they even hide for me the fact that it was involved in an accident. That could also cause damage to the battery.

Image


This is how mine 40kWh looks at 17.9% and actually, my car was showing 0% SoC. So that's explained, why my SoC dropped so abruptly around 10% and Leaf Spy then revealed a bunch of weak cell's.

They get balanced out above 20% but below 20% you can find in an early state weak battery cell's, or even bad battery cells. Not sure what's the difference, but having a whole pack of weak cell's means you can't use the full available capacity of the battery pack.

I calculated that if 85% is mine SoH and I can't use 20% of the capacity, then in fact I have a SoH of 68% and I already made my complaints about this. Because based on the capacity bars, my battery should have been totally fine. But it isn't.

From the 32.5kWh that I have in a fully charged battery, I can only use abou 26kWh of it. So that's a big degradation, something Nissan doesn't seem to take into account. With the flawed the design of battery of an Nissan Leaf.

If it wasn't driven fast and charged fast frequently, then I'm sure the state of health would have looked way better. It's the combination of driving fast and fast charging. Driving faster than 90km/h empties the battery quicker, and also heats it more up. In result the battery reaching very highly temperatures when being fast charged.

The battery heats less up when driving slower, and also the range would be bigger: needing less QC's. But considering these Leaf's are mostly driving as a lease, so I'm sure no one driving these Leaf's as they should. They don't need to care about the damage, or the charging costs by the higher electricity consumption.
 
#44 · (Edited)
Well the weakest cell, will decide when Turtle Mode is triggered: that's basically the case. So if you have a lot of weak cell's like me, than around 20% SoC. In the car it will show about 10% and after that, it will start dropping very dramatic to 0% Dash SoC. While in reality it still had 17.9% SoC, as shown by Leafspy.

And then you might see happening that the SoC goes back up again a little: so it's unstable.

Not sure what happened with the Leaf, this Norway youtuber was test driving? But he had the battery almost heated up until the second red bar, and when he wanted to QC for a second time. The car decided to die.


It wouldn't be a bad idea, to run the battery down as much as possible during test driving.

#WesleyNL, your LeafSpy screenshot in your post #35 above (repasted below) shows Hx=71.43%, seeming to confirm the low Hx even though SOH still looks reasonable. In that same post of mine, I show that battery SOH and Hx do not appear to be very dependent on the number of rapid charges, so I would not necessarily blame your 389 QCs for your battery condition. My car has done many more QCs and the battery is fine.

( HX is now 69.28 btw, whatever that number might mean )

View attachment 180812


If you are feeling brave, or that your battery is goosed and you have nothing to lose, and you have half a day to spare, then how about charging slowly to 100%, to get the cells as balanced as you can, then taking a long drive where you take the car at motorway speed to warm up the battery and drain the battery as low as you dare (~10%) and then rapid charge to about 85%, and repeat that a few times until the battery temperature gets up to about 52C (close to the red on the dashboard). Then, next day, once the battery has cooled down, see what the Hx is reading and whether it has made any difference to the performance of the car's range.
No I think it's a combination of fast driving, and also fast charging. One shouldn't think in stereotypes.... but business lease drivers, are usually not the types of drivers who drive 90km/h.

I went to Austria already with this Nissan Leaf, and on the way back I had to do 4 QC's. Still I didn't manage to get it so hot, as in the YouTube video above. But the battery was quite warm, just below the first red stripe.

What I also noticed was, that by driving slower: the battery was able to cool down a little during driving.

Coming Sunday I have to drive 195km and then I would likely again, end up around 10% SoC or lower. And next week Wednesday the same, an appointment at the embassy: so I really will have to fast charge. Because parking is so expensive at the public chargers in Den Haag, that I won't spend more than an hour there.

But anyway I got plenty of long trips planned, and in oktober another roadtrip to Austria. Which I will have to QC charge 3x one the first day, and on the way back the same. Maybe eten 4 times, if it turns out I need a 4th QC.

But basically you are suggesting, to drive om the motorway: at higher speeds? Then go to a QC charger, and charge up to 85% and after that drive it empty at motorway speeds and charge again? I think this will be unavoidable, when I go to Austria in oktober.

Last time I came back from Austria, I had some charging issues: twice at two different charging stations, my AC abruptly stopped. Which is a bit weird, that it happened at two different locations and two different types of charging stations. The only thing similar to them was, that the charging stations allow DC and AC charging.
 
#43 · (Edited)
In this post of mine, I considered whether Hx is a better measure of the condition of the battery, and that batteries that are suffering poor performance show low values for Hx (i.e. below 80%). I also note the apparent correlation between getting the battery hot (or long drives with multiple rapid charges) and a recovery in the value of Hx.

#WesleyNL, your LeafSpy screenshot in your post #35 above (repasted below) shows Hx=71.43%, seeming to confirm the low Hx even though SOH still looks reasonable. In that same post of mine, I show that battery SOH and Hx do not appear to be very dependent on the number of rapid charges, so I would not necessarily blame your 389 QCs for your battery condition. My car has done many more QCs and the battery is fine.

Image



If you are feeling brave, or that your battery is goosed and you have nothing to lose, and you have half a day to spare, then how about charging slowly to 100%, to get the cells as balanced as you can, then taking a long drive where you take the car at motorway speed to warm up the battery and drain the battery as low as you dare (~10%) and then rapid charge to about 85%, and repeat that a few times until the battery temperature gets up to about 52C (close to the red on the dashboard). Then, next day, once the battery has cooled down, see what the Hx is reading and whether it has made any difference to the performance of the car's range.