Eight Tips to Extend Battery Life of Your Electric Car

[EVDRIVER]

This article does not go into the why. Charging to 100% generates quite a bit of heat. Quick charging causes heat on the top end. High regen is like QC but it is restricted the same way and is not continuous for long periods. To say QC is damaging is not really true, it is under certain conditions.

 

[TomT]

My personal feeling is that any trip that requires more than one QC en-route each way is farther than I care to take the Leaf. Having to stop every hour (at realistic freeway speeds) to charge for 50 percent of that time is just not practical to me and too time consuming, battery life considerations aside... I'll take the ICE for those trips. (This excludes the consideration that, should one of those QCs goes down, I'm screwed.)

I'm going to agree with you, but I plan on using 3 or 4 to go to SD, Palm Springs, etc.

 

[surfingslovak]

But, the numbers appear to be guesses, that might not apply to any particular battery chemistry, construction, configuration, cooling system, charging rates, usage patterns, or storage conditions.

Gary, you make several excellent points. In case you have missed it, please read Tom Moloughney's report on plugincars.com. He has seen only about 2% annualized average range reduction after 50,000 miles of driving in New Jersey, which is not known for its temperate climate. I believe that the cell chemistry BMW used in the field trial was similar to ours and the ratio of usable to rated capacity was also similar. There was no battery temperature management system to speak of and Tom did not try to coddle his battery pack, quite the opposite. It's too early to tell, and it's always good to err on the side of caution, but this report is good news for Leaf owners.

The MINI-E did not have quick charging capabilities, but it had a more powerful onboard charger. Tom charged 1.5 times per day on average and he reportedly always charged to full.

 

[AndyH]

The LiFePO4 batteries used in the CODA and BYD cars can be charged to 100% all the time, it wont reduce the life of those batteries.

100% ultimate or 100% consumer, Herm?

Because ANY lithium cell charged to 100% of total/ultimate capacity will absolutely and significantly reduce the life of the cell! For LiFePO4, consumer 100% is actually 80% of total capacity - and that 80% will normally return a full expected lifespan of 2000 or so cycles.

 

[AndyH]

The LiFePO4 batteries used in the CODA and BYD cars can be charged to 100% all the time, it wont reduce the life of those batteries.

Right, and I should add that according to the MINI-E spec sheet and other sources the field trial utilized cylindrical manganese spinel cells in 18650 format from E-Moli with a ratio of usable to rated capacity similar to the Leaf. The test cars had only couple of fans to blow cabin air over the pack if it got too hot.

This is absolutely due to the cylindrical cell format. We have documents linked on this board that show IR comparisons between cylindrical and the pouch cells Nissan uses - and auto companies are using pouch cells in large part because of the superior surface area to volume. Pouch cells can handle much higher charge/discharge rates to the same temperature as cylindrical cells. Put another way - they can handle normal operations with nearly zero temperature gain - and one of the pouch cells tested by the national lab cooled during high-rate charging!

I think that Tom Moloughney's field trial experience is quite relevant to us, I wouldn't know of any other publicly available source of information that would cover 27 months, 1,200 charging cycles and 65,000 miles for LiMnO2 cells in an automotive application. Yes, this is a sample size of one, and although I reviewed numerous driver blogs and field trial results, I could not find another comparably documented test car. Generally speaking, the results of the field trial were positive, but there were technical problems as well, the MINI-E was not a production car after all.

The info from the Phoenix endurance testing - which has been referenced on this board from the beginning - will be the most relevant to the Leaf - and though a small sample size, it's larger than one. This 'real world capability' data should not be confused with owners manual legalese.

 

[garygid]

What applies to the Mini or other EVs also applies to the LEAF.

However, HOW MUCH each factor effects the LEAF (or MY LEAF,
or YOUR LEAF) is a totally different matter.

However, the GOOD news is that there are SOME configurations
of battery chemistry, use, etc. that are working quite well.
That bodes well for the future of EVs, even if those tests
do not apply perfectly to any other make and model.

Onward in the march toward a good, clean, systainable planet.

 

[highcountryrider]

All good info.

