Batteries For Electric Motors

[Midair]

Hello All:

I'm just breaking into the world of electric powered aircraft after more than 25 years of glow driving and I have a question about batteries. I recently purchased a "full house" Global Decathlon (28" wingspan) and will power it with a Speed 400 brushed motor, geared 2.33:1. The motor has a nominal voltage of 6 volts, but is designed to run at 8.4 to 10.1 volts. Recommended power is NiMH seven cell, 8.4 volt pack. I'd like to instead use the new Li-Po batteries, but my only choices are the 2 cell 7.4 volt or the 3 cell 11.1 volts packs. Can I safely use the 11.1 volt pack or am I restricted to the 7.4 volt pack. Is 7.4 volts sufficient for the system? Your help and advice appreciated.

Peter

[matteo]

Hey Peter,
I've run 3s on a direct drive speed 400 but it was a 7.2 volt motor. I would go with whatever the manufacture recomends because Im afraid that a 3s would burn out the motor and a 2s wount be enough power.

Matteo

[Flybaby]

I had a GWS geared brushed motor and tried my 3 cell lipo on it and it was too hot. About one flight and the motor was starting to smell. So much for that idea. If you're going to stay with a brushed motor go with the 2 cell lipo. Better yet go brushless. Once you go brushless, you'll never go back. I love my Axi2212/34 with 3 cell lipo. Hauls my 16 oz scratchbuilt Speed400 straight up.
It's a bit more money to start with, controller and motor but the performance you get is well worth it. Assuming you already got over the shock of the lipo and charger prices. Happy flying!