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BlackBerry Curve battery: Cells made in Japan, but assembled where?  (Source: Paul Mah)
Lithium-ion batteries are both a blessing and a curse when it comes to mobile electronics

The topic of exploding lithium-ion batteries has been debated to death in the wake of massive battery recalls over the last couple of years. Amidst the deft public relations maneuvering and finger-pointing, however, the question as to why they explode in the first place is still shrouded in mystery for many.

The most important thing to understand here is that lithium-ion technology is considerably more volatile compared to other forms of rechargeable battery technologies. Defects in the insulating membrane can result in a mini-explosion that rips a battery open to release steam in excess of 600 degrees Fahrenheit.

Manufacturers are aware that it is statistically probable for a lithium-ion to fail, though the calculations employed to sideline the risk are sometimes quite suspect. To determine the mean time between failures (MTBF), manufacturers take a sample of say, 1,000 batteries, which are then used until one fails.

Assuming that the battery that died did so after 100 hours, the MTBF for that batch is pegged at 100,000 hours, or 100 multiplied by 1,000. While satisfying to the QC manager, it is completely meaningless to the consumer. A MTBF of 100,000 hours implies that the battery will work for more than 10 years. This is false; because lithium-ion cells starts deteriorating the moment they are manufactured. On the shelf in a fairly hot warehouse, a fully charged lithium-ion battery could irreversibly lose up to a third of its maximum capacity in just one year.

This does not tell the full story however; until one realizes that lithium-ion itself is a constantly evolving technology.

The exact chemical composition in a modern lithium-ion cell will be quite different from the first commercial lithium-ion that Sony sold in 1991. This is because manufacturers are constantly working to squeeze the best performance by making variations in the battery chemistry.

In the on-going consumer electronics craze that saw an explosion of ever slimmer, high-drain gadgets, the envelope for performance is constantly pushed outwards. Insulating walls are made thinner for smaller batteries and new mixes of chemicals and surface coatings are put in to eke out that extra iota of battery life.

Problems can arise when -- as with manufactured products from time-to-time -- and enhancements don’t work the same way in the real world as they did in the lab. Also, problems might not even show up in the first generation, or until they are placed in high-drain gadgets that didn’t exist before, for example.

Another facade of the situation has to do with the fact that a rechargeable battery pack is actually made up of multiple battery cells. This is where you have manufacturers advertising “8-cell” or “4-cell” laptop batteries. What it also means is that raw lithium-ion cells are increasingly being shipped to another location for assembly into the final battery pack.

Because not all manufacturers are interested in making everything, many choose to buy lithium-ion cells from third parties to assemble into battery packs. Depending on cost efficiencies, it is possible to have battery cells that are made in Japan, but assembled in China or other lower-cost countries.

There are skeptics who believe that quality control – which is of paramount importance in this context, is less than desirable in China. This is exacerbated by the fact that a completed battery can no longer be inspected from the outside or easily tested.  The argument is that workers can take shortcuts and substitute, say, an original insulator with cardboard. Another possibility, as companies such as Mattel experienced first-hand, is that counterfeit raw materials could creep into the bill of materials – with disastrous results.

Where it is arguable that there is little you can do as a single consumer, at least you can figure out where your battery pack is actually put together.

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Is this news, or an editorial?
By ImSpartacus on 5/27/2008 7:17:31 PM , Rating: 5
What exactly is this "story" reporting? It seems to fit into the "blog" category a little better.

RE: Is this news, or an editorial?
By dragonbif on 5/27/2008 8:16:11 PM , Rating: 2
The news is DO NOT TRUST THE MADE IN label on the battery but look at the ASSEMBLED IN. China did a bang up job with Barbie dolls so I 100% trust their skill at putting a battery together that can burn 600F. But we have to keep costs down so make sure you put a good insulator between you and your laptop.
This is news but not braking news that’s for sure. It tells you the problem then gives you some facts; the last part is a bit iffy but o well.

RE: Is this news, or an editorial?
By ImSpartacus on 5/27/2008 8:43:52 PM , Rating: 2
You could say the same about most of the other blogs on this site. They are projecting some sort of "news" in a fashion, but they may draw their own conclusions to boot.

RE: Is this news, or an editorial?
By phxfreddy on 5/27/2008 11:15:55 PM , Rating: 2
You guys actually use your lappy's on battery power? I do not as they do not last so long and I need a place to sit to work. Thus I and most likely the vast majority have 2 steps

-1- sit down

-2- plug in

RE: Is this news, or an editorial?
By Flunk on 5/28/2008 12:40:01 AM , Rating: 2
I use the battery quite a bit, some places just don't have power plugs. I have a fairly cheap HP notebook and it runs about 2.5 hours on one charge which is more than enough for a lot of things.

