Battery Life LEAF vs Laptops ?

[SkiTundra]

A friend and I were talking today. His company has been tracking battery life in their laptops for several years (approx 28,000 laptops currently in use so pretty good data). No batteries are lasting more than 3 years, less than 50% of those purchased 2 years ago are still useful. Currently they're seeing capacity reduction (based on useful hours):

6 mos - 5%
12 mos - 22%
18 mos - 62%
24 mos - 73%
30 mos - 88%
36 mos - 90%

Not sure what the differences are in these and those used in LEAF and I assume the laptops always charge to 100% and thus not benefiting from 80% charge longevity and laptops may be more problems with heat.

??

 

[gbarry42]

The chemistry (and the charging philosophy, for that matter), are quite different than that used in the LEAF. Laptops and phones are designed to get as much energy into and out of the battery as possible. In cars, you want them to last longer, and not catch fire, either.

Which makes me wonder how those Teslas are doing.

 

[SkiTundra]

The chemistry ... are quite different than that used in the LEAF.

Leaf, Tesla, and Laptops are all LIon. ??

 

[gbarry42]

Lithium Cobalt Oxide is what's used in laptops and cell phones. EV makers like to use Lithium Iron Phosphate, or Lithium Manganese. They have a lower voltage but they're more durable. I believe the last one I mentioned is used in the LEAF. You can find out about this on Wikipedia, or if you really want to get into it, there's an hour-long lecture you can watch at Carnegie Mellon University.

Saying it uses "Lithium ions" is only part of the whole story. It's kind of like describing your breakfast by saying it had sugar in it.

 

[DarkStar]

...Lithium Manganese...

One of my favorites! You could saw that battery in half and have no reaction at all!

 

[Lopton]

Basically what the guys before me said, the chemistry make up in laptop batteries is different, the Leaf is using LiMn2O4 batteries is my understanding (http://www.greencarcongress.com/2008/05/aesc-lithium-io.html)

you can check out a page or two down a nice chart showing the different types of Li-Ion batteries here http://batteryuniversity.com/learn/article/the_high_power_lithium_ion

-Matt

 

[LakeLeaf]

I run my laptop plugged in 80% of the time. Wonder if those in the study did the same and how that effects the battery life - always keeping at 100% charge.

It would be a neat trick if you could do the same with the LEAF.

 

[adric22]

I run a business that refurbishes Apple laptops and one of the things I have to do is test a ton of used batteries. My requirement is that the battery actually be able to power the computer for 2 hours or it gets replaced. Granted, a brand-new battery typically will do twice that much.

Anyway, the interesting thing is that Apple laptops actually keep track of the number of cycles of a battery. Yet, I find that it really doesn't seem to matter. I can get units in with batteries being only 2 years old having 65 cycles and be worthless, where some batteries can be 6 years old and have 600 cycles and still work for 2 hours. Even though they are all Apple systems, I find that when cracking open some of these batteries, Apple uses different suppliers for the 18650 cells inside.

So what it really comes down to is the quality of the battery. What chemistry is used, what is the build quality like.

Obviously PC laptop manufacturers know the lifespan of a typical PC laptop is about 2 years. So they figure as long as the battery lasts that long, that is good enough. Why spend the money to make the battery last 10 years when they know they original customer won't be using it and the whole thing will probably be in the landfill after that time. With Nissan, they know these cars will still be on the streets in 10 years and their reputation depends on these batteries lasting the test of time. That is why the batteries are so expensive.

 

[Herm]

There are two reasons.. the batteries are always hot, above body temperature and they are mostly kept plugged in and charged to 100% all the time.. plus the manufacturers love selling you replacement batteries

High energy density (high capacity) lithium-ion formulas are used to get the longest running time and lightest weight.. two very important factors for laptops. Iron phosphate and manganese spinel chemistries like the ones used in cars would probably not last long in a laptop either, for the same reasons.. they are popular for BEVs because they are very safe in a crash.. not likely to catch fire or explode. Not good publicity if your BEV shows up on the evening news spewing flames.

