alozzy
Posts: 1169
Joined: Fri Jan 20, 2017 4:25 pm
Delivery Date: 18 Jan 2017
Location: Vancouver, BC
Contact: Website

Re: 2016 SOH versus miles

Fri Oct 12, 2018 5:04 pm

If we were talking about a 2015 LEAF SV (24 kWh pack) at this time last year (for fair comparison), the likelihood of finding a PNW 2015 LEAF, that had already dropped a capacity bar, would be very unlikely.

The fact that @jjgilham has a 2016 SV with an 88% SOH suggests that the 30 kWh packs are indeed worse than the Lizard 24 kWh packs. The PNW climate is ideal for BEVs and should represent best case degradation. The comments of @warrenc, that he found another 1 bar loser, suggest this isn't just a one off...

This is the sort of info that keeps me coming back to these forums. I think it's highly unlikely that my next EV will be a LEAF, as evidence is starting to mount that the 30 kWh and 40 kWh packs are crappy.
Vancouver, CA owner of a 2013 Ocean Blue SV + QC, purchased 01/2017 in WA
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Loving my first BEV :D

LeftieBiker
Posts: 9594
Joined: Wed May 22, 2013 3:17 am
Delivery Date: 31 May 2013
Location: Upstate New York, US

Re: 2016 SOH versus miles

Fri Oct 12, 2018 9:35 pm

Yup, I'm concluding the same - that even if the BMS exaggerates capacity loss in at least some of them, the actual capacity loss for the 30kwh packs is too high. And the 40kwh version (that I have, alas) is at most only slightly better. It's a good thing I only need 90-100 miles of range.
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johnlocke
Posts: 292
Joined: Fri Jan 08, 2016 3:47 pm
Delivery Date: 14 Dec 2015
Leaf Number: 300582

Re: 2016 SOH versus miles

Fri Oct 12, 2018 10:21 pm

If the battery lost 2.5% per year it would meet Nissan's claimed expectations (80% after 8 years or 100K mi.) If the battery lost 4% per year it would barely make the 8 year warranty. Unfortunately for us, the battery degradation in the southwest is more like 10-15% annually. Even in the northern tier states annual battery loss is probably around 5-6%. After 3 1/2 months on a new 30 KWH battery with the LBC firmware upgrade. I'm down about 4% already. If the deterioration slows during the winter as I expect it to, I should be down 6-8% by next June. If it doesn't slow down, I could be down 15% or more by June. The European versions don't seem to have this problem. I'm starting to think that it may be that we drive further and faster than the Europeans particularly in the southwest. Could It be that we are stressing the battery with freeway driving? That could explain why the Japanese cars aren't affected either. Most Europeans and Japanese don't have long commutes and their cities tend to be compact compared to U.S. urban sprawl.

I know that there are cabs in Europe with very high mileage and still have good batteries. Could it be that they rack up all those miles in a low speed urban environment and don't stress the battery with sustained high current draws? Lots of small trips at low speeds instead of long mad dashes at freeway speeds? I'm starting to think that it might have as much to with driving styles as local temps.
2016 SV, New battery at 45K mi.
Jamul, CA
San Diego East County

LeftieBiker
Posts: 9594
Joined: Wed May 22, 2013 3:17 am
Delivery Date: 31 May 2013
Location: Upstate New York, US

Re: 2016 SOH versus miles

Fri Oct 12, 2018 10:39 pm

Could It be that we are stressing the battery with freeway driving?


I'd say no, for two reasons. First, driving 65-70MPh (which I rarely do, BTW) doesn't pull power from the pack fast enough to cause rapid heating. Second, Nissan's "TMS" (passive air cooling) works well ONLY at highway speeds, and should compensate for heating caused by driving faster. I suspect that it's more like Europeans driving a little slower overall, plus driving shorter distances, plus doing less fast charging, plus generally cooler ambient temps.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
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specialgreen
Posts: 141
Joined: Sun Mar 26, 2017 1:21 pm
Delivery Date: 26 Mar 2017
Location: Minnesota

Re: 2016 SOH versus miles

Fri Oct 12, 2018 10:42 pm

6% per year SOH loss doesn't look right to me. I am in Minnesota (which is warmer than Seattle in summer), and my Leaf has degraded 3% over the first 14 months (according to the new BMS firmware). I am driving fewer miles than you (only 7.7k/year) but I've heard that the miles matter less than the number of months, and the weather.
Last edited by specialgreen on Mon Oct 15, 2018 8:34 pm, edited 2 times in total.

johnlocke
Posts: 292
Joined: Fri Jan 08, 2016 3:47 pm
Delivery Date: 14 Dec 2015
Leaf Number: 300582

Re: 2016 SOH versus miles

Fri Oct 12, 2018 11:32 pm

LeftieBiker wrote:
Could It be that we are stressing the battery with freeway driving?


I'd say no, for two reasons. First, driving 65-70MPh (which I rarely do, BTW) doesn't pull power from the pack fast enough to cause rapid heating. Second, Nissan's "TMS" (passive air cooling) works well ONLY at highway speeds, and should compensate for heating caused by driving faster. I suspect that it's more like Europeans driving a little slower overall, plus driving shorter distances, plus doing less fast charging, plus generally cooler ambient temps.

