Turning Over a New LEAF: My Response to a Lost Capacity Bar

[azdre]

Can your issue wait 6 months? now, there is no guarantee Nissan will do anything in 6 months but then again, i cant see them just letting it go either

The answer is maybe. At this point, my 100% range with conservative 5.0 mi/kWh driving to LBW is about 58 miles, 6 months ago, it was 80 miles. Commute is 40, gym is another 20, lunch is usually 5. I'm already unable to drive routes that I had absolutely no issue with 6 months ago. It's not a showstopper yet, but I may only be a few months away from needing to get another hybrid just so opossum and I can both get to work and back on the same day. I HATE the idea of going back to an ICE, but I may not have a choice until I can save up a few bucks for my Model S (assuming those stand the test of time).

There are also a few problems with shutting up and waiting. If no one demands that this be addressed, why would it ever be addressed, in 1 month, 2 months, 6 months? I LOVE this car, it is extremely well-built, comfortable, and fun to drive. I expected glitches, issues, etc. but I also expected Nissan's published expectations (poor sentence, but it's late and I'm struggling to come up with better words) to come in within the ballpark. 70-80% in 5 years... AWESOME. 70% in 4 years, ok, obviously something was unknown and risk is there. 70% in 1.2 years is utterly outrageous and significantly outside of the expectation, advertisements, EPA ratings, etc.

Also, waiting to see what happens will put a lot of us outside of our lemon law protection (what little there is in this situation).

They did know that high heat could be detrimental to the vehicle, as it is for all vehicles.
...
I do doubt that Nissan knew this was an issue

They did or didn't know?... Anyway... When asked about battery performance and warranty, Mark Perry very specifically cited Phoenix, Arizona as a place where we should not be concerned about parking our car outside on a hot day. If he did know, he lied. If he didn't know, this is poor engineering or manufacturing. Either way, it's not the consumer that should bear the brunt of this.

A fix for this "issue" would be to give all of us 10 bars on the gauge instead of 12 (18KWH usable or less), so the degradation would not show up for an even longer time.

This is not true. I noticed a reduction in range about a month before losing the first capacity bar. A 40 mile commute that I could do in 5-6 fuel bars started taking 6-7, then 7-8, now 8-9. The change from 5-6 to 6-7 actually happened in a very mild March here in Phoenix, and from then it got bad... FAST.

20, 30, or 50%? Even two bars down would give you far more utility than that - if I am overly patronizing, it is likely due to you over dramatizing.

This is not being overly dramatic. If you take my real range of 58 miles to LBW as compared to 80 miles 6 months ago, I have 72.5% of my original capacity after 15 months of ownership. It seems that I am only weeks ahead of at least 30 other cars in warm climates that will experience the same phenomenon. There is no indication yet of this leveling off.

I love that Nissan came out and tried this, and I do applaud them for it. But by not including TMS, they made a fatal flaw that could doom the program with bad press. I have owned Nissans most of my life, except for a brief stint with an Audi and a 2002 Insight and am bummed that they are failing me now. I'm not convinced that a lot of the rest of the country won't be a few months to a year behind us in the Southwest with respect to capacity loss.

I want consumers to be aware of this issue, because I do not think the LEAF should continue to be sold under the current EPA ratings nor the advertised expectations of 80% after 5 years. The forward-looking statement of residual capacity can and should be wholly thrown-out until there are actually an overwhelming majority of cars that have made it that far with that capacity. We know many batteries that will not be at 80% at 5 years (because they've already past that threshold), and we know of 0 that will definately be at 80% at 5 years.

 

[Caracalover]

A fix for this "issue" would be to give all of us 10 bars on the gauge instead of 12 (18KWH usable or less), so the degradation would not show up for an even longer time.

This is not true. I noticed a reduction in range about a month before losing the first capacity bar. A 40 mile commute that I could do in 5-6 fuel bars started taking 6-7, then 7-8, now 8-9. The change from 5-6 to 6-7 actually happened in a very mild March here in Phoenix, and from then it got bad... FAST.

The bars I meant were for capacity, not state of charge. That would mean the 74 miles EPA would be something below 60, and the Nissan claim would have been around 75. We now have around 20KWH usable of a 24KWH battery, a fix would be to only let us have access to 18KWH, allowing for 3KWH safe zones on each end of the battery charging cycles instead of 2. That is what they have done with the Volt I believe, even though it has climate control for its pack.

I have also had state of charge bars do strange things, but for me, it is easy to write it off to software issues. At delivery I could do the trip home from the desert with 4 bars remaining. After the first software "fix" I saw the same trip having 3 bars remaining, and now with the latest software I end with just 2 bars. I don't see the LBW so I don't think my battery is failing, I just think the parameters for measuring it keep changing.

From what you describe it sounds like you do have an issue with the battery, not with the software.