For me, the 80% charge, 2-10 bars, and cooling before charging fits right into my needs,
so it's not inconvenient and doesn't limit my use of the car. Not the case for everyone.

Much to my dismay, in hindsight, I did not order the QC option, so that's not even a choice
for me.

It will be interesting to see if it really makes any difference over time. I can be sort of a
baseline data point.

 

[surfingslovak]

This is absolutely due to the cylindrical cell format.

Yes, thankw for pointing that out. I believe that this was clear, and likely a correct assessment. We have seen very good thermal performance of AESC cells in everyday use and this is highlighted on their website as well.

The info from the Phoenix endurance testing - which has been referenced on this board from the beginning - will be the most relevant to the Leaf - and though a small sample size, it's larger than one. This 'real world capability' data should not be confused with owners manual legalese.

Well, yes, but there is a very simple legal solution to all this: Nissan should provide battery capacity warranty. Just like GM does, and then we can all forget about it. It wouldn't matter if you purchased or leased, you would have the support of the manufacturer on this.

While I'm interested in this technology and I hope that we will make strides in this direction soon, I don't particularly enjoy looking for shreds of information all over the Internet when when there are simple solutions. This venue has very inadequate search capabilities and if we hope to see high adoption rate of this vehicle, we need an adequate FAQ new owners could actually use. Ideally, Nissan would provide that, along with more adequate and knowledgeable customer support, but we can only wish at this point.

That being said, I will try to find the Phoenix endurance test. However, if you referenced that information in this thread, it would be appreciated. You seem to often say that it's all on the forum, but I did not see any evidence of that. Although there is good info, I often found outdated or inaccurate information as well.

The reason why I like Tom's field report is simple: it's real-world data. An endurance run is valuable and certainly better than lab data, but it's also to some extent synthetic, since it relies on accelerated aging. Based on the other data I have seen, it's also clear that individual owners will see different results and that there will be quite a bit of noise. Just like Gary said, each vehicle will be different due to varying usage, storage and climatic patterns.

 

[AndyH]

This is absolutely due to the cylindrical cell format.

Yes, thankw for pointing that out. I believe that this was clear, and likely a correct assessment. We have seen very good thermal performance of AESC cells in everyday use and this is highlighted on their website as well.

The info from the Phoenix endurance testing - which has been referenced on this board from the beginning - will be the most relevant to the Leaf - and though a small sample size, it's larger than one. This 'real world capability' data should not be confused with owners manual legalese.

Well, yes, but there is a very simple legal solution to all this: Nissan should provide battery capacity warranty. Just like GM does, and then we can all forget about it. It wouldn't matter if you purchased or leased, you would have the support of the manufacturer on this.

While I'm interested in his technology and I hope that we will make strides in this direction soon, I don't particularly enjoy looking for shreds of information all over the Internet or the patronizing attitude some forum members seem to relish in. This venue has very inadequate search capabilities and if we hope to see high adoption rate of this vehicle, we need an adequate FAQ new owners could actually use. Ideally, Nissan would provide that, along with more adequate and knowledgeable customer support, but we can only wish at this point.

That being said, I will try to find the Phoenix endurance test. However, if you referenced that information in this thread, it would be appreciated. The reason why I like Tom's field report is simple: it's real-world data. An endurance run is valuable and certainly better than lab data, but it's also to some extent synthetic, since it relies on accelerated aging. Based on the other data I have seen, it's also clear that individual owners will see different results and that there will be quite a bit of noise. Just like Gary said, each vehicle will be different due to usage, storage and climatic patterns.

Slovak, with respect, I'd like to draw a line between what the Mini-E driver has done and a real lab test. Road tests are interesting but not reproducible, while a lab test is meaningful, repeatable, and reproducible. The only way to generate highly valid data is with a standardized test - and (love it or hate it) that's why things like the LA4 test cycle or other dyno tests exist.

Google is our friend here...

