Capacity Loss on 2011-2012 LEAFs

[Boomer23]

So If I set a 6 am end time, I'll probably still leave the car fully charged for a few hours each day before driving it.

Should be ok since its early morning and its cool out.. How cool is it usually at that time?

It's been as warm as 62 and as cool as 58 at 6 am this past week.

 

[Boomer23]

Thanks for the comment. I'll try that. One complication is that I'm on a TOU plan with the best rates being between midnight and 6 am, so I want to get all of my charging done before that end time. And I'm retired, so I don't have an early drive time most mornings (I know, poor me).

OK if you are retired do you really need to charge to 100% every night or can you get by with 80% ?

With a Lithium battery the basic strategy is that you want to minimize the time at the very top SOC and the very bottom SOC as much as possible.

We decided to charge to 100% soon after getting the LEAF, since our usage is somewhat unpredictable. Some days we do want to use the car more than anticipated due to an un-anticipated errand or a spur of the moment trip to the beach for dinner. It's a pain to have to "take the Prius" when you really want to take the LEAF.

We're leasing, so we figured that we wouldn't much care, but now that I'm seeing a small dip in Gids, I care more than I thought I might. We'll have to see if this is a small drop and then a steady plateau at this level, or if the decline continues.

 

[DaveEV]

6/6/11 - 4/8/12, 275-281
Wk of 4/9/12, 271-280
Wk of 4/16/12, 263-276
Wk of 4/23/12, 263-269
Wk of 4/30/12 - 266-271
Wk of 5/7/12 - 262-267
Wk of 5/14/12, 260-265

My last 281 was on 3/26/12.

Seems odd that it would be so stable so long, and decline so relatively rapidly. For those who have owned LEAFs longer, (and had meters then?) how did your gid counts look during this time period last year, as ambient temperatures increased?

+1 - seems very strange that 10+ gids would disappear in a month after remaining stable for a about a year. Does not fit the definition of gradual!

 

[sparky]

I'm also seeing an unusual and abrupt capacity loss, though only about 3%, actually 9 Gids, and of course I haven't lost a capacity bar.

I usually charge to 100% and I've been able to get 281 Gids routinely, with drops down to 278 or so occurring often. But I got a couple of 281 readings early this month. Now, suddenly, I'm only able to get 272 Gids, which reads as 96.7%. I tried charging to 80% for one night, then back to 100% the next night, but still got only 272 at 100%.

I always set a start timer only and leave the J plug in for hours after the charge completion, so there's ample time for balancing.

Boomer, I was seeing some lower numbers (8-9) at 100% charge for a couple of months. But my LEAF has almost never been discharged below 2 bars. I thought perhaps the BMS could use a new reference point so I drove it to VLBW and then charged it to 100%. Since then, the SOC peak numbers have consistently been higher by about 6-8 counts (2%). So, 2% ain't much but it's something you might try.

Other details about my LEAF SOC:
Bought LEAF in Jan '11; ~15kmi; I've been measuring SOC since July '11.
Never seen a 281; 278 was the highest recorded back in July. Usually 275-ish.
I charge to 80% weekdays and 100% weekends. At 80% charge today I recorded a 231.
My last 100% charge was 276.
Because my Blink is unreliable (GFI faults about 1/10 days) I don't do the 100% charge just before driving, as suggested. Blink is still working on this GFI problem a year later.

So, 2x/week it sits for several hours at 100%.
One time when I parked at LAX for a week, I left it plugged in to 120V and forgot that the timer was going to come on Friday and charge to 100%. So, it sat for 4 days in relatively cool weather at 100% SOC. If that did some damage it hasn't yet shown up in the SOC readings.

Battery degradation is a fact of EVs, (like death and taxes); I'm expecting to see something noticeable in the next year. I still love this car and am planning to buy another EV from Nissan, Tesla or whomever meets my priorities in 2014.

 

[aqn]

So far, only from reports in this thread, it's 6-2 "no loss" versus "losing one bar" among higher mileage LEAFs.

 

[JPVLeaf]

So far, only from reports in this thread, it's 6-2 "no loss" versus "losing one bar" among higher mileage LEAFs.

It seems clearer above. But could you please clarify in your wiki entry what you mean by "no loss"? It seems to imply that "no loss" means no loss of a battery capacity BAR, which would be different from "no loss" of battery capacity.

In my case, while I have yet to lose a battery capacity bar, I'm sure I've lost some portion of my battery capacity. For my regular commute route, my upper-Gid (at start) and lower-Gid (at end) levels are decreasing. The amount of Gids used during the route is roughly constant, and the amount of kwh's to bring my battery back to '100%' remains the same. I figure I've lost about 6-8% battery capacity.