RE: Is this news, or an editorial?
By freaqie on 5/28/2008 3:15:05 AM , Rating: 1
ofcourse they give good batterylife but if they have a pretty good chance of exploding...

if you think an exploding battery in a laptop is bad...
how about your mobile phone... when it is in you pocket...
that would suck..

although having the laptop on my lap while it goes off would be unpleasant, i think the real danger is with electronics we carry in our pockets..
600 degrees is flesh searing heat... would do massive damage to tissue nomatter how short the exposiure, and then chemicals straight into the wound.....

anyway i like lithium ion/polymer a lot, very good battery's but there should indeed be more quality control

RE: Is this news, or an editorial?
By cogito on 5/29/2008 1:55:27 AM , Rating: 1
Why do you have a laptop, if you're not using it as a mobile computer? A desktop is cheaper and easier to maintain. If you always have your laptop plugged in, you might as well have a desktop.

MTBF, wait what?
By Zurtex on 5/27/2008 9:34:20 PM , Rating: 5
That can't honestly be a used formulae for MTBF?

If the first battery died after 100 hours there's a very good chance mean time before failure is a lot smaller than 11.4 years! Battery failure is very unlikely to be an independent event, that's more than scandalous if they get away with that.

Even if it was an independent event that's still statistically wrong.

RE: MTBF, wait what?
By Martimus on 5/27/2008 10:26:03 PM , Rating: 2
Yeah, that is not a way at all to determine a failure rate. They could wait until all of the bateries have failed and take the average failure time as the MTBF. Of course the conditions used in the test would mean a lot as well. More likely, they just calculate the value.

RE: MTBF, wait what?
By freaqie on 5/28/2008 3:16:32 AM , Rating: 2
its the same with harddrives. and almost everything getting an mtbf rating....
it is pretty nasty indeed

RE: MTBF, wait what?
By Zurtex on 5/28/2008 6:02:34 PM , Rating: 2
Well you obviously wouldn't have time to wait till all died to work out MTBF because of technological pace and economic factors. But you could use just a few dying and some good educated understanding of the battery and the manufacturing process to work out a much better guess than that stupid formulae.

RE: MTBF, wait what?
By Martimus on 5/28/2008 8:54:15 PM , Rating: 2
Yeah, that formula was completely illogical. We used to run a ten year test on all of our components when I used to work for the Auto Industry. It would often take a few months, but we had enough data to know what kind of conditions those components would have throughout it's life and simulated it. They could do the same here by testing it under heavy load and high temperatures and calculate what the actual life would be under normal conditions.

MTBF defined
By 16nm on 5/27/2008 7:29:05 PM , Rating: 2

Those definitions do not look the same to me. It's seems silly to me that anyone could ever believe that a hard drive might endure 1,400,000 hours (160 years) of use.

RE: MTBF defined
By rgsaunders on 5/27/2008 9:40:43 PM , Rating: 3
What they don't tell you about the equation is the part that says "if you replace the product at the manufacturer's recommended replacement interval. ie 3 years, then it will be xxx,xxx,xxx hours before you have a failure."
This part of the formula was leaked by a Western Digital engineer several years ago, but good luck finding reference to it now. I worked several years in quality control and quality assurance, and was a quality systems auditor before I recently retired.

oh no!
By cmontyburns on 5/27/2008 7:14:01 PM , Rating: 2
... "To determine the mean time between failures (MTBF)..."

MTBF should stand for something else. it itchingly begs for another acrostic. i certainly dont look forward to being splashed with particulate matter in excess of 600*F. while reading a DT article.


RE: oh no!
By josh65 on 5/27/2008 11:16:03 PM , Rating: 2
Honestly, i have my laptop sitting on my lap(who would have thought?), and yea, thats exactly what i was thinking the entire time, what happened if it just blew up now? I WANT to have kids when im older.

Statistically probable
By tomthehand on 5/28/2008 8:18:03 AM , Rating: 3
"Manufacturers are aware that it is statistically probable for a lithium-ion to fail"

You're misquoting your source, which says that it is "statistically probable that a small percentage of their cells are going to blow". What you've said is that if you buy a Li-ion battery, it will probably explode.

What your source says is that a small percentage of Li-ion batteries will probably explode. Their use of "statistically probable" combined with "small percentage" is alarmist but technically true; it makes a better story than "there is a small chance that a Li-ion battery could explode". What you've written is both silly and false, and you've linked to a source to give it false credibility. Good work.

Fully charged in warehouse?
By PrinceGaz on 5/28/2008 3:48:09 PM , Rating: 3
On the shelf in a fairly hot warehouse, a fully charged lithium-ion battery could irreversibly lose up to a third of its maximum capacity in just one year.

Which is why Li-Ion batteries never come fully charged, because they lose much less capacity even at high temperatures when less than half charged. At least everything I've bought with a Li-Ion battery has needed to be fully charged before first use.

By nugundam93 on 5/28/2008 10:29:20 AM , Rating: 2
not to be the grammar police and all but...

"eek"? isn't that supposed to be "eke"? :)

yes, work is rather slow today.

Military use of Lion
By stephenfs on 5/28/2008 11:03:14 AM , Rating: 2
I believe that the military still mostly used NMH batteries on their UAVs and other similar devices. They would like to switch to L-ion for obvious reasons, and are looking at ways to monitor each cell to prevent an expensive UAV from going down due to the battery going up in smoke.

"We can't expect users to use common sense. That would eliminate the need for all sorts of legislation, committees, oversight and lawyers." -- Christopher Jennings
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