Instructables

RC Quadrotor Helicopter

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Step 30: Repair, Re-tune, Recharge

If you crashed while flying, you might have broken some of the quadcopter's arms. There's no easy way to fix this, so just disassemble the frame and replace the arm with a spare.

After crashing, check if the battery is damaged. A damaged lithium polymer battery can explode! Immediately after the crash, disconnect the battery immediately if it has not exploded already, and inspect it before judging whether or not you can keep using it. If it's dented, bulging, bent, punctured, or cut, then dispose of it properly.

Broken propellers are easy to replace, but make sure that the shaft or motor isn't damaged. Remove the propeller first, then run the motor at a low speed to see if it's still functioning and not wobbly. If it's wobbly, then you should replace the motor, do this while not flying, or else you risk having the motor fail in mid-air which is more dangerous.

If you don't like the flight characteristics, just reconnect your flight controller back to your computer and re-tune the parameters until you are satisfied.

If you've noticed that your quadcopter doesn't stay stable no matter how hard you tune the configuration parameters, then maybe the airframe is vibrating too much for the sensors to be effective. Vibration is caused by imbalance of mass around the spinning motors. When the mass is balanced, the net centripetal force around the motor is 0. When there's an imbalance, then the centripetal force will have a magnitude greater than 0 and the angle of that force will spin. This becomes oscillation, which is vibration. So to eliminate vibration, we need to apply a force equal in magnitude but opposite in direction. Get two zip-ties per motor, and tie two zip-ties around each motor. While the propellers are installed, move the zip-ties around until the force they introduce cancels out the vibration.

Recharging the battery should sound straight forward. My charger is pretty nice and full of features, but it didn't come with a manual (I found one online later). There are two main power wires (positive and negative) that connects from the battery's main wires (the thick ones) to the charger (two banana plug jacks), connect those in the correct orientation. Then plug the JST balance connector from the battery to the balancer jack of the charger. One characteristic of lithium polymer batteries is that each cell must be monitored and balanced with other cells during charging, hence why your battery has 2 different connectors.

Place the battery into a Li-Po bag (it's a fire-proof bag you can buy that's designed for charging lithium polymer batteries), or put them into a cooking pot like me. On the charger, select the lithium polymer charging routine, set the number of cells to 3, and start the charge cycle. The process should be automatic but you should not leave the battery un-attended during charging.

If the charger can charge at 6 amps, then get a power supply that can handle 6 amps (I use a laptop power adapter). Most ordinary wall adapters cannot handle that much current, do not make that mistake.

Please charge at 1C or less, this means if the battery is 5000 mAH, then you can charge at 5 amps, but if it's 2200 mAH, then you can charge at 2.2 amps. Maximum Current divided by Battery Capacity equals C rating. For more info, read this guide on lithium batteries.
 
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mahsa arian2 years ago
its VERY nice
kiss

i think it is can fly 5min!
or
4min..
lukeD2 years ago
I got two questions,
how long can it fly?
how much will it cost to make it?