Charge Discharge Cycles

How many full charge discharge cycles can you get from the Leaf cells.

Not sure what you mean how many can you do? You can keep doing those full cycles for many years on end, the pertinent question is what will happen to the capacity of a fully charged battery over time, charging cycles, ambient temperature, etc. The best way to answer this for you individual situation is to use the Battery Aging Model spreadsheet, available for download on the Wiki here:

http://www.mynissanleaf.com/wiki/index.php?title=Battery_Capacity_Loss#Battery_Aging_Model" onclick="window.open(this.href);return false;

To 80% of full capacity. Most companies give a reasonable charge discharge count. LiFePO4 cells typically get round 2000 full charge and discharge cycles. Cut that to 80% full/empty and it jumps to 5000. So for the Leaf cells and a FULL Charge and Full Discharge, how many times before you reach around 80% of the original capacity.

My Leaf has 20,000 miles so far and is not really showing much in the way of loss of capacity.


A question has been asked: How good does a battery have to be for EV's to go mainstream? I said as good as we have right now. A few are arguing that that is not so. It is a simple question and simple answer.

I want to know what the Full Charge Discharge Cycle Life is for the Leaf to 80% original capacity. That is all. I am asking the same question about the Tesla Battery Pack.

Nissan has not provided any information regarding cycle life aside from the estimated 80% in 5 years and 70% in 10 years, assuming normal driving patterns and annual mileage. The only publicly available data is on the AESC website. Of course, you can ask this question Nissan directly via the usual communications channels. Please update this thread should you learn anything beyond what's been posted here.

From other examples of the chemistry that Nissan uses (plus some hints from Nissan) probably 1000 full cycles, perhaps 1500 if you are optimistic. Nissan only allows you to cycle the pack from 2% up to 95% at worst so that helps.. but if you charge up to the recommended 80% and discharge down to 17% (when the last fuel bar disappears) then you are only cycling the battery 63% and that will increase the number of cycles tremendously before the battery reaches EOL at 70% remaining capacity... perhaps 3000 of those cycles.

Herm said:

From other examples of the chemistry that Nissan uses (plus some hints from Nissan) probably 1000 full cycles, perhaps 1500 if you are optimistic.

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Herm, is that until 70% remaining capacity? How do we account for calendar degradation? There are anecdotal reports, which seem to indicate that the LEAF can lose anywhere between 4 to 8% capacity just sitting on a dealer lot after the first 12 months, depending on the local climate of course. TaylorSFguy is at about 80% remaining capacity after 70K miles in the cool PNW. That's between 800 to 900 battery cycles, with his average energy economy, when you assume 21 kWh usable capacity.

I asked. No response yet. I figured about 3000 cycles to 80% or more for the life of the pack to 8 years. Not likely that they would really warranty a pack that will end once the warranty is up. If I had an 8 year warranty I'd expect to get better than 8 years usable vehicle miles.

So far I have a tad over 20,000 miles and have not noticed any real capacity loss. The Guess-O-Meter really sucks and varies a great deal even with my consistent drive on a daily basis. Even with cruise on the noted distances vary by quite a bit. I only go by the bars and they are not even consistent. But I do have a cool 20,000 miles and love My Leaf.

Pete

electricvw said:

I asked. No response yet.

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Not surprising.

electricvw said:

I figured about 3000 cycles to 80% or more for the life of the pack to 8 years.

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Based on anecdotal reports from other owners, this seems unlikely even in cool climates like the PNW.

electricvw said:

Not likely that they would really warranty a pack that will end once the warranty is up. If I had an 8 year warranty I'd expect to get better than 8 years usable vehicle miles.

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This all depends on your range expectations. If a reduced range will work for you, chances are that you will get good use of the LEAF.

electricvw said:

So far I have a tad over 20,000 miles and have not noticed any real capacity loss.

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Good for you, Pete! If you don't mind me asking, what's your approximate geographic location?

Don't mind letting you know. I am just North of Sacramento in Yuba City/Marysville area. I am actually in Marysville. We have no close public charging stations. We have now at least 4 Leafs in our general area. Meaning Marysville and Yuba City. I drive hwy 70 to and from work every day and the commute is 45 miles round trip. I drive pretty much at 57 mph. Today I drove home at 63 mph. I get and average (according to the guess-o-meter) about 65 miles in the winter and around 75 in the summer. Was the same last year too. I usually preheat the cabin before leaving and turn on the defrost a few times during the morning commute. I use the air in the summer and if I am doing more local driving I use the heat in the winter for the shorter drives I do. I do hit the heat sometimes in the morning while going to work. Cool but comfortable. I have no problem with a 70 mile range vehicle for 90% of my driving. No need for a 300 mile car. I'd like about 120 mile range at 65 mph but for now 70 is more than plenty. My Wife will get the Leaf when my Ghia is finished. I expect to get about 120 plus miles with that vehicle. She likes the Leaf too. No doubt that electric is the way to go. We also have full solar on our home too. It really is not a feel good thing like some folks like to slam in your face but I say, why not. Feeling good about what I am doing and my part in the change thats coming is great. Really less of an ego thing and more of get off your duff and do the right thing sort of thing. Been doing green before green was a thing.

Pete

surfingslovak said:

Herm, is that until 70% remaining capacity?

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Always measured to that, its an arbitrary industry number.