LEAFfan gave us the info in post four of this thread:
http://www.mynissanleaf.com/viewtopic.php?p=137887#p137887

Nissan's had Leafs in Phoenix for hot weather testing since at least June 2010:
http://www.mynissanleaf.com/viewtopic.php?p=6295#p6295
And that testing includes on- and off-road work. I think LeafHopper brought us the best engineer-to-engineer report back in May:
http://www.mynissanleaf.com/viewtopic.php?p=2525#p2525

I got a chance to drive the Leaf test vehicle in Phoenix. I spoke to two members of the design team and 3 members of the test team from Arizona. They have been testing the vehicle all over Arizona and their test track is on the west side of Phoenix near Sun City. They said that all of the cooling is conductive with no active cooling. When I asked about temperatures inside the battery, they replied that the temperature only rose 1 or 2 degrees above the ambient temperature. They did admit that the high temperatures reduced the mileage by 10 to 20%. They also said that they were doing tests in Japan's northern island of Hokkaido this last winter. So they have done an excellent job of testing performance under extreme environmental conditions.

When we talk about battery- or cell-level info, we're talking about tech/engineering info. When we talk about warranties and owners manuals, we're in the corporate attorney's and economist's office(s). Two (or three) different worlds. One of those will have the best battery info...

 

[Herm]

The LiFePO4 batteries used in the CODA and BYD cars can be charged to 100% all the time, it wont reduce the life of those batteries.

100% ultimate or 100% consumer, Herm?

Because ANY lithium cell charged to 100% of total/ultimate capacity will absolutely and significantly reduce the life of the cell! For LiFePO4, consumer 100% is actually 80% of total capacity - and that 80% will normally return a full expected lifespan of 2000 or so cycles.

to 3.6V per cell is 100% capacity, I know you can briefly charge them to a higher voltage (up to 4.2V for up to one hour) but it really serves no purpose to us, the voltage drops away quickly once off the charger. Obviously this assumes you are not heating up the battery excessively or charging an unbalanced pack. LiFePO4 can routinely be charged up to 3.6v per cell, 100% capacity, without reducing its life.

 

[Herm]

I suspect the large pouch laminated cells are cheaper to manufacture and package, compared to a gazillion small cylindrical cells, and that is the reason they are used .. also the manganese-spinel chemistry is much safer than the cobalt chemistry used by Tesla and Mini.

Cylindrical cells have more surface area so they are better suited to forced air cooling and less to conductive cooling.

 

[davewill]

Number 7 has bad advice, for two reasons:

1. Using the remote app always does a 100% charge, which you don't want.
2. The car stops responding to Carwings if it is left off over 14 days, so the remote app wouldn't work anyway.

The advice should be what's in the manual:

If vehicle will not be used for long period of time:
a. NISSAN recommends charging with long life mode.
b. Charge once every 3 months.

For details of the long life mode
charging method, see “Charging timer”
later in this section. If the Li-ion battery
becomes discharged, charge it immediately.

By suggesting 60% (which there's no easy way accomplish anyway) you are creating the scenario where the charge might not stay up for the three months you recommended.

 

[LEAFfan]

My personal feeling is that any trip that requires more than one QC en-route each way is farther than I care to take the Leaf. Having to stop every hour (at realistic freeway speeds) to charge for 50 percent of that time is just not practical to me and too time consuming, battery life considerations aside... I'll take the ICE for those trips. (This excludes the consideration that, should one of those QCs goes down, I'm screwed.)

I'm going to agree with you, but I plan on using 3 or 4 to go to SD, Palm Springs, etc.

First of all, we have different mindsets. I would NEVER drive a gasoline car again on any trip. I bought this LEAF to drive emissions free, help keep our environment cleaner, keep money away from BIG OIL, foreign countries, and to stop using up our natural resources including gasoline, CNG, diesel, etc., AND it is my Primary car. Also, I won't be driving your so-called realistic speeds of 65-75 (60 is plenty fast for me) so I will stop for recharging after 1 1/2 hours @ 80 miles or so (I've exceeded the mileage/m/kW h on Tony's chart at every speed so far.) which is perfect for stretching, using the restroom, snacking, etc. It will be an awesome experience! :mrgreen:

 

[AndyH]

The LiFePO4 batteries used in the CODA and BYD cars can be charged to 100% all the time, it wont reduce the life of those batteries.

