Capacity Loss on 2011-2012 LEAFs

[Herm]

While I would like for this to be true I wonder whether an advanced tech battery, and the specialized BMS to properly manage it, will ever be made for retrofitting a LEAF, even at a much higher price.

It wont be that hard to retrofit as long as the replacement use the typical 4.2V lithium-ion cells.. any changes and it gets very complicated. I think the 150 mile packs have a good chance of coming on the market, about 30kWh fitting in the same battery case. Perhaps a cost of $9000 plus labor and old battery exchange once cells get down to $250 per kWh. $7200 for a standard 24kWh pack.

It would not be easy to retrofit the Leaf with lithium titanate or LiFePO4 cells.

 

[leafkabob]

Adding DarkDave.

1. Azdre & Opossum - April 26, 2012. 16.6K miles/13 months ownership. Phoenix (2nd bar loss reported 6/14/2012 @~19K miles)
2. bturner - May 12, 2012. 13.6K/12 months. Phoenix (2nd bar loss reported 7/7/2012)
3. turbo2ltr - May 18, 2012. 13K/15 months. Phoenix (2nd bar loss reported 6/29/2012)
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 (2nd bar loss reported 7/1/2012)
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 (sold that Leaf, replaced w/leased '12 Leaf)
17. ravi100 - June 24, 2012. 13.1K/ 13.5 months. Southlake, Texas (no longer has Leaf)
18. ev4me - approx. June 1, 2012. 7K/ 15 mos. Phoenix (Dropped 2 bars)
19. jspearman - June 28, 2012, ?/10.5 months. Phoenix
20. Leafwing - July 05, 2012, 13.5K/15 months, Plano, TX.
21. GerryAZ - July 05, 2012, ?/?, Phoenix
22. ecoobsessive - July 6, 2012, 13K/13 months, San Antonio, TX
23. jhm614 - May 15, 2012, 25K/14.5 months, Arlington, TX (2nd bar loss reported on 7/7/2012)
24. DarkDave - June 15, 2012. 8.5K/14.5 months. Phoenix

Not reported by owner, but by others:
1. Opossum reported knowing of another car in Phoenix that has 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 (supposedly no longer has Leaf)

 

[TomT]

You're not going to get 150 miles from 30Kwh... If we use the EPA numbers, you'd need twice what the Leaf currently has at the same weight...

I think the 150 mile packs have a good chance of coming on the market, about 30kWh fitting in the same battery case.

 

[kovalb]

I'm a Phoenix driver with about ten months and 14K miles under my LEAF's belt. We still have all 12 bars... knock on wood.

I've read a lot of posts where folks want thermal management, a.k.a. battery cooling. I'm not so sure. I recall that the Tesla Roadster used close to a kilowatt of power when plugged-in in order to cool the battery pack. My car also sits out in the sun at work unplugged for half a day. I wouldn't want the pack sucked dry in order to keep it cool.

My preference would be if a new battery chemistry could be developed that is less sensitive to heat (and cold). As it is I'm pretty impressed at how little heat the current battery generates. Has anyone heard about any such chemistry that has at least reached the lab testing stage?

 

[surfingslovak]

Has anyone heard about any such chemistry that has at least reached the lab testing stage?

You might want to look at A123 Nanophosphate EXT. I'm sure there are other alternatives as well.

 

[RegGuheert]

The point you're missing is that what you're calling "calendar losses" only occur when you don't cycle the battery. They only occur if you overcharge the battery and let it sit for many months or if you overcharge the battery and then keep overcharging the battery for months on end. At 35C. This is more an "either/or" situation rather than an "and" situation since you can't be cycling the batteries and not discharging them.

4.0 Volts per cell is not an "overcharge" condition for any Li-ion cell of which I am aware.

The question becomes: How are the Leaf batteries in Phoenix are being used? Are Leaf drivers charging their cars to 110% and then leaving them in their hot garage over the spring, summer and fall? Or are they using the cars every day and then charging them to 80% or 100% at night? If it's the former then your study offers some insights. If the latter then your study has nothing to offer. What you're calling "cycling losses" is really what happens when the Leaf owners use their Leafs as you'd expect them to.