 

[DaveinOlyWA]

azdre; your capacity loss seems to be much higher than most reported here. i have seen several reporting 10-20% but you think you have lost 27.5%? wow that is extreme

 

[TLeaf]

Sounds like it's time for Nissan to start tearing into some of these battery packs to find out what's failing.. I'd think they should be relishing the idea, getting a chance to look at real-world high-temp batteries. Perhaps it's just specific modules that are failing? Perhaps it's even just a few specific cells that are knocking some modules out of commission?? Think of it: we've got 192 cells scattered across 48 modules. If only 10% of those cells went gunny-bag, you could conceivably take out 39% of your battery (19 modules) depending on how the BMS manages and accounts for non-spec modules.

 

[LEAFfan]

Sounds like it's time for Nissan to start tearing into some of these battery packs to find out what's failing.. I'd think they should be relishing the idea, getting a chance to look at real-world high-temp batteries. Perhaps it's just specific modules that are failing? Perhaps it's even just a few specific cells that are knocking some modules out of commission?? Think of it: we've got 192 cells scattered across 48 modules. If only 10% of those cells went gunny-bag, you could conceivably take out 39% of your battery (19 modules) depending on how the BMS manages and accounts for non-spec modules.

Many of us have taken our cars in, and I haven't heard one yet say that they had bad modules or bad cells. I took mine in a month early (May) because I had the EVBS warning light come on three times, once during QCing and the other two after QCing. They checked each module and cell and there were no bad cells or modules and at that time I was around an 8-10% loss. Nissan told my tech that something with the Quick Charger was triggering the light. He reset the code/s and it hasn't reappeared since.
Trust me on this, it's the high ambient heat over time that is degrading our battery packs. I know someone that had their whole battery pack replaced here seven months ago, and they've already lost a capacity bar with their new pack! It's left out in the searing heat every day at work and a hot garage at night.
I received a 'survey' from Nissan today and I recommended they replace all of our Phoenix area packs no matter how much capacity all of us have lost with a 24kW h Toshiba battery pack like that used in the Honda Fit (20kW h) and the iMiEV (16kW h). According to their website, they can withstand up to 122F with very little or no degradation without any active cooling. This would be a great solution until A123 has their new pack ready.

 

[TLeaf]

Trust me on this, it's the high ambient heat over time that is degrading our battery packs.

I agree entirely with this, I'm just trying to come up with some explanation as to why the degradation is occurring so much faster on some cars than anticipated. The closest analogy I have is the group experience with the Vectrix scooters: these scoots have a 102 cell NiCd pack and a "typical" range of 30 miles. Kill even 1 or 2 of these cells through heat and the bike's range can easily drop in half owing to how the bike's BMS interprets the voltage drop. The trick is that short-circuiting these 1 or 2 bad cells can almost completely restore the range since the BMS is no longer registering the speedy fall-off in voltage as these weak cells lose their minimal capacity.

Sure, sure, these are NiCd cells (not Li), 102 cells (not 192 cells), etc., but it seems like we don't really know much about how the Leaf's BMS functions. Perhaps it is just such a quick voltage drop at the module level that the BMS is registering, resulting in the associated gids/capacity bar decrease when in fact the vast majority of the cells have only experienced a nominal decrease in capacity. Depending on the thoroughness of the shop's testing equipment, such cell/module failures might not register as perhaps these cells show up as A-OK (testing for voltage?) if the car is tested at near-full capacity. In my Vectrix experience, faulty cells only come to obvious light when you have a nearly dead battery pack that you then place an appreciable load onto..

 

[Stoaty]

Trust me on this, it's the high ambient heat over time that is degrading our battery packs. I know someone that had their whole battery pack replaced here seven months ago, and they've already lost a capacity bar with their new pack! It's left out in the searing heat every day at work and a hot garage at night.

Why was that persons battery pack replaced?

 

[DaveinOlyWA]

Trust me on this, it's the high ambient heat over time that is degrading our battery packs.

I agree entirely with this, I'm just trying to come up with some explanation as to why the degradation is occurring so much faster on some cars than anticipated. The closest analogy I have is the group experience with the Vectrix scooters: these scoots have a 102 cell NiCd pack and a "typical" range of 30 miles. Kill even 1 or 2 of these cells through heat and the bike's range can easily drop in half owing to how the bike's BMS interprets the voltage drop. The trick is that short-circuiting these 1 or 2 bad cells can almost completely restore the range since the BMS is no longer registering the speedy fall-off in voltage as these weak cells lose their minimal capacity.

