How to measure battery degradation

[Coffee_Slurry]

i was under the impression that the battery checks were free and part of the warranty maintenance program...if not free, how much is it?

I didn't get the impression they were free. Nothing else in the Service Interval schedule is free.
I'd expect to pay anytime I pull into a service bay, unless it was pre-paid as part of the car negotiation.

 

[Herm]

With wheels jacked up? U would get probaly a few thousand "miles" from a charge and I b willing to bet she would run pretty cool even at 90 mph

I'm not sure if you get that many "miles" .. then again we may be surprised. A Leaf owner needs to try it, everyone owns a set of jacktands. At least report the load it generates. Brake and stability sensors may freak out if they dont see the ground rolling by underneath.

 

[JasonT]

i was under the impression that the battery checks were free and part of the warranty maintenance program...if not free, how much is it?

I didn't get the impression they were free.

First and second year checks are free, after that you are expected to pay. Page 8 from the Warranty Information Booklet:

You are required to perform annual EV Battery Usage Report at intervals of 12 months, 24 months, 36 months, 48 months, 60 months, 72 months, and 84 months. These EV Battery Usage Reports can be performed by a Nissan LEAF certified dealer or any qualified repair shop facility. The 12 and 24 month EV Battery Usage Report will be performed at no charge to the customer, provided the work is done at a Nissan LEAF certified dealer.

 

[DaveinOlyWA]

With wheels jacked up? U would get probaly a few thousand "miles" from a charge and I b willing to bet she would run pretty cool even at 90 mph

I'm not sure if you get that many "miles" .. then again we may be surprised. A Leaf owner needs to try it, everyone owns a set of jacktands. At least report the load it generates. Brake and stability sensors may freak out if they dont see the ground rolling by underneath.

no load power on an inefficient electric motor is pretty nominal. if the Leaf's motor is half as efficient as its reported to be, it will run forever on 24 kwh if nothing is holding it back other than bearing friction and wheel weight.

 

[AndyH]

i was under the impression that the battery checks were free and part of the warranty maintenance program...if not free, how much is it?

The service brochure shows required battery health checks at 12 and 24 months. We should be able to request any other reports we wish. It'll take about 5 minutes and will take a Leaf tech and the dealer's Consult diagnostics computer. Maybe a similar price to having a check-engine light reset?

1 Review of the EV Battery Usage Report is required as a condition of EV battery warranty. Refer to your 2011 LEAF warranty information booklet for details. Both the 12 month and 24 month inspections will be performed by your Nissan LEAF certified dealer at no cost to the vehicle owner.

(Service and Maintenance Guide page 16)
http://www.leafic.com/wiki/images/f/ff/2011-Nissan-Leaf-SMG.pdf

 

[garygid]

I asked the dealer about getting the battery check done when I first get the car, and then again every three months, because I wanted to see the test results from a "healthy" battery's early life.

 

[ERG4ALL]

I purchased an iPhone recently my old phone was OLD and I thought it would be nice to have the carwings feature. When reading the manual for the phone it talked about the Li-ion battery. What was news to me was that if you filled the battery and then discharged to 50% capacity, filled it again and then discharged it to 50% capacity that the two fills would only count as one fill when looking at the battery life. If that is the case then we could be charging every night without worrying about the charge cycles per life of the battery.

As was posted earlier, with a life expectancy of 2,500 charge cycles when charging to Nissan 100%, then discharging to 50% after a 100% charge and recharging would allow you to do that somewhere around 5,000 times. The question then becomes how much like the iPhone Li-ion battery is the LEAF battery? Any thoughts?

 

[DaveinOlyWA]

I purchased an iPhone recently my old phone was OLD and I thought it would be nice to have the carwings feature. When reading the manual for the phone it talked about the Li-ion battery. What was news to me was that if you filled the battery and then discharged to 50% capacity, filled it again and then discharged it to 50% capacity that the two fills would only count as one fill when looking at the battery life. If that is the case then we could be charging every night without worrying about the charge cycles per life of the battery.

As was posted earlier, with a life expectancy of 2,500 charge cycles when charging to Nissan 100%, then discharging to 50% after a 100% charge and recharging would allow you to do that somewhere around 5,000 times. The question then becomes how much like the iPhone Li-ion battery is the LEAF battery? Any thoughts?

they are pretty much the same. the big issue is not overcharging the battery. that is why Nissan recommends 80% charging simply because it eliminates the possibility of overcharging. every time you charge to 100% you run the risk of overcharging by just a teeny weeny bit. but even overcharging it by .1 % is enough to cause permanent battery capacity loss. granted, its not much, but do that 50 times and now its 5% and so on

 

[ERG4ALL]

You mean the big issue IS overcharging the battery?

 

[Electric4Me]

With wheels jacked up? U would get probaly a few thousand "miles" from a charge and I b willing to bet she would run pretty cool even at 90 mph

I'm not sure if you get that many "miles" .. then again we may be surprised. A Leaf owner needs to try it, everyone owns a set of jacktands. At least report the load it generates. Brake and stability sensors may freak out if they dont see the ground rolling by underneath.

It would be interesting to see how the Leaf reacts to this. No doubt the traction control would have to be turned off. I know that my Subaru ABS sensor light comes on when I do this (4 wheels off ground).

