Help needed!
 

Hi all

I have been flying electric for about 2 years. Problem being with only 1 aircraft/setup. I have the Extreme flight edge 45" and it came with an airboss 45A ESc and Torque 2818/900 motor. I coupled this with a Turnigy 4400mah 15c lipo. This setup has worked for the duration and I have had great success with it.
Problem:-
I recently bought a new aircraft and have kitted it out myself(with what i though was correct) I bought a turnigy Plush 30A esc and a Turnigy C2826-1900 motor. coupled with a 2200mah 20-30c lipo. i have tried this and black smoke came from the esc! everything was set up as normal. The motor turned for approx. 5seconds then quit.
I tried it again some time later and although it still beeps as per instructions it cant seem to turn the motor.
Have I done something wrong? Is there a formula to follow for future reference?
I have heard that you should multiply the mAh by the discharge current but this theory seems to fail my extreme flight.
eg: 4400mah x 15c = 66000 which would mean I would need at least a 80A esc. But it flies perfectly well with a 45A esc?

Hope this makes sence
christian

RE: Help needed!
 

Either too much prop or not enough ESC. No way to know without knowing the details of the plane and prop.

RE: Help needed!
 

I bought the Hobby city cessna. Its 44 inch wingspan and made from balsa. Prop is a 9x4 electric. Both bought from hobbycity.com
Cheers

RE: Help needed!
 

The formula you cite, battery capacity x "C" rating, tells you only that the battery is capable of providing up to 66A of current. That doesn't mean the power system will USE 66A. It only means that according to the battery manufacturer, the battery can provide that much.

You did not say whether the battery used when the ESC was damaged is a 2-cell or a 3-cell lipo. If you look at the specifications for the motor, they say the recommended prop on 3 cells is 8 x 4. Were you using a 3-cell lipo with the 9 x 4 prop?

For a given motor, a large prop will draw more current than a smaller one. If you used a larger-than-recommended prop, you may have caused the motor to draw excessive current, which in turn was too much current for the ESC. Whenever you depart from the manufacturer's recommendations, you are into the realm of experimentation. A wattmeter is a mandatory piece of equipment when you are experimenting with electric power setups. Without a wattmeter, you are merely guessing.

- Jeff

RE: Help needed!
 

The first time I tried this the prop wasn't on. I used the 3cell lipo 2200mah. It didn't seem to start. The esc sounded a few times then after some tweaking it started for approx. 5 seconds then smoked and quit. It hasn't worked since. This was all done on the bench and not in the air thank God!.
Any reccommendations on a differend esc or a smaller 2cell lipo?

Christian

RE: Help needed!
 

I'm not familiar with the turnigy motors but, if the 1900 part of the model number refers to the KV rating, then that is very high for a model like yours.  Normally you would use a motor with 1/2 that KV rating or so.  The high KV motors are normally used for helicopters and edf jets.  We normally use slower motors than that on model propeller planes.  You will want to check that out.  If you have a high KV motor then you need a very much smaller prop.

If you burned things up without a prop then either you ran it too long on the bench (inadequate cooling) or you have a bad component.. </p>