Sure, sure, these are NiCd cells (not Li), 102 cells (not 192 cells), etc., but it seems like we don't really know much about how the Leaf's BMS functions. Perhaps it is just such a quick voltage drop at the module level that the BMS is registering, resulting in the associated gids/capacity bar decrease when in fact the vast majority of the cells have only experienced a nominal decrease in capacity. Depending on the thoroughness of the shop's testing equipment, such cell/module failures might not register as perhaps these cells show up as A-OK (testing for voltage?) if the car is tested at near-full capacity. In my Vectrix experience, faulty cells only come to obvious light when you have a nearly dead battery pack that you then place an appreciable load onto..

but most with loss are reporting this within days of having a near perfect battery check which means no bad cells

 

[Herm]

I agree entirely with this, I'm just trying to come up with some explanation as to why the degradation is occurring so much faster on some cars than anticipated.

My guess is that the batteries are seeing much higher temperatures than expected, perhaps parking over a hot pavement, could also be that their Arizona tests were not long enough.

 

[DaveinOlyWA]

I agree entirely with this, I'm just trying to come up with some explanation as to why the degradation is occurring so much faster on some cars than anticipated.

actually our anticipation was based on Nissan's info on a the expected degradation. now, is this something they did not know? unlikely.\

so they had to know this would happen and have to assume they have some sort of contingency plan set up... their response up to now has not been hopeful but i guess soon something is going to happen one way or another

 

[TonyWilliams]

I haven't looked at his data, but as far as I'm concerned, any increase as it got cooler wasn't a "seasonal winter increase" it was a "recovery from a summer decrease".

All I know:
Hot temperatures reduces the ability of the battery to store a charge.
My car did NOT charge to 280 for the first couple months. I am quite sure I remember others reporting this as well.

I'll leave the speculation up to you.

I have observed this with my new 2012 LEAF. With battery at "full" charge when at moderate temps, it would hold 278-280 Gids (I have never actually seen 281, but other drivers did on my car).

When the battery became hot, at over 130F, it would only hold about 255-260 Gid. Once the temp returned to "normal" that same day, it would hold 278-280 Gid again.

 

[DaveinOlyWA]

I haven't looked at his data, but as far as I'm concerned, any increase as it got cooler wasn't a "seasonal winter increase" it was a "recovery from a summer decrease".

All I know:
Hot temperatures reduces the ability of the battery to store a charge.
My car did NOT charge to 280 for the first couple months. I am quite sure I remember others reporting this as well.

I'll leave the speculation up to you.

I have observed this with my new 2012 LEAF. With battery at "full" charge when at moderate temps, it would hold 278-280 Gids (I have never actually seen 281, but other drivers did on my car).

When the battery became hot, at over 130F, it would only hold about 255-260 Gid. Once the temp returned to "normal" that same day, it would hold 278-280 Gid again.

so AZ owners might be jumping the gun a bit... still makes the car non functional. sucks. i go from about 85-87 miles (more or less) in summer to 70-72 miles in winter (very little CC on this. wear a coat!! wont kill ya) but that is the price of rice. i knew that. so in 3-4 years i will start having issues in winter that AZ'rs are experiencing now.

 

[SanDust]

I haven't looked at his data, but as far as I'm concerned, any increase as it got cooler wasn't a "seasonal winter increase" it was a "recovery from a summer decrease".

All I know:
Hot temperatures reduces the ability of the battery to store a charge.
My car did NOT charge to 280 for the first couple months. I am quite sure I remember others reporting this as well.

I'll leave the speculation up to you.

I have observed this with my new 2012 LEAF. With battery at "full" charge when at moderate temps, it would hold 278-280 Gids (I have never actually seen 281, but other drivers did on my car).

When the battery became hot, at over 130F, it would only hold about 255-260 Gid. Once the temp returned to "normal" that same day, it would hold 278-280 Gid again.

Interesting observations. A battery cell can absorb more energy when hot and, once, you've lost battery capacity you can't recover it (for example, once the Li ions have moved from the electrolyte to the anode you can't get them back into play). Based on temperature, the charger may be dialing back the to avoid side reactions and charging more fully when the temperature drops, but you're not "recovering" capacity as cooler temperatures return.

If the capacity bars are linked to charging which is dependent on temperature, then as temperatures cool one or more of the capacity bars may return. However, if the capacity bars truly represent capacity then that won't happen.

 

[DaveEV]

I have observed this with my new 2012 LEAF. With battery at "full" charge when at moderate temps, it would hold 278-280 Gids (I have never actually seen 281, but other drivers did on my car).

When the battery became hot, at over 130F, it would only hold about 255-260 Gid. Once the temp returned to "normal" that same day, it would hold 278-280 Gid again.

Another reason to perform actual range tests to confirm GID readings. Were you able to check 100% charge voltage when the battery was hot? Did it still reach ~394V as expected?

The question is: Is the reduction in GID count when the battery is hot reflects an actual reduction in usable capacity (in theory because the BMS limits max or min voltage) or is simply the result of some sort of temperature correction applied to the GID numbers?