No idea on calendar aging.. how long would a battery kept at 40% and refrigerated last?.. probably decades if internal corrosion was well controlled.

surfingslovak said:

TaylorSFguy is at about 80% remaining capacity after 70K miles in the cool PNW. That's between 800 to 900 battery cycles, with his average energy economy, when you assume 21 kWh usable capacity.

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Perhaps you should use a base capacity closer to 24kWh, but in any case it will make little difference from your 800-900 calculation. So is he halfway thru the life of the battery or only one third?

Herm said:

Perhaps you should use a base capacity closer to 24kWh, but in any case it will make little difference from your 800-900 calculation. So is he halfway thru the life of the battery or only one third?

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OK, when we use the rated capacity, then it's about 700 cycles to 80% original capacity in Seattle.

I thought we should adjust charging limitations and to reference the usable 21kWh vs the battery capacity of 24kWh? We generally cycle between 16-18kWh per day charging only to 80% on most days, and constantly on and off the EVSE. Id be interested with my charging schedule how well my battery pack will take over the course of a few years.

surfingslovak said:

Herm said:

Perhaps you should use a base capacity closer to 24kWh, but in any case it will make little difference from your 800-900 calculation. So is he halfway thru the life of the battery or only one third?

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OK, when we use the rated capacity, then it's about 700 cycles to 80% original capacity in Seattle.

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I charge to 100% twice a day and am currently plugging in at dashed lines or close to it depending on the day, wind, weather, my mood etc. I am 13 weeks short of 2 years and the twice a day charging goes to once per weekend average so 11 times a week x 91 weeks and I'm at 1,000 full cycles. As for mileage, Surfingslovak is a tad high, I have 66,000 miles today.

TaylorSFGuy said:

I charge to 100% twice a day and am currently plugging in at dashed lines or close to it depending on the day, wind, weather, my mood etc. I am 13 weeks short of 2 years and the twice a day charging goes to once per weekend average so 11 times a week x 91 weeks and I'm at 1,000 full cycles. As for mileage, Surfingslovak is a tad high, I have 66,000 miles today.

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Awesome!!! This winter (winter #1) the timer is set to 80% as we are still unsure if after the 3year lease we will keep the car as we have been falling in love with the VOLT and its larger hatch cargo area. But in your milder climate doing these large charge/discharge cycles. Ill be changing my limiter to 100% today. Wife drives harder and consumes extra energy then I do, and your 66k on the clock with what it sounds like minimal impact. 100% here I come!

electricvw said:

How many full charge discharge cycles can you get from the Leaf cells.

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took me a few min to dig it up, but I am doing my own calculations based on this Nasa document that did testing on LiMn202 batteries (same chemistry as the leaf)
the answer to your question for 100% cycles is a bit over 1600 with 83% of the capacity remaining. (tested at room temperature)
of course the number of cycles to 80% increases when the discharge is less than 100%
This article also goes into low temperature testing which is of interest to me as I am in Canada.

http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38085/1/04-1055.pdf

Nice study from 2004

TaylorSFGuy said:

I charge to 100% twice a day and am currently plugging in at dashed lines or close to it depending on the day, wind, weather, my mood etc. I am 13 weeks short of 2 years and the twice a day charging goes to once per weekend average so 11 times a week x 91 weeks and I'm at 1,000 full cycles. As for mileage, Surfingslovak is a tad high, I have 66,000 miles today.

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Thank you for the data, much appreciated. Perhaps you don't see it that way, but you are doing the rest of the LEAF driving world a huge favor by essentially performing a cycle life test in a climate, which is nearly ideal for battery longevity.

That said, looking at your charging history, the 1,000 cycles you are referring to likely cover about 800 cycles relative to 24 kWh. The full rated capacity of is often used as a standard reference for a full charge, which Herm alluded to earlier. Since Nissan does not allow us to access the full pack capacity, any charge cycle we complete, even if it goes from turtle to 100%, is only a partial cycle by definition.

One more thing, I was wondering what your long-term average energy economy might be. I had it pegged at 3.8 m/kWh.

jclemens said:

This article also goes into low temperature testing which is of interest to me as I am in Canada.

http://trs-new.jpl.nasa.gov/dspace/bitstream/2014/38085/1/04-1055.pdf

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None of the low temperature testing is at a consumption rate used in a car. Therefore, it comes up with 95% at really cold temperatures that you will never get in the LEAF.

There is a ton of great info in there, but the discharge rates are extremely low, as would be normal in a satellite in space.

surfingslovak said:

TaylorSFGuy said:

That said, looking at your charging history, the 1,000 cycles you are referring to likely cover about 800 cycles relative to 24 kWh. The full rated capacity of is often used as a standard reference for a full charge, which Herm alluded to earlier. Since Nissan does not allow us to access the full pack capacity, any charge cycle we complete, even if it goes from turtle to 100%, is only a partial cycle by definition.

One more thing, I was wondering what your long-term average energy economy might be. I had it pegged at 3.8 m/kWh.

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I realized that after I posted that my day to day full cycles is not the scientific definition. My commute is almost all freeway with little time in traffic.

Carwings info is not reliable for miles/kwh but miles/kw used shows 4.9 in 2011, 5.0 in 2012 and 4.8 YTD in 2013 so you can modify that based on your experience with Carwings accuracy.

I don't have a start to date number but I believe it is a bit over 4 m/kwh. I don't use the heat or AC and have the modified climate controls. 10 bars of charge is getting me 54-57 miles currently. I find that however the first bar goes (fast or slow) the rest of the pack follows. The battery pack temp at 5 bars seems to help as well when cold.