Agreed that ideally LEAF owners would use an 80% charge on an end timer just before leaving on their 20-mile commute to work, park in a shaded garage at about 60% SOC during the day and then return home and let their LEAF sit in the garage at 40% SOC overnight until the charger kicks in. But I think the reality is that there is a very wide range of use models for the LEAF. Note that a LEAF is typically only driven for about one hour each day or less. The rest of the time it is sitting. At what state of charge? That depends on when it gets charged. It seems clear that some were charging daily to 4.1 Volts per cell and the car was sitting for hours at that SOC.

As for causes of the capacity losses being the same, I quoted your study as describing exactly what these were. That you "seriously doubt" that the side reactions are the same ones that occur with cycling suggests you don't understand the chemistry. Why do you think cycling results in reduced capacity?

Cycling a battery results in a loss of capacity because the primary chemical reactions are not fully reversible. Calendar losses are due to side reactions that occur in the battery regardless of whether or not the battery is cycled.

 

[shrink]

I'm a Phoenix driver with about ten months and 14K miles under my LEAF's belt. We still have all 12 bars... knock on wood.

I've read a lot of posts where folks want thermal management, a.k.a. battery cooling. I'm not so sure. I recall that the Tesla Roadster used close to a kilowatt of power when plugged-in in order to cool the battery pack. My car also sits out in the sun at work unplugged for half a day. I wouldn't want the pack sucked dry in order to keep it cool.

My preference would be if a new battery chemistry could be developed that is less sensitive to heat (and cold). As it is I'm pretty impressed at how little heat the current battery generates. Has anyone heard about any such chemistry that has at least reached the lab testing stage?

Keep us posted, kovalb. I hope your fate is different, but I lost my 1st capacity bar at 10-1/2 months and I think the shortest on the list is 9 months.

RE: TMS - I have a Volt and it doesn't run if the car is unplugged and below a SOC of 75%. The hope, however, is that the battery is cooled overnight when charging, and that the insulation itself makes it more resistant to temperature changes in the ambient heat while sitting unplugged. TMS will run while the car is running, so you do get some cooling on the way home, albeit at the expense of the battery. With a EREV like the Volt, however, it doesn't matter than much. Another option is to remote start the car for a bit during the day so that the TMS can run and cool the battery.

But yes, hopefully the A123 will come to market at a reasonable cost and be all that is advertised.

 

[dhanson865]

Update: full charge overnight went to 265 Gid (94.3%) and took 21.7 kWh from the wall.

Thanks for the data, definitely interesting and useful.

One thing I've wondered for a while is whether or not there's any other proxies for estimating capacity loss without a GID reading.

For example, surfingslovak's range table includes L1 charging time - his chart indicates that the car should estimate 21-22 hours to 100% once you hit LBW, but I know my car was at least an hour short last time I got there.

But going down to LBW or lower is not always convenient - after all, who wants to drive around needlessly wasting energy.

So whenever I need more than 80% charge, I hit the timer-override to charge to 100% about 2 hours before I leave and record the length of time and amount of energy my Blink records before it stops charging. I typically do this about once a month, here's the data I have for the last 6 months (how long I've been recording this):

Jan 2012: 1:28 4.959 kWh
Mar 2012: 1:25 4.667 kWh
Apr 2012: 1:14 ? kWh (Blink crashed, didn't record energy)
May 2012: 1:14 4.379 kWh
Jun 2012 1:13 4.247 kWh
Jul 2012 1:07 3.959 kWh

There's a clear trend here and it certainly looks like I'm down on capacity even though not showing of the impending signs yet. For sure, some of this could simply be caused by the pack being out of balance since I don't let the car sit at 100% for any longer than I need to. Regardless, this is very easy data for Blink owners to collect, even if they normally charge to 100%. Lots of LEAF owners have Blinks out there - would be very interesting to see what someone who's down to 11 bars records as well as anyone else.

Does that mean when the car gets to below 80% battery status the charge to 100% won't do anything different than the charge to 80%?

Would people want a charge to 60% option in that case to avoid fully charging a battery in a hot environment?

 

[DaveEV]

So whenever I need more than 80% charge, I hit the timer-override to charge to 100% about 2 hours before I leave and record the length of time and amount of energy my Blink records before it stops charging. I typically do this about once a month, here's the data I have for the last 6 months (how long I've been recording this):

Jan 2012: 1:28 4.959 kWh
Mar 2012: 1:25 4.667 kWh
Apr 2012: 1:14 ? kWh (Blink crashed, didn't record energy)
May 2012: 1:14 4.379 kWh
Jun 2012 1:13 4.247 kWh
Jul 2012 1:07 3.959 kWh

There's a clear trend here and it certainly looks like I'm down on capacity even though not showing of the impending signs yet.

