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Old Sep 04, 2002, 11:20 AM
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Joined Jan 2002
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Lithium Polymer Batteries in Foamies

The following posts are from the "Modelling Science" forum, in the "Kokam Lithium Polymer Batteries!" thread.

These batteries are very thin, but wide and long. They offer great power density, but the higher-capacity cells present problems fitting them into airplanes. For example, the Kokam 3270 mah cell is 3.7" x 2.5" x .205" (2.2 ounces).

How we gonna fit'emin (foamies - flying wings, in particular)?

Anybody tried to bend these cell a little, to follow the curve of an airfoil?
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Jube T Cornpone - Member

“… you could about cover the wing with paralleled 45 mah cells, they are so thin!” (electroman)

“ …We're going to have to squeeze these cells in the wings of our planes so we will have room for them.” E-sailpilot 86)

That'll be the only way to go with most foamy flying wings - the FMA Razor (now unfortunately discontinured) is the only one I know of with an equipment bay large enough to accomodate LiPolys 1000 mah & up, in their contemporary thin profile.

I plan to use the router attachment on my Dremel to flush mount a pair of Kokam 3270s, one in each wing, on a Zagi

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opualuan - www.thebuckshop.com: 1842

make sure to put a ply panel or something to cover them up... don't want to scrape them landing on a rock...


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Jube T Cornpone - Member

Going to take the last 2 posts to "Foamies', and continue there as new thread: "LiPolys in Foamies".
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Old Sep 04, 2002, 12:34 PM
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Joined Oct 2001
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The 3270's will fit some planes (I stuffed them into my Zero ok) but like you pointed out, they will not fit in to most fuses. I think the real way to go is running a parallel via a Y connector setup. The 1575 cells have a much smaller footprint - 4 cells are a bit smaller than a 8 cell 600ae pack so they will fit most planes & wings no problem. Plus you can always separate the two packs to run a single pack in a even smaller plane that does not need 3000+mah. I am testing the parallel setup now & so far the results look great. I am building an X-bow foamy that will use a speed 400 & 480 motor and the parallel 1575 cell setup for the in-flight tests. Should net 30+ minutes with the stock speed 400 and close to 20 for the 480 setup.
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Old Sep 04, 2002, 01:11 PM
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What about some of these Mininwings? Like say the "Swift" Or acers Minispeed wing? WHich one is it that is already using the Li-on pack? WHat size is it?
I am looking for a pack relitively the same size as a four pack of "AAA" cells(in series of course) WHich one would this be? I sure wish we had some photos of what these packs look like.


Mal
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Last edited by kushal_22; Sep 04, 2002 at 01:22 PM.
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Old Sep 05, 2002, 09:58 AM
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Mal - I don't know the exact answer to your question - maybe nobody does. These cells are pretty new and still being adapted in all kinds of ways by different flyers. I doubt there is a standard, best way for the small wings yet.

Try >http://www.rcgroups.com/forums/showt...threadid=56590<. There are discussions of several sizes of Kokams with dimensions, weights, and pictures there.

Also. asperkins and others have used Qualcoms, and reported on them in the "Parkflyer" forum.
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Old Sep 05, 2002, 12:54 PM
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Thanks for the help. I am sure one of these packs if not a couple will be usefull in these wings. I also have a Tinabob that one of these Packs is going to come in usefull! These Planes are just tooo cool. If no one has seen the tinabob go to www.foamfly.com there is some video there and plans will be up there shortly.

Mal
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Old Sep 05, 2002, 09:36 PM
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Mini Wings and Li

Mal,
I use the Qualcomm 830's in the mini wings such as Acer's Mini Speed Wing and my own wing design and get over 20 minutes of full throttle. The Li's don't give as much "punch" as the 300 NiMH but its more than adequate for my uses. The Tinabob also uses the Qualcomm 830's driving a pair of the GWS 50XC.

I have tested the Qualcomms on 2 GWS 50XC and it should give about 10 minutes of flight. I'm in the process of creating a 2 motor version of my "Mini E-Wing".

I'm interested in the new Kokams but I may also try the Ultralifes. I have the latter but haven't tried them yet but from posts, it should perform better than the Qualcomms in a 2 engine config as in the Tinabob and they are also about half an ounce lighter than the Qualcomms albeit slightly less capacity.

Hank
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