Post Your Battery Degradation Results

[leafkabob]

I updated a post in this thread dated July 11th. I lost 2% capacity in 1 month am now at 69%. At this rate, looks like October/November replacement. On vacation 2 weeks in September so might not loose 2% in Sept.

I had a 2011 manufactured in April, 2011/delivered late May, 2011. I lost my first bar May 26, 2012 and the second one August 9, 2012. I got rid of the car in January, 2013, but still had not dropped that third bar. I think my uninsulated detached garage played a big part in my capacity loss. It gets really hot in there, especially by late afternoon. I was coming home from work and putting it away in the hottest place possible. Of course I didn't realize at the time that this was a problem.

 

[RonDawg]

As of 6/6/2015:

Two months later SOH is down to 85.97%, Ahr down to 56.96, and HX 73.79%. Gids slightly up at 236, 18.29 kWH, SOC 92.30%.

 

[Evoforce]

I updated a post in this thread dated July 11th. I lost 2% capacity in 1 month am now at 69%. At this rate, looks like October/November replacement. On vacation 2 weeks in September so might not loose 2% in Sept.

Hmmm... On one screen of Leafspy Pro it says 70.1% for SOH, and on the screen where it shows the state of charge for each cell pair, it shows 69% SOH. Which one do I go with? A month ago I only had Leaf Spy Light so I was reading it from the screen where it shows the state of charge for each battery, and it was at 71% but did not show the screen with the GIDs. So on the basis of comparing apples to apples (or same screen to same screen) I lost 2% but if I believe the GIDs pages I'm at 70.1%. Which screen do I go by?

 

[dhanson865]

I updated a post in this thread dated July 11th. I lost 2% capacity in 1 month am now at 69%. At this rate, looks like October/November replacement. On vacation 2 weeks in September so might not loose 2% in Sept.

Hmmm... On one screen of Leafspy Pro it says 70.1% for SOH, and on the screen where it shows the state of charge for each battery, it shows 69% SOH. Which one do I go with? A month ago I only had Leaf Spy Light so I was reading it from the screen where it shows the state of charge for each battery, and it was at 71% but did not show the screen with the GIDs. So on the basis of comparing apples to apples (or same screen to same screen) I lost 2% but if I believe the GIDs pages I'm at 70.1%. Which screen do I go by?

1. there is no "each battery", If you are in the screen with 1-96 on the bottom scale and voltages on the left the 96 items are pairs of cells. This is screen 1 as shown at the bottom left below SOC you'll see a 0 and three white dots.

As you tap that corner the 0 moves to the 2nd, 3rd, 4th position and the others are white dots. Use that to mention the screen number.

2. You need to be sure you are paying attention to units. There is SOC%, SOH%, and GID%.

Screen 1 shows SOC at bottom left and SOH at top

Screen 2 has four subscreens (see text saying tap center: x of 4)

Screen 2-1 doesn't show SOH% (shows voltage histogram)
Screen 2-2 doesn't show SOH% (shows battery temperature sensors)
Screen 2-3 doesn't show SOH% (shows charging power and SOC% and GID%)
Screen 2-4 doesn't show SOH% (shows elevation vs speed graph)

Screen 3 doesn't show SOH% (shows SOC%, kWh, ah, Wh, temp, miles, GIDs)

Screen 4 doesn't show SOH% (shows SOC%, GIDs, Miles remaining, kWh remaining)

So if you are looking at a percentage on any screen other than screen 1 you are looking at something other than SOH.

If you think there is a SOH% on another screen take a screen shot of that screen and post it. On android a screenshot is power button + volume down button at the same time.

 

[NeilBlanchard]

Are there ANY Leafs with a so-called "lizard battery" with noticeable battery degradation?

 

[Evoforce]

It was the GID's percentage that I was confused about, apparently. On page 4 at the very top where is says GID"s and then the percentage to the far right top, I was second guessing that the percentage was for SOH and I was confused why it was slightly different from the first page where SOH is clearly stated.

