Capacity Loss on 2011-2012 LEAFs

GaslessInSeattle said:

The vast majority of our driving can be done with a 50% charge and as soon as QC's are available, we'll be able to "top off" a lot less, no longer being compelled to charge whenever we can on the off hand chance that we may need to do something unplanned. Over charging is basically caused by precaution due to how slow L2 is, once we have L3, it's going to take the pressure off opportunity charging quite a bit, allowing us to relax more and top off less.

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I believe there is a flaw in your thinking/assumptions. First, not everyone has (or wants) QC. Second, I think it's safe to say that we'll NEVER have L3 (QC) at home, where we DO have L1/L2. In fact, I think that L1/L2 charging (whether it be 3.3kWh or 6.6kWh) is much better for the battery pack long-term.

GaslessInSeattle said:

It's hard to quantify but from what I understand, letting the car sit at a low SOC influences battery life too, which is what the end timer would lead to if the car came home with a lowish battery.

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Yes, I have heard that may be a problem. Looks like the sweet spot would be letting the car go down to 2 bars (around 30% SOC), since the Leaf is delivered from Japan with about 2 bars left (someone else can supply the relevant link to the thread on MNL). Presumably, that is an optimal SOC to leave the Leaf for a period of time. If I get home with 2 full bars, I will wait until a couple of hours before work to start the charging.

I think you have missed my point. I would still do the vast majority of charging at home at L2 speed. Yes, it will take a while for L3 to be everywhere, but I do think it is key to the electrificaiton of the automobile and maybe even be a critical tool in minimizing the number of hours spent at high SOC. I suspect that keeping the SOC high on the off hand chance you may need it is worse than keeping SOC medium and occasionally QCing.

Stanton said:

GaslessInSeattle said:

The vast majority of our driving can be done with a 50% charge and as soon as QC's are available, we'll be able to "top off" a lot less, no longer being compelled to charge whenever we can on the off hand chance that we may need to do something unplanned. Over charging is basically caused by precaution due to how slow L2 is, once we have L3, it's going to take the pressure off opportunity charging quite a bit, allowing us to relax more and top off less.

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I believe there is a flaw in your thinking/assumptions. First, not everyone has (or wants) QC. Second, I think it's safe to say that we'll NEVER have L3 (QC) at home, where we DO have L1/L2. In fact, I think that L1/L2 charging (whether it be 3.3kWh or 6.6kWh) is much better for the battery pack long-term.

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Your sig says you upgraded to MY2012. How and where did that happen? Didn't think MY retrofits were available.

JP

Stoaty said:

the Leaf is delivered from Japan with about 2 bars left (someone else can supply the relevant link to the thread on MNL). Presumably, that is an optimal SOC to leave the Leaf for a period of time. If I get home with 2 full bars, I will wait until a couple of hours before work to start the charging.

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Not true. It's delivered with 50% from the factory.

JPWhite said:

Your sig says you upgraded to MY2012. How and where did that happen? Didn't think MY retrofits were available.

JP

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I think that means traded in a 2011 for a 2012.

TonyWilliams said:

Stoaty said:

the Leaf is delivered from Japan with about 2 bars left (someone else can supply the relevant link to the thread on MNL). Presumably, that is an optimal SOC to leave the Leaf for a period of time. If I get home with 2 full bars, I will wait until a couple of hours before work to start the charging.

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Not true. It's delivered with 50% from the factory.

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Since I don't recall all the details, I looked up the SOC Check Sheet TomT found in his Leaf. You might want to read the original thread as well.

The sheet says that 35% was the standard SOC for shipments out of Japan, and it's probably safe to assume that this is a conservative value for mid to long-term storage. The only remaining question: is Nissan referring to the real SOC or what's indicated on the battery gauge on the dash and in Carwings? I would think that it's the former, and 35% would correspond to four or five bars.

The SOC check sheet itself shows that more than 3 bars are needed before Leafs are loaded onto a ship, but only two bars are needed when the cars arrive at the destination port. What's also interesting, Tom's Leaf apparently was charged to 11 bars before it was shipped and it declined to 6 bars by the time it arrived in Long Beach. Did I get that right? If you discount the driving they had to do when loading and unloading the car in port, that would be fairly high rate of self-discharge.

Tom, are you reading this thread? Would you remember the initial mileage on delivery?

That has a tick in the box for 6 bars at the port of entry. About 50%, as is any LEAF I've seen fresh off the boat (mine included).

TonyWilliams said:

That has a tick in the box for 6 bars at the port of entry. About 50%, as is any LEAF I've seen fresh off the boat (mine included).

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That's good to know, thank you for confirming that! I would think that the battery has received a forming charge at the factory, and the reference to light and A/C makes me wonder if they bring down the SOC manually before the ship leaves Japan.

This would seem to favor the conclusion that 50% puts the least age on the battery. I'm not going to be anal about hitting 50% but I am going to do my best to reduce time at high SOC, even 80% which simply means I'm not going to plug in everywhere I go, every time I get out of the car if the car is going to be sitting for a long time. My guess is that it's shades of gray in both directions from 50% with black being at either end. On the other hand I'm not going to avoid charging to 80 or 100%, i'm just not going to leave the car in that state for long at any one time. Since being charged and ready is a favorable state, I naturally do not leave the car at a low SOC, so no change needed in that habit. seems it may turn out that the battery's life is measured in how many hours/days/years it spends at very low or very high SOC and at what temperature.

