Capacity Loss on 2011-2012 LEAFs

[Weatherman]

For those of us living in warm climates, all we can really do is whatever necessary to keep the battery temperature down...

Park the car in a shaded location during the day

If you have no choice but to park out in the sun, use a heatshield for the windshield to keep the car's cabin temperatures down.

Park the car outside at night (especially if your enclosed garage tends to stay hot)

Only charge the battery during the early morning hours when temperatures are coolest, and only keep the battery at a high state-of-charge for a minimum amount of time.

 

[Cheezmo]

While borrowing the GID meter, I have charged to 100% 3 times.

265
271
273

80% once...

227

Since I normally charge to 80%, I would guess that is showing the effects of rebalancing over a few 100% charges.

 

[EdmondLeaf]

After all I am not disappointed, and my prediction of 275 was quite accurate. You doing great, let see what you will have by end of summer. Hopefully it will be not as hot as last year.

 

[Ingineer]

It's simple, if you are trying to do a capacity test, whether via reading full Gids or by attempting a range test, you must have a full charge.

Since "full" is highly variable depending on temperature and how balanced your pack is, it's NOT ACCURATE to do one "full" charge on a pack that routinely gets 80% charges and use that as a benchmark! (especially if attempted on a hot pack!)

I usually charge to 80%, but on occasion, I need more range, so I'll bump it to "full" right before my trip. Rarely does this give me close to 280 Gids!

Now if I drive it, then do another full charge or 2, I start seeing the "full" be around my normal 280. I'm in the mild San Francisco Bay Area, so I never really have to worry about temperature, but if you were in Phoenix and your pack is hot during the full charge, it's going to stop prematurely! (Cell Dv/Dt)

If you are trying to assess capacity in this way, then you absolutely need to allow a complete balance cycle (or 2) and it needs to be done in cooler ambient.

Hopefully when I get LEAFSCAN into everyone's hands we can put these capacity worries to rest, as everyone will have easy access to the real capacity figures from the battery ECU, as well as actual pack temperatures.

-Phil

 

[EdmondLeaf]

I'm in the mild San Francisco Bay Area, so I never really have to worry about temperature, but if you were in Phoenix and your pack is hot during the full charge, it's going to stop prematurely! (Cell Dv/Dt)

Does it mean that only people in Phoenix are should be concerned about temp. What in your opinion is the max and min temp that will assure that battery will be in great shape after few(hopefully many) years. Average high in your area is 70F and average low 46F?

 

[Ingineer]

I'm in the mild San Francisco Bay Area, so I never really have to worry about temperature, but if you were in Phoenix and your pack is hot during the full charge, it's going to stop prematurely! (Cell Dv/Dt)

Does it mean that only people in Phoenix are should be concerned about temp. What in your opinion is the max and min temp that will assure that battery will be in great shape after few(hopefully many) years. Average high in your area is 70F and average low 46F?

I honestly don't know, but with Lithium Ion, the general rule is always cooler = less degradation. Only time will tell long-term with the Leaf's pack. I'm anxious to get REAL Instrumentation out to everyone so we can begin learning in earnest with accurate data instead of all this half-guessing.

Obviously, Everyone should move to the Bay Area. :lol:

-Phil

 

[davewill]

... Obviously, Everyone should move to the Bay Area. :lol:

-Phil

I thought that was already tried back in the 90s.

 

[surfingslovak]

... Obviously, Everyone should move to the Bay Area. :lol:

-Phil

I thought that was already tried back in the 90s.

.

 

[tbleakne]

Yes, in terms of driving patterns, I've been harder on my pack than many. While I've never driven the car below VLBW (though I've hit VLBW after pulling into the driveway), I've been below LBW on many occasions.

I am surprised that temperature appears to be such a dominant factor in battery life. Tom, if I were in your shoes, I might consider parking outside at night, or whenever your garage is warmer than the outside temperature. Then again, considering your capacity loss was in the 3-4% range for Year 1, that might not be worth the trouble.

