Capacity Loss on 2011-2012 LEAFs

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Tajim said:
I am very concerned about this issue. I live in South Florida. After reading these post I have to imagine that it is a matter of time (soon) that I will have the same loss as everybody else.
Click to expand...

Don't overreact, yet. There's a big difference between our temperatures in South Florida and Pheonix. Hopefully these problems will get all hashed out before anyone here in Florida has to deal with it. To be safe, just avoid charging to 100% when not necessary, don't leave the car sit for a long time at 100% charge, and try to minimize the time the car sits over hot black asphalt. The only change I've really made is using a Stop Time only timer for the weekends when I charge to 100%, so the car only sits for an hour or so at 100% before I leave.
 
drees said:
A "cycle" doesn't mean anything here unless you are taking it from 100% to turtle. Partial cycles just don't directly relate. It could take 4 50% cycles to equal the wear of 1 100% cycle. It could take 2 70% cycles to equal 1 100% cycle.
Click to expand...

You are right, a cycle from 100% down to 40% is not the same as a cycle from 80% down to 20%, in terms of battery wear.

The USABC long-term goals for EV batteries call for 1,000 cycles at 80% DOD and 10 years.. Nissan cycles are 92% from full charge down to turtle, or 78% from full charge to VLBW.. or a 63% cycle from an 80% charge to VLBW. The last one matches what the Volt does at all times.

The full charge down to turtle is an abusive cycle.
 
keydiver said:
Tajim said:
I am very concerned about this issue. I live in South Florida. After reading these post I have to imagine that it is a matter of time (soon) that I will have the same loss as everybody else.
Click to expand...

Don't overreact, yet. There's a big difference between our temperatures in South Florida and Phoenix.
Click to expand...

Agreed. Contrary to something I recently read, South Florida does not have a hot, harsh climate. In fact, where I'm at right now it's cloudy, raining and 82 degrees. Pretty typical summer weather.

If you like the LEAF and are willing to do a little "battery temperature management" of your own, I'd suggest the following:

1) Park the car outside at night. If you have an enclosed garage, it can be as much as 10 degrees warmer overnight in the garage than it is outside.
2) Park in the shade during the day, or, at least in a location that gets some shade during the day.
3) Buy and use a HeatShield for your windshield. It's amazing how much cooler the car's cabin is when most of the sunlight is reflected away.
4) Only charge your battery during the early morning hours when it's "cool".
5) If you don't drive a long distance in a typical day, don't even charge to 80%. I drive about 35 miles a day, and I charge to 67% (8 bars). It requires manual intervention, of course. I still have two bars left at the end of the day.
 
TickTock said:
Curious. My new 100% charge did reach a higher gid count by 6% (now 231 vs 217 before) however, I still drew almost exactly the same charge from the wall for a turtle to 100% charge (20.8kWh). I'll check if the logs offer any explanation later today. Still 12 capacity bars.
Click to expand...

well that is more than the 13% degradation Nissan claimed you had. you should only have 11 capacity bars
 
DaveinOlyWA said:
well, i think if they had replaced any modules, they would have mentioned it.
Click to expand...

I think just the opposite. Since they, quite obviously, know this could REALLY blow up for them, Nissan isn't likely to share anything with us. The only way you might see that data is through "discovery" or "deposition", if it doesn't mysteriously get lost.
 
DaveinOlyWA said:
TickTock said:
Curious. My new 100% charge did reach a higher gid count by 6% (now 231 vs 217 before) however, I still drew almost exactly the same charge from the wall for a turtle to 100% charge (20.8kWh). I'll check if the logs offer any explanation later today. Still 12 capacity bars.
Click to expand...

well that is more than the 13% degradation Nissan claimed you had. you should only have 11 capacity bars
Click to expand...
The first time TickTock lost his 12th bar he was at ~228. Turbo2ltr lost his at 231. It should disappear anytime now unless Nissan has changed something.
 
Given the degradation issues I wonder why chargers are not voltage variable. It seems a lot of heat comes from pushing with higher voltage by the L2. Most people would charge overnight and the charge could be spread over a longer time period.
 
shrink said:
Opposum/azdre's car and Scott's car were presumably subject to the same conditions and testing.
Click to expand...
I do not make that presumption. For all we know they may have applied six different "band-aid solutions" to each of the six cars and they are watching to see which one is best received. One of the cars may have been a control to which they did nothing.

