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Dec 24, 2002, 01:30 PM
D W
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How to get started in Li-Polys?


Happy Holidays All,
I fly Parkflyers almost exclusivly now and it has been suggsted at their forum that I might want to try Li-Polys. Have been converting rubber kits, well actually 1 so far (another's under the tree!) and could really benefit from weight savings.
So how do I get started? Currently using 8.4volt, 300maH NiMH and thereabouts.
What charger is best and will 'grow' with me?
I'm not big on large #s of battery packs as can usually only manage a couple of flights after dinner (don't have the spare time). So rather spend the money on quality.
Thru searches I see some Li-polys have protection circuitry built in. Is this the way to go? Though my brother and father are electrical engineers I have very limited skill and knowledge in this field. So the less I'd have to do as far as wiring, etc. the better.
And where should I purchase from??
Thanks in advance for any help.
-David-
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Dec 24, 2002, 04:45 PM
Hello DW, a two cell Kokam 1020 will replace your 8 cell 300nimh with about the same weight & performance + 3 times the flight time. There are many choices on chargers, from a 7 dollar surplus (but very limited) 2 cell charger all the way up to the $200 Orbit Pro & with many steps in between. If you would like to know more, please send me an email to: [email protected]. Thanks

-Troy
Dec 25, 2002, 11:09 PM
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Getting started


David:

Last spring I bought (2) 2 cell 950 mah packs from WildRC, plus the Potenski charger. It was the best thing I ever did. I use them now in all my GWS DX-A (EPU6) powered planes. I get 40 minutes on a charge. Now that FMA is selling Kokams, you can buy (2) 1020 cells for $25 if you don't mind soldering, or they will solder them up with a connector for a little more. Then get the Potenski charger from Hobby Lobby for $26. Also, Bishop Power Products has a recycled cell phone chargers cheap and Kokam cells.

Dan
Dec 27, 2002, 09:01 AM
Mr Mootsie
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this is exactly the kind of information I need. In the process of converting a Dumas Bearcat to electric, and I wanted to use LiPoly's in it.

One question: Can I use my Robbe Infinity 2, or do I need to go with a "special" LiPoly charger?

cheers,
tim
Dec 27, 2002, 09:29 AM
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Quote:
Originally posted by MrMootsie
this is exactly the kind of information I need. In the process of converting a Dumas Bearcat to electric, and I wanted to use LiPoly's in it.

One question: Can I use my Robbe Infinity 2, or do I need to go with a "special" LiPoly charger?

cheers,
tim
Mootsie: You must use a charger designed for Li Poly. Their numbers are growing each day. If the Infinity has a Li Ion or Li Poly setting, you may be able to use it. It will be most helpful to you if you open www.fmadircet.com, click on Support, scroll to Applications Notes and read the pdf file Applicatiojns Note 000001 re the Li Po cells. It will be instructional if you scan the many posts in this forum under Kokam Lithium Polymer Batteries. Good luck; join the fun!
Dec 27, 2002, 10:04 AM
Mr Mootsie
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no such setting on the Infinity. But it does allow me to buy more stuff. Thanks for the link.
Dec 28, 2002, 12:11 AM
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Quote:
Originally posted by MrMootsie
no such setting on the Infinity. But it does allow me to buy more stuff. Thanks for the link.
Ho! Might work better if I spelled it correctly. It is fmadirect.com
Dec 28, 2002, 07:01 PM
Mr Mootsie
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got it, and figured it out.

I am not nearly bright enough to do all the science involved. I am simply looking for someone to tell me which battery to use in my Dumas Bearcat, and how to charge it.

thanks,
tim
Dec 29, 2002, 12:07 AM
Registered User
Mootsie: You don't have to be a rocket scientist, but you have to know a couple of things. If you know how much current drain you motor/gear drive/prop demand and what voltage the motor will survive, then you can use LIPOCALC to tell you what pack to use. You can access LIPOCALC at www.fmadirect.com Click on Store, click on Kokam Batteries, then click on the icon for LIPOCALC. Enter the current draw, enter the voltage and hit calculate. The pack you describe could probably be replaced by a KOK 530 2S2P pack if current drain is in the 3 to 4 amp max range. If greater, you could go to an 860 mah size. It is a great help if you can measure static current drain for your current pack. If you go with the 530 mah 2P, that is 1060 mah and you you can expect flight time of about 3 to 5 times that for the 300 mah NiMH. You can make that choice also by using LIPOCALC. The weight of any of these packs is so low that your airplane will be indifferent to which you choose.
Last edited by electroman; Dec 29, 2002 at 12:09 AM.
Dec 29, 2002, 09:28 AM
Mr Mootsie
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that is a bit more like the information I need, thanks. Keep the tips coming.
Dec 29, 2002, 06:22 PM
D W
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Yes, Very helpful Electroman, Thank You,
HAPPY NEW YEAR
-David-
Jan 02, 2003, 12:13 PM
Take a look at J&N Performance Electric at www.jnperformance.com

They have the best pack avilable if your application is 3 amps and under which meets most GWS applications. The pack is 640 mAh 2 cell pack @ 33 grams with a very important safety that eliminates any charge or use issues. The pack is only $39.99 ready to use.

They also have a dual charger for around $62.00 will charge the packs in about 2 hours.


Good luck,
Pylonbuster
Jan 02, 2003, 12:32 PM
Mr Mootsie
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more good stuff, thanks.
Jan 02, 2003, 12:34 PM
D W
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Yup, Thanks.


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