 

[DaveinOlyWA]

This happened so long ago it probably does not matter but I know a guy who jacked up cars and let them idle in reverse to reset the odometers. There were times he run them all night and they wouldn't hardly burn any gas . I wish I had paid attention to what the estimated gas mileage was but back mpgs were something no one paid attention to

 

[AndyH]

I purchased an iPhone recently my old phone was OLD and I thought it would be nice to have the carwings feature. When reading the manual for the phone it talked about the Li-ion battery. What was news to me was that if you filled the battery and then discharged to 50% capacity, filled it again and then discharged it to 50% capacity that the two fills would only count as one fill when looking at the battery life. If that is the case then we could be charging every night without worrying about the charge cycles per life of the battery.

As was posted earlier, with a life expectancy of 2,500 charge cycles when charging to Nissan 100%, then discharging to 50% after a 100% charge and recharging would allow you to do that somewhere around 5,000 times. The question then becomes how much like the iPhone Li-ion battery is the LEAF battery? Any thoughts?

Absolutely - "One Cycle" is from a full charge to empty and back to full.

If we only drive 10 miles a day (assuming 100 miles LA4 range), and recharge every night to 100%, then we get a complete cycle's worth in 10 days.

 

[AndyH]

they are pretty much the same. the big issue is not overcharging the battery. that is why Nissan recommends 80% charging simply because it eliminates the possibility of overcharging. every time you charge to 100% you run the risk of overcharging by just a teeny weeny bit. but even overcharging it by .1 % is enough to cause permanent battery capacity loss. granted, its not much, but do that 50 times and now its 5% and so on

Overcharge will shorten a lithium cell's life while over-discharging will kill them quickly. That being said, however, I have to disagree with the Leaf's 80%.

The car's management system monitors voltage on every cell group (there are two in parallel). According to the service manual, if the car's computers sense that any cell charges or discharges outside the consumer allowed range, it generates a hard stop - no charge, no drive - flatbed time. The car will not let us get outside the CONSUMER zone.

And the consumer zone is well inside the cell voltage range where damage will occur. It appears that the only way a cell will be allowed to fall outside the range is if we have a computer failure.

It's looking like the "consumer" 100% is 95% of cell capacity while 0% "consumer" is in the 15% total area. If this is true, then there can be some battery life benefit to charging to 90% consumer.

 

[Herm]

they are pretty much the same. the big issue is not overcharging the battery. that is why Nissan recommends 80% charging simply because it eliminates the possibility of overcharging.

No doubt there is some thruth to what you are saying, but it simply ages the battery faster the higher the state of charge is.. lithium-ion batteries are shipped and stored at 50% charge.. they are tested for stability right after menufacturing by charging to 100% and letting the cell rest for about a week to see if it retains the charge. This is called "Forming", a stress test.. probably expensive to do.

Many people suspect the pack is bigger than 24kwh, it has a built-in reserve that you never use. Apparently by opting to charge to 80% you end up only using 65% of the cells raw capacity, note 65% is the hardwired limit GM uses in the Volt's battery. Nissan simply gives you the ability to charge-up to a so-called "100%", try no to do it every day.

 

[DaveinOlyWA]

well the disputable battery management king has to be the Prius. granted, different battery chemistry, much less stress on the batteries, but its all about charge cycle. they have what equates to a cell phone battery lasting 10 years (expected lifespan is 300-500 cycles or 1-2 years...)

they run their SOC from 40 to 80% so no deep discharge, no possibility of overcharge. granted, the Leaf cannot do this and the battery chemistry they do use does allow a deeper discharge without increased degradation. standards "were" no lower than 20% but Nissan has tweaked the chemistry a bit, so hoping they know what they are doing.

the other thing is need. i dont really need 100 miles which allows me to not fully charge. its funny i am talking about this because my Droid was texted at 4:13 am to advise the Leaf is fully charged. that is first time in nearly 2 weeks. now i have charged to what i expect to be in the mid 90's probably 3-5 times in that time because their were days i expected to need most of the range. and actually made turtle mode last Saturday.

so in 5 years with 20% loss, its 80 miles or about 60 miles of "reliable" range. that will only require me to charge more to 100%. but if i maintain my charging to 90-95 % will that mean i might only be at 90 miles or 67 miles of reliable?

 

[garygid]

Apparetly the "charge to 80%" feature (significantly?) affects battery lifetime, at least Nissan calls it a "long life mode". Then, what mode is charging to 100%, a "reduced lifetime" mode? Or, perhaps they would prefer to call it the "average lifetime" mode?

I believe that Nissan has not FULLY disclosed why they have the "80%" feature.

However, since it has been shown that Regen is inoperative at 100% SOC, and is fully functional at 80% (or a bit higher), it is quite possible that "Fully Operable Regen" is one of the unspoken reasons for the 80% feature.

Edited: To make more nearly correct.

 

[DaveinOlyWA]

However, since it has been shown that Regen is inoperative at 100% SOC, and is fully functional at 80% (or a bit higher), it is quite possible that "Fully Operable Regen" is the reason for the 80% feature.

that is the reason (and only reason) why i dont do 100% on a regular basis...just too cheap to think about all that regen i am not getting!

 

[Herm]

I believe Nissan has not said why they have the "80%" feature.

Good point on the regen, but Nissan has said it is to increase battery life.. in the manual.

 

[garygid]

OK, sorry, I did not know of Nissan's explicit statement.
The owner's User Manual?
Do you have a page number, please?
Thanks, Gary

 

[ttweed]

OK, sorry, I did not know of Nissan's explicit statement.
The owner's User Manual?
Do you have a page number, please?

Gary,

It's in the Charging section, p. CH-18, referring to "Long life mode." It is repeated on p. CH-20.

TT