I'm wondering, did anyone "watch" their car via CarWings while it was in Casa Grande to see what might be happening with it?
 
Alric said:
Given the degradation issues I wonder why chargers are not voltage variable. It seems a lot of heat comes from pushing with higher voltage by the L2. Most people would charge overnight and the charge could be spread over a longer time period.
Click to expand...
I'm sure the charger in the LEAF is capable of charging at a wide range of currents, it does not need a voltage-variable supply to do this. Nissan can program the charger to operate at whatever rate they choose. But it's always somewhat of a trade off between convenience and battery life.
 
I don't believe this is going to make any appreciable difference since the Leaf's battery pack is sealed and beneath the car, outside of the cabin environment. Thus, cabin temperatures will not have any noticable influence on battery temps.

Weatherman said:
3) Buy and use a HeatShield for your windshield. It's amazing how much cooler the car's cabin is when most of the sunlight is reflected away.
Click to expand...
 
Weatherman said:
keydiver said:
Tajim said:
I am very concerned about this issue. I live in South Florida. After reading these post I have to imagine that it is a matter of time (soon) that I will have the same loss as everybody else.
Click to expand...

Don't overreact, yet. There's a big difference between our temperatures in South Florida and Phoenix.
Click to expand...

Agreed. Contrary to something I recently read, South Florida does not have a hot, harsh climate. In fact, where I'm at right now it's cloudy, raining and 82 degrees. Pretty typical summer weather.

If you like the LEAF and are willing to do a little "battery temperature management" of your own, I'd suggest the following:

1) Park the car outside at night. If you have an enclosed garage, it can be as much as 10 degrees warmer overnight in the garage than it is outside.
2) Park in the shade during the day, or, at least in a location that gets some shade during the day.
3) Buy and use a HeatShield for your windshield. It's amazing how much cooler the car's cabin is when most of the sunlight is reflected away.
4) Only charge your battery during the early morning hours when it's "cool".
5) If you don't drive a long distance in a typical day, don't even charge to 80%. I drive about 35 miles a day, and I charge to 67% (8 bars). It requires manual intervention, of course. I still have two bars left at the end of the day.
Click to expand...

I have followed most of these recommendation to date, except #1, as we park in the garage at night. I usually never go lower than 2 bars above red. I will let everybody know when I loose a bar. By the way, I have never turtled the car.

Thanks for the info.
 
New article on Battery Degredation and what Nissan is(should) be doing about it:

http://www.autoevolution.com/news/arizona-nissan-leaf-battery-problem-thickens-46508.html" onclick="window.open(this.href);return false;
 
drees said:
IMO - just about all the capacity loss we've seen is "normal". I simply think that either Nissan was a bit naive to think that losing 10-25% capacity after one year is acceptable to consumers when they are expecting 20% after 5 years worst case scenario.
Click to expand...

Which is why GM built in capacity to be used as the battery degrades, AND added TMS to mitigate degradation in hot climates.

smkettner said:
Average just does not work.
Click to expand...
drees said:
Month / Phoenix / Miramar / Difference
Jul 2012....94 .........70 ..........24


Wow - using this data it's rare that San Diego has a mean temperature lower than Phoenix - only happens in Dec. But for 6 months of the year the Phoenix mean temp is 20-30F higher than San Diego! I have no idea how weather.com gets it's average temperature, but saying on average 6F warmer is certainly very misleading.
Click to expand...


Thanks for putting this together.
 
Actually, the C charge rate for the size of the battery is quite low at L2 3.3Kw. Very little heat is produced from such charging.

Alric said:
Given the degradation issues I wonder why chargers are not voltage variable. It seems a lot of heat comes from pushing with higher voltage by the L2. Most people would charge overnight and the charge could be spread over a longer time period.
Click to expand...
 
TomT said:
I don't believe this is going to make any appreciable difference since the Leaf's battery pack is sealed and beneath the car, outside of the cabin environment. Thus, cabin temperatures will not have any noticable influence on battery temps.

