Capacity Loss on 2011-2012 LEAFs

[klapauzius]

I'm trying to think what the proper response to that should be.

I guess I would look confused, and then ask: "Are you stupid? Or lying to me?"

I can sympathize very much with this reaction, however, in most cases its a short lived satisfaction, as the same people that you still need
in some form or another hate you now...

 

[leafkabob]

ravi100 said:

Anyway, they printed out a test report and I have called and letf a message on the 800
number to lodge an official complaint.

My question - have all of the 17 owners on the list called Nissan directly on this? If not,
don't you think some concerted action by all of us will elicit a better response than "oh its normal/expected"?

ravi100, I answered you in the "Lost a bar . . . " thread

 

[DesertDenizen]

Pardon my simplistic question. I always charge to 80%. I have had my Leaf here in Tucson for almost a year and am waiting to lose a capacity bar. If/when this occurs, charging to 80% will do what? Charge to 80% of the original capacity or to 80% of the reduced capacity? If the latter, is there still a benefit to limiting charging to 80%?

Thanks.

 

[EdmondLeaf]

You mentioned to me that you not driving this much, therefore I will recommend to charge so you will be back home with 3 full bars. Say, if your trip takes 4 bars than charge to 7. Shallow cycling is very good for the battery so staying in the middle of SOC meter helps. You should avoid going below 3 bars, low SOC is also not good for the battery. This is the best I can answer, maybe other will give you better recommendations.
Wonder if your 9 bar and 80% continue and for how long you have that?

 

[Herm]

Charge to 80% of the original capacity or to 80% of the reduced capacity? If the latter, is there still a benefit to limiting charging to 80%?

80% of the reduced capacity, the voltages wont change, still 394 at full charge even if you have lost 20% of your capacity.. and you should still charge to 80%

 

[DesertDenizen]

Thanks, I can't believe how helpful this forum is.

I have a bit of survivor's guilt. I drive 20-40 miles a day, charge every other day if that, so when I lose a bar it will not really be an issue for me.

 

[EricBayArea]

1. First response - you lost a bar because you haven't charged it fully

2. Second response - it might be because of the "heat wave" we are having

3. Third response - The number of bars can vary due to "conditions" and could come back to 12

Next time someone is at a dealership and they get a response like this (or similar). I would request it to be added to the receipt of service as ACTUAL advice/notes given.

Considering most dealers don't know what's going on, I'm glad that this car is as reliable as it is (all things considered).

 

[JPWhite]

I've both felt sorry for those in Pheonix with the problems heat appears to be having on their LEAF's while at the same time feeling relief my car isn't subject to such brutal heat.

Well intellicast and some other weather services are predicting 108 on Friday in Nashville. If it really gets that hot it will be as high as I have ever seen it in 22 years of living here. And it's not even July.

Looks like we may be joining the club if the weather keeps this up here too. At least it will less easy for Nissan to think of the problem as an isolated incident for few folks in a hot region if the same conditions exist in their back yard.

 

[TurboFroggy]

I would think that a trade off for Nissan to have the pack totally sealed up was no chance of air cooling. My RangerEV has the same pack in it as a Rav4EV. Both are air cooled with a circulation fan and a fresh air fan. I would think that a fan that draws air in from the cabin and then out the pack would go a long ways to cooling off the pack. Maybe have a fresh air intake with a thermostaic door that toggles between the interior and drawing from the exterior depending on which one is coolest.

Living in the Seattle area I am not much concerned about it. I have quick charged 4 times in a row, driving almost 300 miles in one day using the West Coast Green Highway network of charging stations. Just barely got 7 bars that day. 3 QC and 230 miles in another trip resulted in 6 bars (started at 5, went up to 6 just driving.)

I concur about the previous comments about dealers having pre-delivered cars sitting around charged to 100%. I bet this happened not only at the dealers lot but also at the Long Beach terminal as well. I to think that Nissan should have the default charge to 80% and you have to do something to get it to charge to 100%. This is how the charging system works in the Tesla Roadster.

 

[surfingslovak]

I to think that Nissan should have the default charge to 80% and you have to do something to get it to charge to 100%. This is how the charging system works in the Tesla Roadster.

