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Power pack C, two motors not pulling the same.

Hi Gang. First post!

I’m writing because I just maiden flew a Seaduck build and had a hard time keeping it under control. It was obviously pulling maybe twice as hard on the port engine. This is my first experience with a twin motors.

-I attempted to try for matching in the mix but it was not consistent.
-yes I calibrated esc’s.
-yes to counter rotation and matched props.
-Also happens with no differential thrust mix, same values to both esc’s.

Should I be trying an FC with oneshot 125 to get a guaranteed match between the two motors?

Do I just have a bad motor? Should all motors passing qc pull exactly the same if wired in parallel and given equal calibrated pwm signal?

I had a lot of fun making the Seaduck. It’s a great project. Luckily it just barely fits in the back seat of my car. If the wings were 1 inch longer, no dice.

Thanks in advance!

Just an update. I changed a motor and the problem persists. Bad ESC? It seems like one of the ESC is acting like it’s on Emergency low power mode as if it’s a low battery. Problem is not apparent at first but builds after a minute of running.

I hope to get s response.
Never built a twin but one idea I can think of is to try to trim it using the rudder trim button. I think it trims the rudder and the diffential thrust. at the same time. If you keep having problems try contacting Flite Test customer service if you ordered it from them and think it is a problem with the esc. Btw are you powering it with one or two batteries?


Well-known member
At first glance it sounds like a bad ESC, particularly as you have changed the motor on that side but the problem persists. Regarding your observation about the low power mode, this might happen if the voltage cutoff setting for the ESC was set too high. It can also happen if the ESC is damaged (I have a pair of 3S ESCs that were matched but I accidentally plugged one of them into 4S once and although the ESC still works, it's about half the power of the other one).

What type of ESCs are you using?
When you calibrated them, did you use a programming card or the Transmitter.
Any danger you entered programming mode on the ESC when calibrating and you inadvertently changed other settings like the low voltage cut off?