Real World Capacity Loss

Other real-world accounts of battery capacity:

Non-loss:
May 18, 2012: 11.5 months, 16,600 miles; charge to 100% 4-5 times/week, quick charged 5-6 times.
May 17, 2012: 16,000 miles, 14 months old, charged to 80% M-Sa, 100% twice on Sundays, "no noticeable loss of capacity".
May 10, 2012: 20,500 miles in one year; "same battery capacity as new".
May 10, 2012: Over 20,000 miles, about one year, "no loss of capacity bars".
May 10, 2012: 10,000 miles in 9 months, "no loss of capacity bars".
May 10, 2012: 19k miles, in one year, "no loss of capacity", "charge to 100% every night. Top off about 70% of the time".

Loss:
May 10, 2012: 13,633 miles in one year, lost one capacity bar: in Phoenix, AZ; charge to 100% every night
1-bar capacity loss after 16624 miles, and the background usage information

 

[Boomer23]

I'm also seeing an unusual and abrupt capacity loss, though only about 3%, actually 9 Gids, and of course I haven't lost a capacity bar.

I usually charge to 100% and I've been able to get 281 Gids routinely, with drops down to 278 or so occurring often. But I got a couple of 281 readings early this month. Now, suddenly, I'm only able to get 272 Gids, which reads as 96.7%. I tried charging to 80% for one night, then back to 100% the next night, but still got only 272 at 100%.

I always set a start timer only and leave the J plug in for hours after the charge completion, so there's ample time for balancing.

Boomer, I was seeing some lower numbers (8-9) at 100% charge for a couple of months. But my LEAF has almost never been discharged below 2 bars. I thought perhaps the BMS could use a new reference point so I drove it to VLBW and then charged it to 100%. Since then, the SOC peak numbers have consistently been higher by about 6-8 counts (2%). So, 2% ain't much but it's something you might try.

Sparky, thanks for the tip and nice to hear from you.

I'm a bit leery of trying a "high-risk" behavior, meaning treating the battery badly, in order to try to fix a problem that I may have caused by charging to 100%, also a not-recommended behavior.

Does anyone else recommend going down to VLBW and then charging to 100% to "jog" things?

 

[turbo2ltr]

I did a "long" drive today, one I do often. 54 miles, 80% freeway at 62-65mph, had 27miles on the GoM and 3 bars when I got home.

I estimated that I was missing about 1 bar, maybe a little less, as compared to what I remember having left over on previous trips. The problem is the bars now are only worth 1.6kWh, and not the full 2kWh, so 3 "current" bars are only 5kWh, where as 4 "original" bars is 8kWh.. at my average of 4kWh/mi, thats a range difference of 32 miles, which sounds like an awful lot. I don't know, to me the math doesn't make sense.



I'm still really finding it hard to get a feel for reading the SOC bars without having all the capacity bars. I relied on the capacity bars heavily to easily know how many SOC bars I already used. Might have to put an overlay on the glass.

 

[aqn]

So far, only from reports in this thread, it's 6-2 "no loss" versus "losing one bar" among higher mileage LEAFs.

It seems clearer above. But could you please clarify in your wiki entry what you mean by "no loss"? It seems to imply that "no loss" means no loss of a battery capacity BAR, which would be different from "no loss" of battery capacity.

It's a wiki. What's in there is no more "mine" than it is "yours". Please feel free to edit.

 

[JPVLeaf]

It's a wiki. What's in there is no more "mine" than it is "yours". Please feel free to edit.

Yes, I'm aware of that. But I wasn't looking for something else to have to edit. Feel free to clarify your entry.

 

[TonyWilliams]

Does anyone else recommend going down to VLBW and then charging to 100% to "jog" things?

No. This sounds like leftover thinking from different battery chemistry. Certainly, you might "never" have to charge to 100% to balance the cells, particularly if you don't use the whole capacity of the battery in your daily jaunts.

I, however, need all the range this battery can deliver virtually every day. Losing many miles of range due to unbalanced cells is just not an option.

 

[mdh]

Does anyone else recommend going down to VLBW and then charging to 100% to "jog" things?

No. This sounds like leftover thinking from different battery chemistry. Certainly, you might "never" have to charge to 100% to balance the cells, particularly if you don't use the whole capacity of the battery in your daily jaunts.

I, however, need all the range this battery can deliver virtually every day. Losing many miles of range due to unbalanced cells is just not an option.

Tony, are yo starting to see any loss? Just wondering.

 

[TonyWilliams]

Does anyone else recommend going down to VLBW and then charging to 100% to "jog" things?

No. This sounds like leftover thinking from different battery chemistry. Certainly, you might "never" have to charge to 100% to balance the cells, particularly if you don't use the whole capacity of the battery in your daily jaunts.

I, however, need all the range this battery can deliver virtually every day. Losing many miles of range due to unbalanced cells is just not an option.

Tony, are yo starting to see any loss? Just wondering.

Well, I'm not hitting 281, if that's what you mean. But nothing like the baked PHX cars.

