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Proper ESC for LI-POLYs

Old 03-12-2004, 09:13 AM
  #1  
ALA_TOM
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Default Proper ESC for LI-POLYs

I've been flying glow powered planes and helis for almost 30 years and now find myself a beginner again in the electric arena so I need some advice.

I bought a GWS Tiger Moth with the IPS100 motor and the GWS ICS50 controller. Before flying it, I also bought the Triton charger and a 2 cell, 1200mah li-poly pack. No trouble charging but I seem to get fairly short flight times (maybe 15 min over a couple of flights) before the motor gets pretty weak. This is all on one charge. I have not run the motor completely to the cut-off stage. As I have read, I should get about 45+ minutes with this pack.

My questions are:

Is the ICS50 (2 amp) too small for my li-poly pack? Maybe overheating?

Should I invest in the Castle Creations Pixie7P for the adjustable cut-off feature to protect the batteries from extreme discharge?

Thanks for the help!

Electrics are putting some fun back into the hobby!

ALA Tom
Old 03-12-2004, 11:03 AM
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sierra gold
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Default RE: Proper ESC for LI-POLYs

There are about 72 amp minutes in a fully charged 1200 mAh pack. To get 45 mins. out of that pack you would have to draw and average of 1.6 amps. It would seem that with good throttle management , 45 mins. would be possible.

I don't own a TM, so this is theory, not practical experience.

The performance of the motor will fall off as the voltage drops with use.... you start with a fully charged 8.4 volts and work down towards 6 volts.

A programmable ESC to set the LVC to 6 volts(2 cell pack) is a good investment.

Sierra Gold
Old 03-15-2004, 08:20 AM
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Matt Kirsch
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Default RE: Proper ESC for LI-POLYs

There is nothing special about a LiPoly that would make it "too much" for that ESC. The voltage from the LiPoly is about the same as a 7-cell NiMH that you'd normally be running, so the current will be about the same.

Since your Tiger Moth should fly at least 30 minutes on that setup, there is something seriously wrong with your setup. Did you put an extra-large prop on it? Is the motor or gearbox binding?

You say there's "no problem" charging it. How did you determine that? Lack of "fireworks" does not necessarily indicate that the battery was properly charged. Are you using the right settings? You should be using a voltage setting of 7.4V and a current of 1.2 Amps on the Triton. A fully charged 2-cell LiPoly should read 8.4 Volts on a digital multimeter. The Triton is a bit conservative, and only charges them to 8.2 or 8.3 Volts, which is still 80-90% charged.

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