That's a great observation, thanks for sharing! I looked at the Roadster fairly extensively, but didn't realize that standard mode was its default setting. To be fair, Tesla uses slightly higher SOC in that mode than Nissan: it's 87% versus 80%, respectively. Our full charge is about 94% SOC, and Roadster's range mode is 97%.

 

[TickTock]

You mentioned to me that you not driving this much, therefore I will recommend to charge so you will be back home with 3 full bars. Say, if your trip takes 4 bars than charge to 7. Shallow cycling is very good for the battery so staying in the middle of SOC meter helps. You should avoid going below 3 bars, low SOC is also not good for the battery. This is the best I can answer, maybe other will give you better recommendations.
Wonder if your 9 bar and 80% continue and for how long you have that?

I've often wondered if very low charge was as bad as full for storage. Because I have been told to charge to 80% to prolong life, I drive 50 miles rounds trip, and have lost 20% capacity, I always end up at 1 bar when I get home. Because I set the timer to end just before leaving in the morning, it sits in this state for about 10 hours. I wonder if it would be better to charge to 100% so it will be at 3 bars instead of 1 for those 10 idle hours. It would be discharged back down to <80% within an hour of reaching full charge so it seems like sitting at full would have to be A LOT worse (like 10X) for this to be the best strategy.

 

[Stoaty]

I've often wondered if very low charge was as bad as full for storage. Because I have been told to charge to 80% to prolong life, I drive 50 miles rounds trip, and have lost 20% capacity, I always end up at 1 bar when I get home. Because I set the timer to end just before leaving in the morning, it sits in this state for about 10 hours. I wonder if it would be better to charge to 100% so it will be at 3 bars instead of 1 for those 10 idle hours. It would be discharged back down to <80% within an hour of reaching full charge so it seems like sitting at full would have to be A LOT worse (like 10X) for this to be the best strategy.

I don't recall the exact quote, but it was previously stated that lower SOC is better for the battery down to around 30%. The Volt allows the battery to go down to 23% as the lowest allowable SOC. So probably you would have to be lower than 23% SOC to be significantly worried about the effect on the battery. Still, I would agree that charging to a bit higher than 80% might be a better strategy, assuming that the battery pack isn't too hot when this is done and that the time spent at SOC higher than 80% is minimal. If you have a Gid-o-meter, you can get pretty close by assuming 3% gain in Gids per 10 minutes of charge (although I haven't tested above 80%). I routinely use this method now to keep the SOC where I want it rather than just relying on 80% or 100%. This means I can have the car finish charging to just where I want it about 10 minutes before I plan to leave for work. Probably overkill in my climate, but it can get pretty hot in the San Fernando Valley, so I like to have the battery at a lower SOC than I would get with an 80% charge while it is sitting in the hot sun (I generally charge to about 75% and end up at 30-35% when I get home).

 

[KJD]

You mentioned to me that you not driving this much, therefore I will recommend to charge so you will be back home with 3 full bars. Say, if your trip takes 4 bars than charge to 7. Shallow cycling is very good for the battery so staying in the middle of SOC meter helps. You should avoid going below 3 bars, low SOC is also not good for the battery. This is the best I can answer, maybe other will give you better recommendations.
Wonder if your 9 bar and 80% continue and for how long you have that?

I've often wondered if very low charge was as bad as full for storage. Because I have been told to charge to 80% to prolong life, I drive 50 miles rounds trip, and have lost 20% capacity, I always end up at 1 bar when I get home. Because I set the timer to end just before leaving in the morning, it sits in this state for about 10 hours. I wonder if it would be better to charge to 100% so it will be at 3 bars instead of 1 for those 10 idle hours. It would be discharged back down to <80% within an hour of reaching full charge so it seems like sitting at full would have to be A LOT worse (like 10X) for this to be the best strategy.

I think you are correct in this case. Deep discharges can be hard on a battery pack. My charge timer is set to finish 30 minutes before I leave for work, this keeps the time at high SOC to a minimum. In most cases I try and avoid using the bottom 2 bars on the gauge.

