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Alexander Wolfe
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Blogger
Future capacity?
Alexander Wolfe   7/20/2011 10:17:49 AM
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You raised the big battery elephant in the room question at the end, Chuck, about capacity. Will capacities rise to 4.2A-hr or 4.4A-hr? This of course relates directly to product weight. If capacities don't rise, eventually (soon, actually) portable devices relying on these things will hit a design wall, and the heavier devices will end up being performance-impaired.

Douglas Smock
User Rank
Platinum
Safety Concerns
Douglas Smock   7/20/2011 10:24:58 AM
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What are the safety issues with the laminate-style lithium polymer batteries? It seemed that there was a lot of buzz a couple years ago about potential fires or even small explosions with lithium batteries, but I don't hear much about it anymore. Are these issues addressed in the polymer technology, laminate constructions or just in more robust housings? (Or not at all.)

 

 

Ivan Kirkpatrick
User Rank
Platinum
Thermal Management
Ivan Kirkpatrick   7/20/2011 1:52:09 PM
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The problem before was in cotnrolling the batteries themal characteristics.  Sometimes if the battery was being discharged too rapidly the temperature rose and created the issues already noted.  Smae thing can happen when charging the batteries.  I think the solution was in the modification of the chemistry involved.

In terms of energy storage the total energy stored is getting interesting.  And any uncontrolled release of that energy has to be dealt with in a safe manner.  consider a stick of dynamite.  I am not sure exactly how much energy it stores but when it is released suddenly it has dramatic effects.  If that same energy could be controlled and released gradually in the form of electric current it would make a fine storage device but probably not rechargeable.

If one had a Lithium-Ion type battery with the same energy storage potential as a comparable size stick of dynamite it would certainly warrant very careful attention to catastrophic failure modes. 

As I recall from chemistry class, the most energetic chemical reaction is the conversion of H to H2.  That is Monatomic Hydrogen binding with another free Hydrogen into diatomic Hydrogen, H2.  I believe it also liberates an electron.  Probably not possible to make a battery out of it.

Beth Stackpole
User Rank
Blogger
Re: Future capacity?
Beth Stackpole   7/21/2011 3:41:57 PM
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Is there some kind of Moore's law governing capacity in batteries as there is in processor design? Perhaps a technology that's the equivalent of multi-core for batteries? It would seem there would have to be as devices get smaller malland ser and as as people become ever more reliant on them on a 24/7 cycle. I don't see that demand dissipating any time soon.

BobGroh
User Rank
Platinum
Lithium Ion batteries have created huge shift in model airplane field
BobGroh   7/26/2011 10:34:29 PM
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The increased energy capacity combined with the lighter weight and the high discharge rates of Lithium Ion batteries has completely transformed certain areas of model airplane flying.  Using battery power instead of gasoline or other liquid fuels has been played with for a long time but the emergency of the Lithium Ion in a soft, flexible (and lower weight) has completely transformed the hobby. Many fliers of Radio Controlled (R/C) planes have completely switched over to electric power (I know that I have) for planes ranging from very, very small (sub-ounce weights) to very large aircraft.

Electric propulsion systems have also expanded into control line planes (U/C - planes which fly with lines attached) and free flight (just fire them up and launch them into the air!).  Absolutely amazing and quite liberating - no starters, no fuel cans, pumps, batteries for glow plugs, etc.  Wonderful.

Of course there has been a bit of learning curve for the hobby. We needed new safety procedures (there is a lot of energy in a charged battery and they have been known to break into flame), new ways (using electronic speed controllers) to control motor speed, new brushless motors for high speed and high output applications,  special battery chargers (seems like every battery chemistry has it's own special requirements for charging and maintenance) and the like.

A great revolution which is still going on.

kenw1213
User Rank
Iron
Safe flat lithium polymer battery
kenw1213   7/28/2011 9:35:29 AM
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Forgot the company, but one company boasted their construction method for the flat polymer battery that made it safer when punctured (and layers shorted) with metal spike!  Who is that company?

Hellmut Kohlsdorf
User Rank
Gold
Re: Thermal Management
Hellmut Kohlsdorf   7/28/2011 12:49:05 PM
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Hi Ivan

Fuel cells are the devices that transform hidrogen in electrical energy and water! I see a lot taking place here in germany to have very small devices of this kind

Ratsky
User Rank
Platinum
Re: Safe flat lithium polymer battery
Ratsky   7/28/2011 2:15:39 PM
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That wasn't a lithium-polymer battery!  It was an SLA (sealed lead-acid) one, and it was made by Gates (as I recall) quite a few years ago.  They were the first to use a "super-gelled" electrolyte to make an extremely leak-proof cell structure.  I saw a demo (of a nail being driven through one of their batteries which continued to deliver full power to a load!) at Comdex in Atlanta back in the 1980's.  Very impressive!

kenw1213
User Rank
Iron
Flat, safe lithium polymer battery
kenw1213   7/28/2011 3:43:05 PM
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Ahhh, I remember the company now.  They joined with Dow to form Dow Kokam Battery.  Kokam has a patented construction method that keeps the battery "safe".  I recall seeing a demo video.  Check out http://www.dowkokam.com/tech-cells.htm

kenw1213
User Rank
Iron
Re: Flat, safe lithium polymer battery
kenw1213   7/28/2011 3:51:24 PM
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www.youtube.com/watch?v=-l9reROfBF8

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