Thank-you for pointing out that it is percentage of GID's. How is the percentage of GID's helpful?

So my nine bar car is indeed at 69% SOH and has lost 2% in a month.

 

[Evoforce]

Are there ANY Leafs with a so-called "lizard battery" with noticeable battery degradation?

My 12 bar car with Lizard battery installed in Dec, looks to be at 99% SOH at 3000 miles but it is only charging to 87- 89% SOC. It was showing 100% SOH yesterday. But 1% possible loss is not that noticeable.

Edit: 8/25/15

Lizard now at 97% SOH

 

[dhanson865]

Thank-you for pointing out that it is percentage of GID's. How is the percentage of GID's helpful?

SOC% is relative to the maximum charge which becomes smaller over time. Starting a trip at 80% SOC and ending at 60% SOC one year might be 20% now but doing the same trip next year might be 80% to 58% for 22% difference.

GIDs are absolute. If a trip uses 20 GIDs this year it'll be 20 GIDs next year even after your SOH% drops. But gids aren't a unit people are used to and aren't base 10 so for convenience people prefer to deal in % instead of actual GID units.

I use SOC% myself and am willing to adjust over time. I've got Leafspy logs that tell me energy used on past trips and I have Leafspy/GOM/evtriplanner/google maps plus my own m/kwh or whatever to figure it out.

So far I've never been able to charge higher than 92.9/93% and often it will stop in the low to mid 92.x range. Practically you can use the bottom few percent. So to me the SOC% seems pretty goofy/arbitrary anyway. I mentally think of it as 92% SOC = full and 8% SOC = empty but really if leafspy says I have range left I don't worry and keep driving. I've never hit turtle but I do hit VLBW from time to time.

if you want to be detailed and compare your trip to mine we need to compare trips in kWh or GIDs to avoid the variability of SOC.

 

[Stanton]

I updated a post in this thread dated July 11th. I lost 2% capacity in 1 month am now at 69%. At this rate, looks like October/November replacement. On vacation 2 weeks in September so might not loose 2% in Sept.

Remember that trajectory is only valid for high temps; as temps fall off, so will your degradation. In fact, I can pretty much guarantee that by the time you get back from your vacation, it will have slowed (besides missing the miles for those weeks). That's why I'm doing everything I can to "make hay" while the temps are hot: I've got about 2 AHr to go before I drop my 4th capacity bar.

 

[mwalsh]

I updated a post in this thread dated July 11th. I lost 2% capacity in 1 month am now at 69%. At this rate, looks like October/November replacement. On vacation 2 weeks in September so might not loose 2% in Sept.

Remember that trajectory is only valid for high temps; as temps fall off, so will your degradation.

I managed to drop 0.30AHr over the last week with lower than average temperatures in SoCal; only 25 miles of driving; and a single charge cycle! Down to 43.70Ahr as of today.

 

[Stanton]

I managed to drop 0.30AHr over the last week with lower than average temperatures in SoCal; only 25 miles of driving; and a single charge cycle! Down to 43.70Ahr as of today.

You are getting very close to dropping that fourth bar! I dropped about .30 AHr this week as well, but it has been very hot here. To be honest, it seems to drop in "chunks" of .05-.10 AHr, and usually around a charging event.

 

[Evoforce]

Well... I did some digging and found out some stats on 9 bar car. It stacks up like this:

Manufacture Date - 4/14/11

Purchased Dealer Inventory - 5/27/11

Retail Purchase Date - 9/3/11

Retail Date - 9/3/11

Delivery Date - 9/10/11
**********************************************************************

When I purchased the car 2/28/15 was * 10 bars * and from California

Car is at 71% SOH on 7/11/15

Car is at 69% SOH on 8/12/15 and * 9 bars * it looks like I have just shy of 13 months to qualify for warranty. Wow! I'm glad I have the extra time. Now we will see what happens. Based on the stats, It looks like it will be a capacity warranty car. Feeling a little more unlucky which actually makes me feel more lucky. Very strange mix of emotions! Yes, very strange...