Weatherman said:
3) Buy and use a HeatShield for your windshield. It's amazing how much cooler the car's cabin is when most of the sunlight is reflected away.
Click to expand...
Click to expand...

I know there have been a number of studies which focus on "solar loading" and its affect on battery life, so I put it in there as a recommendation, just in case.

This one might be pretty easy to test by putting a max/min thermometer in the compartment where the HV disconnect plug is located and put the cover plate back on. If there's little radiant heat from the cabin, the temp in that compartment should stay closer to the outside air temp than the cabin temp.
 
TomT said:
I don't believe this is going to make any appreciable difference since the Leaf's battery pack is sealed and beneath the car, outside of the cabin environment. Thus, cabin temperatures will not have any noticeable influence on battery temps.
Click to expand...

It will make a difference to your AC load.

How about lining the plastic shield under the battery with AC duct aluminum tape?.. this should reflect off some of the pavement radiant heat but not degrade heat carried away by the air too much.
 
TonyWilliams said:
drees said:
IMO - just about all the capacity loss we've seen is "normal". I simply think that either Nissan was a bit naive to think that losing 10-25% capacity after one year is acceptable to consumers when they are expecting 20% after 5 years worst case scenario.
Click to expand...

Which is why GM built in capacity to be used as the battery degrades, AND added TMS to mitigate degradation in hot climates.

smkettner said:
Average just does not work.
Click to expand...
drees said:
Month / Phoenix / Miramar / Difference
Jul 2012....94 .........70 ..........24


Wow - using this data it's rare that San Diego has a mean temperature lower than Phoenix - only happens in Dec. But for 6 months of the year the Phoenix mean temp is 20-30F higher than San Diego! I have no idea how weather.com gets it's average temperature, but saying on average 6F warmer is certainly very misleading.
Click to expand...


Thanks for putting this together.
Click to expand...


I believe GM did that because they were required. The pack is part of the emissions system on a hybrid and must meet specific warranty criteria just like the Prius. Opening capacity is a solution to this requirement. If Nissan had to meet this requirement things would be different but the pack on a full EV is not part of the emission control system.
 
Tajim said:
Hello, as a long time lurker, first time poster, I am very concerned about this issue. I bought my leaf in Feb of this year. It was a 2011 demo with 400 miles on it. I live in South Florida. After reading these post I have to imagine that it is a matter of time (soon) that I will have the same loss as everybody else. I still have full bars at 100% charge, but now only get 9 bars at 80%. Only 5000 miles on the car.
Click to expand...
Unfortunately, since you bought a demo LEAF, as did I, your car very likely sat at 100% charge for six months before you bought it. It's also likely that all of these demo LEAFs had undisclosed battery degradation at the time that we purchased them independent of the number of miles on the odometer. Caveat emptor!
 
Weatherman said:
TomT said:
I don't believe this is going to make any appreciable difference since the Leaf's battery pack is sealed and beneath the car, outside of the cabin environment. Thus, cabin temperatures will not have any noticable influence on battery temps.

Weatherman said:
3) Buy and use a HeatShield for your windshield. It's amazing how much cooler the car's cabin is when most of the sunlight is reflected away.
Click to expand...
Click to expand...

I know there have been a number of studies which focus on "solar loading" and its affect on battery life, so I put it in there as a recommendation, just in case.

This one might be pretty easy to test by putting a max/min thermometer in the compartment where the HV disconnect plug is located and put the cover plate back on. If there's little radiant heat from the cabin, the temp in that compartment should stay closer to the outside air temp than the cabin temp.
Click to expand...
yup:
Leaf Battery Temp over 24 hours

Upper temperature reading is taken from inside the hatch area.
 
Since that compartment is outside the battery environment, I'm not sure how relevant such data would be to actual pack temperature as their is significant thermal isolation between the two... A heat shield will reduce your initial A/C load however, so it is certainly beneficial from that perspective if nothing else...

Weatherman said:
This one might be pretty easy to test by putting a max/min thermometer in the compartment where the HV disconnect plug is located and put the cover plate back on. If there's little radiant heat from the cabin, the temp in that compartment should stay closer to the outside air temp than the cabin temp.
Click to expand...
 

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