I'm not talking about heating issues here. I'm thinking that sustained high current draws might be damaging to the chemistry instead of heating. It not that the current draw causes a heating effect but rather that sustained high current draws may alter the chemistry in such a way that charging does not fully restore the chemistry. Kind of like sulfation of a lead-acid battery. We know that dendrites form in Li-ion batteries anyway so could a similar mechanism be causing loss of capacity under high current conditions?
2016 SV, New battery at 45K mi.
Jamul, CA
San Diego East County

LeftieBiker
Posts: 9594
Joined: Wed May 22, 2013 3:17 am
Delivery Date: 31 May 2013
Location: Upstate New York, US

Re: 2016 SOH versus miles

Fri Oct 12, 2018 11:56 pm

I'm not talking about heating issues here. I'm thinking that sustained high current draws might be damaging to the chemistry instead of heating. It not that the current draw causes a heating effect but rather that sustained high current draws may alter the chemistry in such a way that charging does not fully restore the chemistry. Kind of like sulfation of a lead-acid battery. We know that dendrites form in Li-ion batteries anyway so could a similar mechanism be causing loss of capacity under high current conditions?


First, the same driving conditions that don't cause heating don't involve sustained high current draws, either. I also doubt that Europeans don't floor the accelerator pedal regularly. Hard acceleration while running a resistance heater, fast charging, hard acceleration up long steep hills, I don't see any of these conditions being significantly less common in Europe. I do think that sustained heating is less common in at least Northern Europe and the entire UK.
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

DaveinOlyWA
Posts: 13281
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Feb 2018
Leaf Number: 314199
Location: Olympia, WA
Contact: Website

Re: 2016 SOH versus miles

Sat Oct 13, 2018 7:24 am

alozzy wrote:The OP lives in Seattle...


I thought he was in NW OR but not a whole lot of difference between the two although OR can and does get a bit warmer in Summer although lately, Seattle is getting plenty warm on its own.
2011 SL; 44,598 miles. 2013 S; 44,840 miles.2016 S30 deceased. 29,413 miles. 2018 S40; 11,987 miles, 485 GIDs, 37.6 kwh 110.89 Ahr , SOH 96.00, Hx 115.22
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jjgilham
Posts: 33
Joined: Mon Oct 07, 2013 8:19 am
Delivery Date: 02 Jun 2016

Re: 2016 SOH versus miles

Tue Oct 16, 2018 9:15 am

Here is the Slope of the SOH curve before the LBC update = 5.8% per 10K miles.

Image



Slope of the SOH curve since the LBC update = 6.6% per 10K miles


Image




Note that the SOH curve for after the LBC update does not have very much data and likely overstates the rate of degradation as it includes August and Sept which are warmer months in Seattle and i think the slope is higher in warmer months.

It appears to me that the rate of degradation may well be unchanged from pre- and post- BC software update. If that is true it might be reasonable to estimate 5% or 6% SOH loss per 10k miles given my driving habits.

If I'm at 88% now it seems like I'll drop 22% in the next 45k miles which would put me at a new battery at 85K miles and 2nd life. I think I'll keep monitoring this and make a determination about what to do at the that last minute before I turn it in or buy it.
2013 SV 3-year lease @ 15k per year
2016 SV 3-year lease @ 15k per year

jjgilham
Posts: 33
Joined: Mon Oct 07, 2013 8:19 am
Delivery Date: 02 Jun 2016

Re: 2016 SOH versus miles

Tue Oct 16, 2018 9:24 am

specialgreen wrote:6% per year SOH loss doesn't look right to me. I am in Minnesota (which is warmer than Seattle in summer), and my Leaf has degraded 3% over the first 14 months (according to the new BMS firmware). I am driving fewer miles than you (only 7.7k/year) but I've heard that the miles matter less than the number of months, and the weather.



Actually, if you just look at the data versus miles driven I'm measuring 5.8% degradation per 10K at 15k miles driven and your experience suggests 3% degradation per 7.7 k miles but that was with the LBC included. My SOH went up 9% post LBC change. Did you notice if yours changed?

You will notice that I didn't include the first 9K miles in my plot because the data was all over the place. I started at 100% SOH and tanked quickly to 93 or 94% and then hovered a bit and climbed back up to 96% from where it began its linear descent that I plotted. I have no idea what to make of that but I assumed it was the BC figuring out the battery. I was not happy that when I checked it at the dealer on Leafspy it was 100% but 1K miles later it was much lower, but what are you going to do?

If you take a look at the complete plot that I put up in a post just below you'll see some strange behavior before 10k Miles. After 10K the behavior is "easy" to understand but not a very happy story. I hope you have better luck in year 2 and year 3 than I have.
Last edited by jjgilham on Tue Oct 16, 2018 10:31 am, edited 1 time in total.
2013 SV 3-year lease @ 15k per year
2016 SV 3-year lease @ 15k per year

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