Edit: Car is at 68% SOH @ 45.11Ahr on 8/15/15

Edit: Car is at 67% SOH on 9/7/15

Edit: Car is at 65% SOH on 10/9/15

Edit: Car is at 63% SOH @ 41.79Ahr on 11/25/15 and qualified * 8 bar * for new battery and still remained at 63% SOH until new battery install on 1/20/16

 

[Valdemar]

I managed to drop 0.30AHr over the last week with lower than average temperatures in SoCal; only 25 miles of driving; and a single charge cycle! Down to 43.70Ahr as of today.

Ha, mine dropped almost 0.77AHr from just sitting in a more or less insulated garage for 2 weeks at 60% SOC. This is a capture from yesterday at like 20 Gids, what's interesting is that weak cells are clustered together, probably has something to do with how temperature is typically distributed across modules. Wondering if opening the pack and rearranging modules may help to prolong useful life a bit.

 

[DaveEV]

This is a capture from yesterday at like 20 Gids, what's interesting is that weak cells are clustered together, probably has something to do with how temperature is typically distributed across modules. Wondering if opening the pack and rearranging modules may help to prolong useful life a bit.

I've seen similar imbalances at lower SOCs before. I'll try to get some screenshots from LEAF Spy next time I'm down near VLBW.

 

[RegGuheert]

This is a capture from yesterday at like 20 Gids, what's interesting is that weak cells are clustered together, probably has something to do with how temperature is typically distributed across modules.

Cell-pairs 1-48 are in the 24 modules stacked (horizontally) beneath the rear seat. Just as you say, you can see the temperature distribution across that pack directly in your degradation curve: The hottest modules contain the cells around the center (24-25) and the modules are cooler as you approach the outer edges of the pack (cells 1 and 48).

Wondering if opening the pack and rearranging modules may help to prolong useful life a bit.

I've had exactly that same thought: Module rotation to extend battery life? But I think rotation would be better done earlier in the life of the battery. Too bad it's so difficult to do. As Li-ion batteries get longer-lived, I wonder if some might actually do this.

 

[Valdemar]

But I think rotation would be better done earlier in the life of the battery.

Yeah, the damage is already done.

 

[Evoforce]

If I were to be in your shoes, I would rotate in some good used cells. Then I would put in a bilge blower and a vent for the pack in the engine compartment and protect it so it doesn't ingest water, debris, etc.. I don't know if you have the tools etc. to do this.

 

[Valdemar]

If I were to be in your shoes, I would rotate in some good used cells. Then I would put in a bilge blower and a vent for the pack in the engine compartment and protect it so it doesn't ingest water, debris, etc.. I don't know if you have the tools etc. to do this.

The problem is finding good used cells, the best bet would be finding a donor 11/12 pack from a wrecked Leaf, but you'd buying a pig in a poke. I doubt 2013+ modules can be used in 11/12 packs. Then spend several days swapping modules, removing/reinstalling the battery. Too much trouble for limited benefit in the best case. My fix will likely be a new pack purchase 2-3 years down the road.

 

[Stanton]

Ha, mine dropped almost 0.77AHr from just sitting in a more or less insulated garage for 2 weeks at 60% SOC.

How can I get in on some of that action! I need to drop about 2 AHr (I'm at 45+) to drop my 4th bar, and I thought the extreme heat (100+ degrees) the last week or so would accelerate things. I'm doing my best to "charge hot", but I've only dropped about .3 AHr in a week; had a nice surprise yesterday though (about .05 in a day). I'm looking for some non-linear drops!

 

[Valdemar]

Dropped additional 0.33AHr, currently at 43.97, at this rate I'll loose the 4th bar sooner than expected but still too late to get a replacement. With the $10k off available from NMAC, 0% financing and VPP pricing a new car does look a better option than dealing with reduced range and paying for replacement 2-3 years down the road.