Andrew, thanks for your reply and suggestion. I have been trying active "garage management" for several weeks, ever since I woke up to the loss I have reported. In the current climate (highs in the mid 80s F, lows just below 60 F), I been tracking the garage temperature vs outside ambient. After over-night cooling using a fan, the garage with its insulated main door is cooler than ambient until 3 or 4 PM, at which point I move the car to a shaded parking spot outside. At about 6 pm the ambient temperature drops far enough below the garage temperature, now about 85, for me to re-start the garage fan but leave the car outside. By 10 pm the garage temperature is in the 70s, the outside temperature is lower, and I move the car back inside for the night. If I have not driven much for the day, as was the case the last two days, the battery pack temperature remains at 5 bars. If I have driven more than 10 to 15 miles, the pack temperature goes up to 6 bars, but returns to 5 bars by next morning. All this is slightly extreme, but I am trying to see if it helps. All these temperatures are going to shift up 5 to 10 degrees shortly, with lowest over-night temperatures in the high 70s.

So far all this has not helped, except possibly for a single gid of recovery at 80%, which could be just random. It is too soon to see if these measures slow the decline, or if the decline flattens out anyway as many folks predict. I am not optimistic about the latter.

 

[LEAFfan]

LBW is at the 8.5% SOC point?

No, LBW is at 17.4% on the BCM or Gid meter. VLBW is at 8.5%. Turtle varies between 1.4% and 2.4% depending on speed.

I'll go on my usual tirade again saying that Gids cannot be used to accurately calculate SoC. So far nobody anywhere (except maybe Nissan Engineers or those with beta LEAFSCAN units) can really read SoC. People should avoid the use of gid-based SoC, as once the true SoC is available, this real number is not going to match what Gidmeters report.
-Phil

I guess you didn't notice that I didn't call it SoC, Herm did, yet you put my quote in as if I had said it. You should have noticed my 'BCM'. That stands for Battery Capacity Meter which is exactly what I have. It doesn't measure SoC which I have already pointed out in previous threads, but it does measure battery capacity very well. For example, one driver I scanned was 13-14% down (from 95%) and I told him he would lose a capacity bar soon, and he lost it the next day. True SoC is virtually useless once someone has lost capacity. You could be down to 70% battery capacity left, yet CWs will still show 100% SoC and 12 bars.

 

[LEAFfan]

Obviously, Everyone should move to the Bay Area. :lol:
-Phil

No thanks, I'll take the dry heat over major earthquakes any day.

 

[GRA]

Obviously, Everyone should move to the Bay Area. :lol:
-Phil

No thanks, I'll take the dry heat over major earthquakes any day.

It gives us something to talk about. Whenever one occurs everyone starts guesstimating its magnitude on the Richter scale - '4.7? I'd call it 5.3.' Even Loma Prieta fell into the unusual and maybe inconvenient category (at least, if you're a native), if you weren't in the Cypress structure, the Marina, or a similar area with heavy damage. I'll take the occasional quake over a hurricane or tornado any day, but I imagine it's just a question of what you're used to.

 

[abasile]

I have been trying active "garage management" for several weeks ...

I would imagine that most LEAF owners in particularly hot areas have central air conditioning. One option would be to insulate the garage as well as possible (note tbleakne's insulated garage door), then add an A/C duct to the garage. The LEAF will be happiest if you keep it at or below temperatures that are most comfortable for humans. As some folks have transformed their garages into "hangouts", they might already have A/C.

Alternatively, those in hot areas considering the purchase of an EV should in my opinion consider a model with liquid battery cooling such as a Ford Focus Electric, a Tesla, or a Chevy Volt. Or just lease (not buy) a LEAF. However, given my circumstances, I am glad that I purchased a LEAF.

 

[EdmondLeaf]

I would imagine that most LEAF owners in particularly hot areas have central air conditioning. One option would be to insulate the garage as well as possible (note tbleakne's insulated garage door), then add an A/C duct to the garage. The LEAF will be happiest if you keep it at or below temperatures that are most comfortable for humans. As some folks have transformed their garages into "hangouts", they might already have A/C.