100% ultimate or 100% consumer, Herm?

Because ANY lithium cell charged to 100% of total/ultimate capacity will absolutely and significantly reduce the life of the cell! For LiFePO4, consumer 100% is actually 80% of total capacity - and that 80% will normally return a full expected lifespan of 2000 or so cycles.

to 3.6V per cell is 100% capacity, I know you can briefly charge them to a higher voltage (up to 4.2V for up to one hour) but it really serves no purpose to us, the voltage drops away quickly once off the charger. Obviously this assumes you are not heating up the battery excessively or charging an unbalanced pack. LiFePO4 can routinely be charged up to 3.6v per cell, 100% capacity, without reducing its life.

Sorry Herm - this is incorrect.

I work with cylindrical LiFePO4 cells - I test them on the bench and build batteries from the cells. A raw LiFePO4 cell can be charged to between 4.0 and 4.2 V depending on chemistry tweaks/doping. Once the cell is fully saturated (completely through the constant voltage phase until current has dropped to about C/10), the cell is 100% fully charged. The cell can also be discharged to 0 volts - sometimes more than once.

But those are not the voltage points one selects for long cycle or calendar life. For that, we can charge to 4.1-4.2 V, and select between 1.8 - 2.1V for a minimum. This will work but cycle life will be shorter - maybe 1000-1500 cycles.

For a 'standard' 2000 cycle life, we limit low voltage to 2.1-2.5 V and only charge to 3.6-3.7 V - thus using the 80% of total ultimate capacity. This is also known as 'consumer' capacity.

All lithium cells are not alike. They may have some similarities but they have more differences - even when the core chemistry is the same (EV VS. hybrid cells, for example). Added to this we have the difference between 'ultimate capacity/voltage' and 'end-user/consumer' state of charge/voltage limits. It will benefit us greatly if we learn to keep all the different bits of info in their own piles.

 

[AndyH]

I suspect the large pouch laminated cells are cheaper to manufacture and package, compared to a gazillion small cylindrical cells, and that is the reason they are used .. also the manganese-spinel chemistry is much safer than the cobalt chemistry used by Tesla and Mini.

Cylindrical cells have more surface area so they are better suited to forced air cooling and less to conductive cooling.

Cylindrical cells have less surface area to volume. They tend to 'heat soak' and need some cool-down time - precisely because there is less surface area to radiate the heat away. AESC's website shows us an example of this, though not directly:

http://www.eco-aesc-lb.com/en/laminatecell.html


Notice that the cylindrical cell is hotter - 50-55° C - at 10C (8A for a 0.8Ah cell) while the laminated cell was cooler - 30-35° C - at 26C (100A for a 3.8Ah cell). 26C from a 33Ah Leaf cell is 858A. And since the Leaf battery has two cells in parallel, that's like a 1716A charge/discharge.

Cylindrical cells are a commodity product - they're made in high volumes in automated equipment. This is the main reason the standard laptop round cells were chosen by Tesla for the Roadster - because of the lower price.

Prismatic/laminated LiCo cells. Our cells use aluminum and copper, not metallic lithium. The process is similar though.
[youtube]http://www.youtube.com/watch?v=HJrNCjVS0gk[/youtube]

Cylindrical - Tesla - evnow:
http://www.mynissanleaf.com/viewtopic.php?p=14254#p14254

 

[highcountryrider]

You guys are awesome! I can't say I'll use this stuff in my everyday LEAFing, but is is
cool stuff to know.

 

[TomT]

Clearly we both have a different idea of what constitutes an awesome experience! :lol:

It will be an awesome experience!

 

[highcountryrider]

<snip>It will be an awesome experience! :mrgreen:

I'll do it in a New York minute when/if I get the chance.

 

[patrick0101]

This article does not go into the why.

You are correct, the story I wrote was over 4000 words, it was edited down to ~1700 words to fit the sites format better. The "why" sections are primarily what got removed. I'll post the extended edition soon.

 

[patrick0101]

Number 7 has bad advice, for two reasons

Good points. I did say follow the manual if I contradict it in any way.