There are many instances of people burning down their cars by charging their RC lithium batteries in the trunk.. invariably these use lithium cobalt chemistries and are very volatile.. but the light weight is very important in RC airplanes.. lots burned down car pictures can be seen at http://www.rcgroups.com/

I have ruined many iron phosphate cells in my RC planes and nothing dramatic happens, they get hot and the electrolyte oozes out.. and its not particularly toxic either.

 

[ralphmc]

Well every one hit it on the head in one or the other statement;

The problem is...

None of the laptop Batteries have intelligent cell management build into them, or even decent - over heat protection. Overheating the charge element in the batteries is what kills 95% of the batteries.

I have spent many years with Dell equipment and with portable scan guns, our research showed that if we can avoid the overheating while batteries are being charged we can get greater then 5 years, even as much as 10 years out of those - non managed batteries.

Giving the way that the laptops batteries are being charged - is full current to the end and then off, there is no balancing cycle and no current limiting cycle build into the charging process especially at the near "full" charge level. This kills the battery within a very short live.

The LEAF battery is totally managed - and on top of that a quite bit different cell composition. And it has an extremely smart algorithm to the charging process from low SOC to max SOC, this will keep
the batteries alive many years - I suspect more than 10 years.

Plus don't forget the LEAF battery is a modular 48 x 4 concept that is designed for "High" currents and not for low current (> 1 amp) discharge / charge, which also features a balancing process over all cells.

BTW - if you want to keep your investment of the laptop battery for a long time then once you feed power to the laptop disconnect the battery from the laptop - unless you need to top off for the next travel - then use a timer that shuts of the power to the laptop for the designated charge cycle.

My Dell 1501 laptop 9 Cell battery is > 6 years old and still gives me more than 4 hours of workable power.

Regards,

Ralph

 

[Nubo]

Obviously PC laptop manufacturers know the lifespan of a typical PC laptop is about 2 years. So they figure as long as the battery lasts that long, that is good enough. Why spend the money to make the battery last 10 years when they know they original customer won't be using it and the whole thing will probably be in the landfill after that time.

The newer Apple laptops have integrated non user-replaceable batteries. To make that work, the battery has to have a long life (at least compared to other brands). So Apple warranties the battery for at least 5 years. How do they do this? Similar strategy to an EV -- oversize the battery, don't use its full capacity, and use a careful charge/discharge regime on a per-cell basis.

It's not that the new Apple batteries are so much better than the old Apple batteries. They just chose not to murder them.

a.k.a., "Battery Management System".

 

[JohnnySebring]

My 17" Mac Book Pro is 2 years old has 292 battery cycles and now shows 87% health. I hope the Leaf does much better than that.

My electric R/C airplane Lipo batteries have hundreds of cycles and show no issues so far. I am careful to fly for a strict time limit that never uses more than 80% of the capacity. A low battery can loose your plane. :?: :?:

There is a belief in the electric R/C community that breaking in new batteries will extend the life. This involves only discharging no more than 50% for the first several cycles and keep the current draw to the low side. The lipo cells are a close cousin to the Leaf's battery type. Has anyone heard of any break in procedure for Leafs? :?:

 

[AndyH]

Much of this has been covered in the battery section, by the way.

 

[JohnnySebring]

Yep, I read through all of the Batteries topic. It seems that battery break in isn't required as far as is known at this point.

 

[Nubo]

Yep, I read through all of the Batteries topic. It seems that battery break in isn't required as far as is known at this point.

Well, there is something known as a "forming charge", but I assume Nissan take care of this type of preparatory stuff during manufacture.

 

[AndyH]

Right - the forming charge will be done by the factory. As far as break-in, there's very likely nothing we have to do, but I expect to see some capacity increase during the first 25-100 cycles before capacity starts it slow drop to 80%.

That's based on other lithium variants, though, and not from first-hand experience with the Leaf cells.

 

[Herm]

My 17" Mac Book Pro is 2 years old has 292 battery cycles and now shows 87% health. I hope the Leaf does much better than that.

You still got a ways to go before it hits 80% and is officially spent.. if that is what "health" means. Does your Mac use an "integrated non user-replaceable battery" such as Nubo is talking about?