All that is great but Leaf should reduce pollution and save me money. If I will AC my garage than I am adding cost as well I am not very efficient in using resources that we have. Another problem car will mostly heat up during the day and battery temp will go up while I am at work and car is parked. Not many will find place in the shade and probably none with CC for daytime storage.

 

[Herm]

or just move the Leaf into the house, its not going to drip oil on the carpet. I know someone that parked a Pitts Special fuselage in his living room

 

[EdmondLeaf]

or just move the Leaf into the house, its not going to drip oil on the carpet. I know someone that parked a Pitts Special fuselage in his living room

That will be very good solution, but looks like I have to change the door because current is not wide enough for parking in living room.

 

[DaveEV]

All that is great but Leaf should reduce pollution and save me money. If I will AC my garage than I am adding cost as well I am not very efficient in using resources that we have.

If your water heater is in your garage, you can install a heat-pump water heater which will heat your water and cool your garage. Depending on your situation it may not make much of a difference, though.

Electric ventilation fans can be very efficient - an efficient setup would help vent the garage any time outside temps are cooler than inside (down to a certain temp since in the winter you probably don't want it to get too cold!).

 

[surfingslovak]

or just move the Leaf into the house, its not going to drip oil on the carpet. I know someone that parked a Pitts Special fuselage in his living room

Good one, Herm!

 

[abasile]

All that is great but Leaf should reduce pollution and save me money. If I will AC my garage than I am adding cost as well I am not very efficient in using resources that we have. Another problem car will mostly heat up during the day and battery temp will go up while I am at work and car is parked. Not many will find place in the shade and probably none with CC for daytime storage.

That is of course all true, and is why a car with a liquid-cooled battery pack could be a better choice in hot areas. You only need additional energy to run that cooling loop, not cool an entire garage. On the other hand, if you're in Phoenix and already own a LEAF, it probably makes economic sense to extend its battery life with garage AC or whatever you need to do. Maybe add a couple solar panels to help with the additional AC load.

or just move the Leaf into the house, its not going to drip oil on the carpet. I know someone that parked a Pitts Special fuselage in his living room

Hmmm, maybe some wouldn't mind showing off a Tesla Roadster in their living room. But a LEAF... :lol:

 

[Ingineer]

You should have noticed my 'BCM'. That stands for Battery Capacity Meter which is exactly what I have. It doesn't measure SoC which I have already pointed out in previous threads, but it does measure battery capacity very well. For example, one driver I scanned was 13-14% down (from 95%) and I told him he would lose a capacity bar soon, and he lost it the next day. True SoC is virtually useless once someone has lost capacity. You could be down to 70% battery capacity left, yet CWs will still show 100% SoC and 12 bars.

Sorry, my bad for confusing you with Herm. But to be accurate, you do not have a battery capacity meter, you have a stored energy indicator. Capacity depends on how "full" you can get any given battery, and as should be obvious by now, the stopping point in the Leaf is highly variable and dependent on many factors. YOU are the capacity meter, as you interpret data from your gauge and attempt (with rough data) to derive a capacity. The point is, your meter does not directly show capacity, that is something you must come up with, and it will be far from accurate.

The fact remains, other than what the Leaf already gives us on the dashboard, the only other battery metrics that have been gleaned from the Leaf by anyone publicly, (obviously excluding my work) has been battery volts, amps, and stored watt-hours aka "gids" which is relatively coarse (80 watt-hour increments with notably high hysteresis). Your meter only has access to this data, which makes it essentially the same as Gary's "gidmeter".

I'm not trying to scold or boast, I just want to be clear and separate the hard factual data from the guesstimations. Otherwise people may erroneously believe you have REAL factual data, which, in fact, you do not.. I'm working hard to get the LEAFSCAN tool out so we can finally have real hard data from the battery ECU, and stop the speculative assumptions.


-Phil