TonyWilliams said:

That has a tick in the box for 6 bars at the port of entry. About 50%, as is any LEAF I've seen fresh off the boat (mine included).

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Interesting about the 50% charge on arrival to U.S., new information is always helpful. However, I must disagree about how many bars are represented by 35% SOC, since I go down to 3 bars at around 100 Gids (=35.6%). I wonder if the "standard" of 35% means that is the lowest SOC that is acceptable?

Most lithium-ion cells are shipped and stored at 50%.. not sure about LiFePO4 cells

For me, 80% with end-timer, makes the most sense. Taking it from there to 100% is only about 90 minutes on L2. Waking up 90 minutes before departure isn't all that unreasonable (ymmv ). And, I can start that final charge segment right from bedside with the phone app.

I throw in an occasional timer-override to 100% a bit earlier to allow time for occasional cell rebalancing. Still haven't seen a complete explanation of how that works.

TonyWilliams said:

Where did you get this tidbit?

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The Volt guys have told me that GM is saying 12 years for the Volt battery in AZ and like places and 15 everywhere else.

SanDust said:

TonyWilliams said:

Where did you get this tidbit?

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The Volt guys have told me that GM is saying 12 years for the Volt battery in AZ and like places and 15 everywhere else.

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I really doubt GM would ever admit anything like that.. otherwise you would have seen it in a lot of headlines, and lots of screaming

The biggest advantage of the Volt is that the charge level will not stay high in hot weather, the AC will bring it down to a reasonable level even if the car is parked, within a couple of days IIRC. The cells are insulated in a Volt.

Maybe Nissan can implement a similar thing if it detects the Leaf has been parked for 24 hours at 100%.. it just runs the AC.

Some hard data.

See this post for info on my charging habits. http://www.mynissanleaf.com/viewtopic.php?p=197135#p197135" onclick="window.open(this.href);return false;

When I first got the car (feb 2011) my "gid" value was 280 at 100% charge.
The first bar disappeared at 257

15 months later:
100% charge: 228
first bar disappears: 209

Range on first bar does not seem to be affected. But according to the numbers, I'm overdue for losing a capacity bar as I have 19% loss (a 100% charge will only charge to the original 81% level)

Of course, I have the original firmware. And the new firmware changed the way they display bars significantly. It's been a while, but if I remember right, originally the BMS told the dash how many SOC bars to display and now the VMC does. So YMMV.

Maybe we need a new spreadsheet to track capacity loss...

Herm said:

I really doubt GM would ever admit anything like that.. otherwise you would have seen it in a lot of headlines, and lots of screaming

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Put a few search terms in Google and got this: http://gm-volt.com/forum/archive/index.php/t-10464.html" onclick="window.open(this.href);return false; Seems consistent.

I had dinner sitting next to Andrew Farah. He is the chief engineer for the Volt. One of my many questions was about the useful battery life. He answered with the question of "where". He explained that there is a difference depending on whether you use your Volt in Detroit or Phoenix. These batteries don't like heat. In Detroit's climate he said that we can expect a minimum of 15 years, 12 in Phoenix. He also added that all is not lost as GM is working on a box that can be set in your yard with circuitry to allow your old Volt battery to be used as emergency power for your home.

One of the reasons I did all the firmware updates is because we really don't know what Nissan might have changed in the BMS as part of updates that affects or improves battery management, and how significant those changes, if any, are...

turbo2ltr said:

Of course, I have the original firmware. And the new firmware changed the way they display bars significantly. It's been a while, but if I remember right, originally the BMS told the dash how many SOC bars to display and now the VMC does. So YMMV.

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turbo2ltr said:

See this post for info on my charging habits. http://www.mynissanleaf.com/viewtopic.php?p=197135#p197135" onclick="window.open(this.href);return false;

When I first got the car (feb 2011) my "gid" value was 280 at 100% charge.
The first bar disappeared at 257

15 months later:
100% charge: 228
first bar disappears: 209

Range on first bar does not seem to be affected. But according to the numbers, I'm overdue for losing a capacity bar as I have 19% loss (a 100% charge will only charge to the original 81% level)

Of course, I have the original firmware. And the new firmware changed the way they display bars significantly. It's been a while, but if I remember right, originally the BMS told the dash how many SOC bars to display and now the VMC does. So YMMV.

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Interesting - sure seems that you should have lost a capacity bar by now.

Have you noticed any reduction in range?

My theory for your "charging stopped" followed later by "charging complete" is that you have one or more low capacity cell-pairs that cause charging to stop early, then cell balancing kicks in which allows the car to finish charging. If you are seeing this regularly, I would also guess that these cell-pairs have noticeably higher internal resistance compared to the rest which causes them to go out of balance fairly readily.

Using and end-only timer is a good idea and using 80%/long-life mode is even better.

Have you had your car in yet for the annual battery check? As Tom suggests, I would also get all the firmware updates, too.

Whoa, did I miss something? If I only set the end timer, will the car adjust the start time to finish at the set end time?