 

[JPWhite]

Does anyone else recommend going down to VLBW and then charging to 100% to "jog" things?

No. This sounds like leftover thinking from different battery chemistry. Certainly, you might "never" have to charge to 100% to balance the cells, particularly if you don't use the whole capacity of the battery in your daily jaunts.

I, however, need all the range this battery can deliver virtually every day. Losing many miles of range due to unbalanced cells is just not an option.

I typically charge to 80% 100% maybe 2-3 times per month. I was considering eliminating 100% charges altogether unless essential (I like a little extra range on longer trips in case of unexpected diversions or broken public charging stations. I am considering eliminating that buffer). Judging by your comment that might be a retrograde step.

So charging to 100% will balance the cells? Is there a discussion or thread that discusses what is thought to be the optimal charging pattern?

It seems consistently charging to 100% isn't optimal, at least in AZ.

 

[TonyWilliams]

So charging to 100% will balance the cells? Is there a discussion or thread that discusses what is thought to be the optimal charging pattern?

It seems consistently charging to 100% isn't optimal, at least in AZ.

Again, I wouldn't charge to 100% unless I needed it. 100% charge will balance out-of-balance cells after a substantial amount of time after the battery reaches 4.1v per cell.

I have observed over 4 hours after the charge is complete. Keep the car plugged in during this time.

I don't know what is optimal. If the car requires optimum range, I would do it. Otherwise, I wouldn't waste any time letting the battery sit at 100%.

I know lots of folks who always charge to 80%, and then when they wake up, if they need more range for that day, just hit charge from the Internet or iPhone app. When you're done with your morning personal needs, the car should be charged up.(about 90 minutes)?

 

[JPWhite]

When you're done with your morning personal needs, the car should be charged up.(about 90 minutes)?

I did that yesterday, starting the charge from my web browser when I got up. The extra 20% was done in about 58 minutes. Faster than I had anticipated. It only sat at 100% for 30 minutes before I left for the day, taking it down to 3 bars by the end of the outward leg of my journey. Charged back up to 100% at my destination and charged to 80% when I got home.

If I drive carefully and coast down hills etc, I am able to do one leg of the trip on 9 bars pretty consistently. So theoretically I can get away with just 80% charge, but leave myself only 1 bar for diversions, holds ups, extra cooling due to heat etc.

 

[TonyWilliams]

If I drive carefully and coast down hills etc, I am able to do one leg of the trip on 9 bars pretty consistently. So theoretically I can get away with just 80% charge, but leave myself only 1 bar for diversions, holds ups, extra cooling due to heat etc.

I started only charging to 80%, but that got old soon for my range requirements. If you need it, use it. Just try to limit the sitting time at 100% and do whatever it takes to keep the battery out of the brutal heat.

I would not want to quick charge anywhere near the top of the battery capacity in those hot conditions.

 

[surfingslovak]

Does anyone else recommend going down to VLBW and then charging to 100% to "jog" things?

No. This sounds like leftover thinking from different battery chemistry. Certainly, you might "never" have to charge to 100% to balance the cells, particularly if you don't use the whole capacity of the battery in your daily jaunts.

I, however, need all the range this battery can deliver virtually every day. Losing many miles of range due to unbalanced cells is just not an option.

Yes, they say that NiCd had to be cycled deeply, lest you wanted to lose capacity. It's different with lihium ion, where shallow cycles actually extend battery life. I remember reading somewhere however, that it's a good idea to run a deep cycle now and then. Not for the sake of the battery, but for the sake of the electronics. Since things can be a bit fluid when it comes to battery capacity, the software is doing a lot of estimating. It might not be such a bad idea to run a full cycle now and then to get rid of any accumulated errors in those estimates.

Tony, are yo starting to see any loss? Just wondering.

Matt, you might want to review the following thread, if you haven't already:

http://bitly.com/100gidcount" onclick="window.open(this.href);return false;

 

[sparky]

... Not for the sake of the battery, but for the sake of the electronics. Since things can be a bit fluid when it comes to battery capacity, the software is doing a lot of estimating. It might not be such a bad idea to run a full cycle now and then to get rid of any accumulated errors in those estimates.

That was my thinking, not the NiCad memory stuff. I figure if I spend weeks and weeks operating in that constant slope part of the curve it might help the capacity estimator software if I let it "see" the steeper part of the discharge curve down at the VLBW (not to be confused with Turtle, BTW).
I have no other basis for believing this a helpful thing or not. But it seemed to bump up my peak SOC numbers and I noticed the range at the top bar seems better. But, really it's just conjecture and without good physical measurements I might just be imagining any improvement (I see what I want to see).
YMMV!

 

[LEAFfan]

I may lose a capacity bar soon because today, a 100% QC only registered 78% SoC/12 bars. I only had 72%/nine bars after the first charge. I drove 10 miles on the 12th bar @ 45-50mph.