In about 5 years I will let you know for sure if this works or not.

 

[surfingslovak]

I think you are correct in this case. Deep discharges can be hard on a battery pack. My charge timer is set to finish 30 minutes before I leave for work, this keeps the time at high SOC to a minimum. In most cases I try and avoid using the bottom 2 bars on the gauge. In about 5 years I will let you know for sure if this works or not.

Indeed. Something to consider: one bar corresponds to a cell voltage of around 3.7V and an SOC in excess of 20%. Certainly, this is signitficantly less than the 40% minimum SOC used in the most conservative cycles, but it's not exactly a deep discharge. Please have a look at the SOC check sheet TomT found in his Leaf. Note that these are old bars, and there substantial reserve below 1 bar now. I would not be worried about leaving the Leaf sitting at one bar. If this was an everyday occurrence, you might want to start with a higher SOC, just as Stoaty suggested.

 

[leafkabob]

After I dropped my 12th bar at the end of May, I asked a co-worker with a leaf if she had all 12 bars. She said she had not checked but did get dinged on her annual battery check for charging to 100% too often. Today she called me and said that she is down to 10 bars! :shock:

I'm adding her to the list under what I think is her forum name. She joined long ago and just lurks, so she wasn't sure if the name is hers either. So if ev4me is actually someone else, let me know and I'll change it.

1. Azdre - Reported bar lost mid April to early May, 2012. 17K miles/14 months ownership. Phoenix
2. bturner - May 12, 2012. 13.6K/12 months. Phoenix
3. turbo2ltr - May 18, 2012. 13K/15 months. Phoenix
4. TickTock - May 20, 2012. 14K/12 months Phoenix
5. Volusiano - May 20, 2012. 16.5K/12 months. Phoenix
6. Mark13 - May 22, 2012. 15.7K/12 months. Phoenix
7. Leafkabob - May 26, 2012. 9.5K/12 months. Phoenix
8. Cyellen - June 7, 2012. 10.2K/ 14 months. Phoenix
9. RickS - June 10, 2012. 11.3K/13 months. Phoenix
10. Pipcecil - June 17, 2012. 20.2K/12 months. Dallas, Texas
11. Phxsmiley - June 17, 2012. 13.7K/10 months. Phoenix
12. AZknauer - June 17, 2012. 9.2K/13.5 months. Phoenix
13. Myleaf - June 19, 2012. 13.3K/14 months. Phoenix
14. johndoe74 - June 5, 2012. 13.5K/ 9 months. Phoenix
15. Matt Ferris - June 20, 2012. 15K/ 12 months. Dallas, Texas
16. Shrink - June 21, 2012. 10.2K/ 10.5 months. Phoenix
17. ravi100 - June 24, 2012. 13.1K/ 13.5 months. Southlake, Texas
18. ev4me - approx. June 1, 2012. 7K/ 15 mos. Phoenix (Dropped 2 bars)



Not reported by owner, but by others:
1. Opossum has reported of two cars in Phoenix that have lost 2 bars.
2. Leafkabob reported a street encounter with a Leaf owner who stated he lost a bar after about a year.
3. Skywagon approx. May, 2012. Phoenix

 

[GaslessInSeattle]

I shoot for 50% for overnight, if that means topping up a bit and then manually stopping the charge, I've been doing it. remembering that there is a hidden bar at the bottom, I generally shoot for 5 bars for long idle times. The consensus seems to be that we have access to nearly the entire true 100% of the battery where as, early on folks were thinking there was a decent buffer at the top and bottom. I would avoid anything below 30%. If I lived in a hot climate, I'd probably find a way to stay a bar or two below 80% max and charge at work too to allow for shallow charging closer to the 50% mark. my guess is that hot whether requires staying even below 80%. I wish Nissan would tell us what they know... having to guess is lame.

You mentioned to me that you not driving this much, therefore I will recommend to charge so you will be back home with 3 full bars. Say, if your trip takes 4 bars than charge to 7. Shallow cycling is very good for the battery so staying in the middle of SOC meter helps. You should avoid going below 3 bars, low SOC is also not good for the battery. This is the best I can answer, maybe other will give you better recommendations.
Wonder if your 9 bar and 80% continue and for how long you have that?

