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Jyuma
09-13-2005, 09:53 PM
I have just finished a J-3 Cub and have installed a 14 Cell Sanyo
2400 Nic Cad Pack, but it is quite heavy. I calculate I need about 327
Watts which I can get with this pack as the complete plane weighs
in at 92 ounces including battery. Wing area is 735 sq. in. The motor
is an Axi 282610. So far I have never used Li Poly cells ..... what
would be the right choice as a substitute for the 24 cell ni-cad pack ?

Tks for your advice.

Jyuma

Commander_Drake
09-13-2005, 10:49 PM
14 x 1.2 = 16.8 Volts

16.8 / 3.7 = 4.5 LiPo cells in series

Looking at the specs table for the Axi 2826/10 they show 4S2P LiPo cells generating 350 to 440 watts depending on prop etc. (www.espritmodel.com (http://www.espritmodel.com))

Matt Kirsch
09-16-2005, 05:14 PM
14 cells, or 24?

Here's a quick rule of thumb, in two parts:

A. For every 7 NiCd/NiMH cells, replace with a 2S LiPoly
B. For every 10 NiCd/NiMH cells, replace with a 3S LiPoly

Break apart your NiCd pack into 7 and 10-cell chunks, or as close as you can get.

For a 14 cell pack, you would replace with 7 + 7 = 2S + 2S = 4S LiPoly.
For a 24 cell pack, you would replace with 10 + 7 + 7 = 3S + 2S + 2S = 7S LiPoly