I have a 2250mAh 11.1v 3 cell battery that I'm using for my 450 kit build, motors are 1000Kv motors. 

Using a Pixhawk with the PX4v1.3.3 flight stack, loaded via QGC.

And I'm using an Imax B6 charger for the battery. Battery is brand new.

This is the issue; I will plug the battery in, with the props off, as a system check. I can throttle it up all the way, no problem. QGC says batteries are at 100%. External voltage meter says all 12.1, no1 4.03, no2 4.03, no3 4.06. 

System check looks good, so I put the props on.

I get the UAV up and within seconds, QGC tells me that the battery has dropped to 33% and the Pixhawk battery alarms go off. The external voltage meter, that is set at 3.6, does not go off. 

I keep it up for a few more seconds and the battery level drops to 17% and the alarms go nuts. I set the UAV down, for a flight time of mere seconds. 

I will then unplug the UAV from the battery, wait a second, plug it back in and reboot. QGC will say the battery is still at 100%. External voltage meter hasn't changed. 

So with the props off I have no issue, but as soon as I put the props on, the battery can't seem to handle it.

What am I doing wrong?

Thanks you for any insight.



Views: 1736

Reply to This

Replies to This Discussion

I have my props labeled properly, so that I mount them correctly, and I can assure you that the motors are spinning in the correct direction. If there was a miss mounted prop or an incorrect motor spin the quad would flip. It spins flat.

Guess I'll double check everything and recalibrate.


It wont necessarily flip. I know cause I had a flat spinning drone that would escalate quickly. It can have one motor moving air down, but its backwards and causing yaw to be wrong.

HAHAHA, I've certainly cursed that same line during my progress through the hobby trying to build my Hexacopter. I can assure you that once you get things working and flying well, especially with the ability to do Autonomous missions, it will be worth it! Hang in there!

mark bellncula said:

To all those people who bought DJI's and flew them out of the box... I hate you. 

Counterclockwise rotation results from more force from the props that rotate counterclockwise compared to the props that rotate clockwise.  Most of the time it comes from an upside down prop, but anything that reduces power from one motor can cause this.

Since you know, without a doubt, that the props are correct, motors all spin in the correct direction, and the motors are all assigned correctly (esc wires are not switched around) THEN you need a bench test.

Without the props installed, arm the drone in stabilize mode and hold it up in the air, run the motors at a slow speed.  Tilt the drone, left, right, front, back,You should be able to get some idea if the motors on the lower side of the drone increase in speed as the motors on the higher side slow down.  These motors are designed to be run under load, so don't push it,  don't run at full speed, and only for a very short period, like, a minute or less.

Some people condone this type of test outdoors with the props installed, so as you hold on to the drone as the props are spinning you can feel the direction the drone is pulling.  This may work well but its very dangerous.  If you consider it, you should have someone else hold the drone while you operate the controls.  I was cut trying this by myself and was very lucky, I will not do it again, however I have a big heavy drone, smaller, lighter, may work without such risk.

The object of the test is to physically see and understand the responses by the drone.  Your issue should become apparent. 

Reply to Discussion


© 2019   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service