charlied123

I just bought a Formosa with a 7 cell 730 mah ni mh battery pack for a ICS 300 J ESC with a GWS 4n receiver. If I went to a Li-PO 900 Mah pack, Should I use two cells or three and Why. []

crashingagain

Where are you getting 900 mah cells? Unless they are high discharge cells you will probably ruin them in a formosa. Get ThunderPower 1320s or some Kokam 1500s. On 2s 1320s your plane will have roughly the same thrust but you will lose weight which gives you more power. On 3 cells, unless you prop down or use lots of throttle management you will smoke the motor pretty quick, so you are better off on 2s with the 350c that came in your plane.

Also consider replacing the speed control with a lipo friendly version like the pixie 20 or you could damage your cells

charlied123

So far I bought the Kokam 700 2 cells to replace the 730 Ni mh. I was concerned about the voltage drop from 8.4 to 7.4. Will that affect the power at all? I was going to order 1200 mah but I wasn't sure if I should get two or three cells. I guess I'll go with two if I can burn out the motor with three. Thanks.

charlied123

So far I bought the Kokam 700 2 cells to replace the 730 Ni mh. I was concerned about the voltage drop from 8.4 to 7.4. Will that affect the power at all? I was going to order 1200 mah but I wasn't sure if I should get two or three cells. I guess I'll go with two if I can burn out the motor with three. Thanks.

sierra gold

You are saving a little weight, which helps to comp for the slight voltage drop.

However, you will gain very little run time as you bought Lipos with the same mah capacity as your NiMh.

A 3S pack is not a good mix with an EPS 350, IMO. Stick with a 2S pack.

The 3S pack works well with most brushless motors.

Sierra Gold

Matt Kirsch

My Feedback: (21)

Kokam 700 cells are only rated at 6C, for a total output of 4.2 Amps continuous. The EPS350C power setup in a Formosa draws about 8 Amps, or twice the pack's continuous rating, at full throttle. Those Kokams won't last long even if you use strict throttle management. You might be able to draw 6 Amps in short bursts, but 8? No way.

The rated voltage of a 7-cell NiMH may be 8.4V, but that is not the voltage it holds under a heavy load, like it would be seeing with an EPS350C. Under that load, you'll be lucky if the battery holds 7V. If you get yourself a LiPoly that can handle the load, like a Kokam 1500, voltage will be much higher, and performance will be better because a properly sized LiPoly doesn't suffer from voltage depression as badly as a NiMH.

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2 cells or by by motor