ESC, Motor, or battery?

[2NG]

Hello flyers,

I have a Graupner 400DD, Watt-age IC-15 ESC, 9.6 V - 8cell-800mAh while running at full throttle. I noticed that the ESC cuts off at different times. The lowest time that I have gotten is 30sec from a freshly charged batteries.

I am confused to where the problem is, could it be the motor? The battery? Or the ESC. What would you guys suggest that I should do, pinpointing the problem?

Any trouble shooting method that you guys do for this particular, problem:confused: Any suggestions?

Thanks,
2NG:)

[GHMBO]

Monitor the battery voltage with a meter and see if the voltage drops to the ESC cut-off point when the ESC cuts off (motor at full speed). If the voltage is higher than the ESC cut-off voltage, suspect the ESC. If the voltage is near the cut-off point then look at battery problems.

[2NG]

Thanks, GHMBO.

Should I be connecting the meter for current at the motor, in a series. Positive to the motor and negative to the ESC?

[Dave Robelen]

Hi 2NG,
The meter should go across the battery. It should be set to read voltage. Note the reading before you turn on the motor, and then keep watching while you run the motor full speed. If the battery is the problem, the voltage will have dropped to the ESC cutoff point. If the battery is still reading fairly high when it cuts, suspect the ESC. You might also check and see if there is anything getting hot on the ESC. I would suspect the motor to be least likely based on your info.
Regards, Dave

[2NG]

Thank you guys, I will give it a shot this weekend, hopefully I will be able to locate the problem, and fly my Cub 400EP.

[2NG]

Hell all,

After a frustrating search for the suspect. I finally found it. I did the multimeter check to the motor, ESC, and battery, running full throttle, voltage dropped nearing the cut-off point then so, as you guys suggested it to be the motor, It was, it's the motor all right.

Then, why is it, when I put with a different ESC is doesn't make that same problem? Using the same motor on a different ESC.:confused:

[Dave Robelen]

Hi 2NG,
It sounds a lot like your motor is drawing more current than normal for a sp400. Binding, maybe? Perhaps the first ESC is having a problem at those currents, especially if the voltage at the battery is dropping near the cutoff level. Does the battery do the same with the second ESC?
Good luck, Dave

[2NG]

You know Dave, the more I brainstorm myself in finding the problem the more I get :confused: (hahaha) The battery seemed to be working okay, and I used it with the new ESC that I have, and the cut-off time is 5min( with new motor). Before it was 30sec, that a big difference. Okay, then so my Motor is bad, but what I am doing now, is try to figure out what went wrong. I wired it correctly.

[Dave Robelen]

H 2NG,
If the motor is bad by itself, I bet it is getting a whole lot hotter than the new one. Have you been running this problem motor and trouble came up? I would look for something rubbimg or binding, or shorting at the brushes. If it is new also, the armature may be wound with a very low resistance. Suppose you hook this motor up to the ESC without the prop and run it at part throttle for a bit. If it still acts up, you can count on mechanical troubles in the motor. If it is only with the prop on, I bet it is drawing a lot more current than normal, which would imply a weird armature wind.
Another way to compare the two motors is to connect each one without a prop to a flashlight battery while you watch the voltage. If the voltage drops much quicker with the first motor, I would suspect mechanical problems.
Good luck, Dave

[2NG]

flashlight battery while you watch the voltage.

How do you do that? How would I wire it? This sounds like a good like idea:) hey Dave, I have learned a lot from you today... I appreciate that, thank you!! I will be asking you more Questions in the future :D

2NG

[Dave Robelen]

Hi Man,
My method is to attach (solder?) two wires to the motor terminals with their ends bared. If your voltmeter has clips on the leads, you can clip these on the wires now. Then, just press the two wires against the ends of a flashlight battery. A smooth motor will go easy on the batery, while one that has a problem will start to pull it down much quicker. If you get some of thse leads from Radio Shack that have clips on both ends, this whole process can go pretty speedy.
Good luck, Dave

[2NG]

Thanks Dave, well, back to the LHS for a new ESC, the motor is good, and I followed your methods, and it gave me an accurate testing method. I flew the setup. New ESC same motor and it flew fine. Now I am back to having fun again.... Now is there a way to correct this weather? N. California is been having a funky weather. Dave, any solution to, where we can fly of an hour or two with electric's? Ohhh, well.... probably in the near future:) Thank you for all of your idea's and kind help:)

Antonio