Does that mean when the car gets to below 80% battery status the charge to 100% won't do anything different than the charge to 80%?

Not sure. That's why I posted my 80-100% charging data in hopes that other people would post theirs since it's so easy to collect so we might be able to draw some conclusions.

Definitely the amount of additional energy I'm getting into the pack between a 80% and 100% charge has diminished in the last 6 months - 1 kWh from the wall is about 3.5 miles of range for me which means I'm getting an 14 additional miles on a 100% charge instead of the 17.5 I was getting in Jan.

Would people want a charge to 60% option in that case to avoid fully charging a battery in a hot environment?

In theory storing the battery at a lower SOC should prolong calendar life. But without actual data it's very difficult to determine at which point one hits the point of diminishing returns. At the very least, it's easy to use an end-timer when charging to reduce time spent at high SOC.

 

[91040]

No. The car goes to 100% or 80% of the battery capacity at the time of charging. If you have 50% of the original capacity, a 100% charge will be that 50% and an 80% charge will be 40% of original capacity. You will still see 12 fuel bars for a 100% charge.

Does that mean when the car gets to below 80% battery status the charge to 100% won't do anything different than the charge to 80%?

Would people want a charge to 60% option in that case to avoid fully charging a battery in a hot environment?

 

[SanDust]

4.0 Volts per cell is not an "overcharge" condition for any Li-ion cell of which I am aware.
...
Agreed that ideally LEAF owners would use an 80% charge on an end timer just before leaving on their 20-mile commute to work, park in a shaded garage at about 60% SOC during the day and then return home and let their LEAF sit in the garage at 40% SOC overnight until the charger kicks in. But I think the reality is that there is a very wide range of use models for the LEAF.
...
Cycling a battery results in a loss of capacity because the primary chemical reactions are not fully reversible. Calendar losses are due to side reactions that occur in the battery regardless of whether or not the battery is cycled.

You picked the voltage which showed a significantly less capacity loss. Ideally you'd charge to under 4.0v. (Isn't that what 80% charging is about?) Companies say that the maximum voltage for batteries is 4.2v but in reality that's an overcharge, a spec that allows consumer electronic companies to claim a higher advertised runtime. (I'm not saying that the Leaf 100% charge is to 4.2v BTW. I don't know.)

It doesn't matter if their use is ideal. For the conclusions of your study to apply they'd have to be fully charging and then leaving their Leafs in the garage for months on end. Leaving their Leaf with a 60% or 79% or 80% SOC should be fine.

Calendar and cycling losses are all due to side reactions. A battery has a limited number of components and there are a finite number of ways to lose capacity. You're confusing cause with effect.

 

[SanDust]

While I would like for this to be true I wonder whether an advanced tech battery, and the specialized BMS to properly manage it, will ever be made for retrofitting a LEAF, even at a much higher price. Perhaps some sort of aftermarket upgrade will become available. But I think $3000 is a pipe dream.

I fervently hope that you are right and I am wrong.

We will never see a retrofit for adding a TMS to current Leafs. Too expensive and impractical. We may see a TMS in the next generation. Or maybe not. It may just be cheaper for for Nissan just to replace the batteries for some vehicles than to add a TMS for all.

I'm not expecting a lot more capacity in the short term. Given that AZ was one of the initial roll out states you have to assume Nissan engineering had some idea of what to expect. My guess is that the surprise has been the reaction to the disappearing capacity bars. They could have left them off, and my guess is that they wish they did.

 

[DaveEV]

(I'm not saying that the Leaf 100% charge is to 4.2v BTW. I don't know.)

100% = 394V which is about 4.1V/cell
80% = 389V which is about 4.05V/cell

Not much different, but cell voltage is pretty flat until you get above "100%" charge which is probably one reason Nissan stops charging there.

Also keep in mind that the lithium chemistry Nissan uses has higher voltage than others so one can't compare voltages directly.