I've often wondered if very low charge was as bad as full for storage. Because I have been told to charge to 80% to prolong life, I drive 50 miles rounds trip, and have lost 20% capacity, I always end up at 1 bar when I get home. Because I set the timer to end just before leaving in the morning, it sits in this state for about 10 hours. I wonder if it would be better to charge to 100% so it will be at 3 bars instead of 1 for those 10 idle hours. It would be discharged back down to <80% within an hour of reaching full charge so it seems like sitting at full would have to be A LOT worse (like 10X) for this to be the best strategy.

 

[Nekota]

I am wondering if there is air flow from the front of the car over the steel case containing the battery pack and exits the open space at the rear of the car when the car is moving and/or the cooling fans are running. Some earlier posts show a fair amount of dust / debris on top of the emergency battery disconnect which could be an indicator of air flow through that channel http://www.mynissanleaf.com/viewtopic.php?f=27&t=8110. If there is room for air flow under the steel battery case in the space between the steel battery case and the fiber panel that covers the bottom of the car then a radiative shield may help reduce the heat load coming from hot pavement? This radiated heat from pavement could be reduced by applying a layer of 'missile wrap' or aluminumized film http://radiantbarrier.reachlocal.com/?scid=2408771&kw=6168299&pub_cr_id=14535620341 to the bottom fiber panel similar to fire walls in some ICE cars having a metalized reflective layer. If there is no air flow, then this radiant barrier may not be a good idea but if the fans do force air through the air space surrounding the steel battery case then maybe the LEAFSCAN could 'turn on the cooling fans' while connected to AC when a cooling temperature difference is present between the ambient air and the internal battery temperature. Maybe a fan can be applied to the 'emergency hatch cover' and move some air over the battery case?

 

[surfingslovak]

The consensus seems to be that we have access to nearly the entire true 100% of the battery where as, early on folks were thinking there was a decent buffer at the top and bottom. I would avoid anything below 30%. If I lived in a hot climate, I'd probably find a way to stay a bar or two below 80% max and charge at work too to allow for shallow charging closer to the 50% mark. my guess is that hot whether requires staying even below 80%. I wish Nissan would tell us what they know... having to guess is lame.

I believe that we have access to about 92% of the total SOC, which is fairly high, but there are other cars that go even higher. The Tesla Roadster might be one of them.

There is a healthy cushion at the top, especially if you only charge to 80%, and an equally healthy cushion at the bottom, if you don't go below the low battery warning. In fact, cycling the battery between 80% and the LBW pretty much emulates what the Volt does with its pack. GM is arguably using a pretty conservative approach there, and their chemistry is similar to ours.

That said, I agree with George that cycling around the middle is both safe and conservative, and you can't go wrong doing that. There is one thing to consider however: 40% SOC could be as good, if not better as your pivot point.

At high SOC, lithium dissolves in electrolyte. This effect is largely neutralized around 3.7V on the cell level, which is somewhere between 20 and 30% SOC. I believe that degradation towards the bottom of the SOC range has a different characteristic; it's about crystalline transitions and changes to the spinel structure of the battery. This effect intensifies around 3V on the cell level, which is well below our turtle mode cutoff.

Finding a balance between these two processes is a relevant concern for storage. Running a shallow cycle has presumably other benefits as well, but it appears that most of the losses we are currently seeing are due to storage and calendar life, and not cycling.

 

[JPWhite]

I would think that a trade off for Nissan to have the pack totally sealed up was no chance of air cooling.

From a cooling perspective I couldn't agree more completely. From a safety perspective however, sealing up the pack makes it very safe, even if a cell/module overheats and vents it will be contained. No fires after the Japanese Tsunami and dozens of LEAF's were crushed.

I agree with Nissan, safety first.

 

[Stoaty]

After I dropped my 12th bar at the end of May, I asked a co-worker with a leaf if she had all 12 bars. She said she had not checked but did get dinged on her annual battery check for charging to 100% too often. Today she called me and said that she is down to 10 bars! :shock:

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