heliguy02

HELLO EVERYONE,
I am converting one of those walmart gliders and I am having trouble with my motor. Once it gets to about 75% throttle it starts stuttering. Reminds you of a gas engine misfiring. The setup is a speed 400 motor, Jeti 50 amp speed controller, 9x7 prop, and a 7.2volt 900 mah battery borrowed from my fighter bird. I don't have anyway of checking the amps so I am not sure how many amps it draws. If I remove the prop and let it run with no load it doesn't do it. Any suggestions??

Woody 51

Is there a gearbox fitted or is it direct drive?
If direct drive, I would say that its heavily overloaded with a 9 x 7 prop.
Also, a 50 amp ESC is awfully big for that set up.
I have a Speed 300 turning a 9 x 6 thru a 5:1 gearbox. It draws around 5 amps! I use an 8 amp ESC.

Vortran

My Feedback: (1)

My best guess is that you are not getting enough voltage from your battery. The speed controller probably gets confused if the voltage drops too far. This makes a lot of sense because you are drawing way more current from the battery when the prop is mounted.

Monitor your battery voltage will you test your power system and I believe you will find that when the motor "stutters" you're likely not getting even 5 V out of the battery. I think the battery is overloaded.

I would guess you need way more than 900 mAh on a NiCd for a speed 400. I would try a 1500 mAh or higher 3-cell Li-po.

Mike (a.k.a 'Vortran')
Milwaukee, WI - USA

heliguy02

Thanks guys for the input. Woody 51, It is direct drive motor. The speed control is big,but one I already had laying around that is why I was wanting to use it.
Vortran, What you are saying does make sense. I will see about finding a better battery.
Thanks again

wreck_em_all

If the prop is too large or battery too small for any given EP setup, high throttle settings can pull battery voltage below acceptable ESC operating conditions. This is the most likely cause of your problem. Try a smaller prop or larger battery (more mah) or both.

3DSAVAGE

I had the same problem with my GWS Formosa. It's probably that your drwing too much amps from the battery. When the battery is overstressed the esc makes the motor stutter. Try swapping batteries or something...