 

[RegGuheert]

1. Azdre & Opossum - April 26, 2012. 16.6K miles/13 months ownership. Phoenix (2nd bar loss reported 6/14/2012 @~19K miles) (8/2/2012)
2. bturner - May 12, 2012. 13.6K/12 months. Phoenix (2nd bar loss reported 7/7/2012) (9/1/2012)
3. turbo2ltr - May 18, 2012. 13K/15 months. Phoenix (2nd bar loss reported 6/29/2012) (8/10/2012)
6. Mark13 - May 22, 2012. 15.7K/12 months. Phoenix (2nd bar loss reported 7/1/2012) (8/10/2012)
23. jhm614 - May 15, 2012, 25K/14.5 months, Arlington, TX (2nd bar loss reported on 7/7/2012) (8/29/2012)

I have added a date in red which shows when these cars would lose their third bar assuming it takes exactly the same number of days it took to lose the second one. Of course no one knows if these cars will lose their third bar before, on, or after these dates and there are many factors which will affect that, including the temperatures in Phoenix and Arlington, but I wanted to make some markers that we could track.

 

[RickS]

Mine goes in on Wednesday to officially start jumping through hoops. :roll:

 

[aqn]

Mine goes in on Wednesday to officially start jumping through hoops. :roll:

may The Farce, I mean, The FORCE, Be With You!

 

[EdmondLeaf]

My guess is that the surprise has been the reaction to the disappearing capacity bars. They could have left them off, and my guess is that they wish they did.

But hard to left off diminishing mileage per charge, as well as power used to recharge from 0 to 100%.
Maybe I am a strange person here, but I can't imagine successful product that everyone wants build by omitting important detail here, hoping that customer will never discover that things are not right. IMO such a product never will be accepted by regular customer. Honesty and trust a key to lasting success.

 

[Boomer23]

My guess is that the surprise has been the reaction to the disappearing capacity bars. They could have left them off, and my guess is that they wish they did.

But hard to left off diminishing mileage per charge, as well as power used to recharge from 0 to 100%.
Maybe I am a strange person here, but I can't imagine successful product that everyone wants build by omitting important detail here, hoping that customer will never discover that things are not right. IMO such a product never will be accepted by regular customer. Honesty and trust a key to lasting success.

I don't know of another recently introduced EV, and admittedly I don't know details on all of them, that has a battery capacity gauge. The Honda Fit EV that I drove, and AFAIK the Ford Focus EV don't have one, and I don't think that the Mitsu or BMW ActiveE or the Tesla S have one either. Those who know better than I, please weigh in here.

I've attached a picture of the dash on the Nissan/Infiniti LE Concept. I'm not sure whether the "fuel" gauge on the far right is a SOC gauge or a capacity gauge, since there is a fuel gauge with a GOM to the right of the temp gauge. So it's not clear whether Nissan intends to include a capacity gauge in the Infiniti EV.

As far as noticing reduced mileage per charge or charging energy required, I think that those are much, much less noticeable to the average driver than a capacity gauge. Some owners who have 70 + mile commutes will notice range reduction right away, but many of us drive that kind of distance infrequently, and driving style and varying energy economy per trip will mask those numbers unless the person keeps pretty close tabs. And most folks don't have a TED, Blink or other means to measure charging energy.

While I applaud Nissan's choice to show capacity on the dash, I agree with SanDust, Nissan may be kicking themselves, or some engineering group, around the HQ building right about now.

 

[DANandNAN]

Because of the limited range I really don't see how it matters whether there's an indicator or not. A 10% drop on a 65-70 mile car is 7 miles. 20% brings it to 14 miles. Loosing 14 miles out of 65-70 is something folks will notice. A long-range Tesla's loss won't be nearly as apparent because most don't drive a few hundred miles before charging very often.

A 20% hit is something that gets noticed - be it mileage, paycheck, or milkshakes :lol:

 

[DaveEV]

I don't know of another recently introduced EV, and admittedly I don't know details on all of them, that has a battery capacity gauge. The Honda Fit EV that I drove, and AFAIK the Ford Focus EV don't have one, and I don't think that the Mitsu or BMW ActiveE or the Tesla S have one either. Those who know better than I, please weigh in here.

Tesla gives you one, but it's slightly obfuscated. The Roadster (and Model S) each have 2 DTE indicators. One that is based on recent driving history and one that is based on "ideal" driving - simulating a constant 55 mph in good weather without HVAC.

The "ideal" driving range gauge is like reading GIDs on the LEAF. Read both after charging stops at a preset and you have a good idea of how much battery capacity has degraded.