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FT Gremlin extremely underpowered, help!

#1
Hello I bought a flitetest gremlin that one of the founders, Matt, had built for me at flitefest 2019. The quad was great and zippy for a few weeks but then began getting sluggish and have no punch. The batteries are not the problem because I use them in other planes and they work great, and charge fine. The flight time is still multiple minutes, but takes around 80-90 percent throttle to keep it steady or gain altitude. Its main problem is speed and punch. Also i’ve tried 3s instead of 2s and doesn’t help much. I have the controlled binded correctly and the settings as far as I know are correct. Anybody have thoughts on this?
 

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FDS

Well-known member
#2
The motors could just be deceased. They do wear out over time, quads need more thrust just to stay up, so they put more strain on the motor. Those are not old in time but it depends on how many hours are on them.
You could try a new set, provided they are the same spec you can just solder the new ones in.
The other thing it might be is the batteries are worn out, just because they fly fine in a plane doesn’t mean they are OK for quad use. Think about it, a quad needs at least a third throttle on 4 motors just to get and stay airborne, that’s a whole lot more power drain than a fixed wing, where it just has to keep the single motor moving fast enough to stop the wing stalling.
You can check the internal resistance of the pack with some fancy chargers, otherwise a high drain leading to voltage sag is a very big indicator of battery degradation.
I would get one brand new high discharge quad battery to test it with, then consider new motors.
My money would be on battery first.
 

ElectriSean

Eternal Student
Mentor
#3
I would suspect a damaged motor if you didn't notice much difference between 2s and 3s. Your overall power is limited by the weakest motor as the FC tries to provide the attitude you command. Make sure they all spin freely by hand. If so, you can spin them up individually using the motors tab in BF to try to compare.