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Old May 05, 2012, 01:52 AM
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Joined May 2012
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Quadcopter, 1 motor runs a lot faster than other 3

Im attempting to build a quadcopter for the first time using the microchip PIC18. I successfully programmed the 6-amp ESCs using a 1-2ms pulse every 20ms. The only problem is when I try to run all motors, only 1 is as fast as i need it to be, the other 3 are very sluggish and eventually stop altogether even when sending all ESCs the same pulse. Also, other times all 4 motors will seem to go there max speed for a little bit on start up and then quickly level off to a speed that does not lift the copter.

Could it be a battery problem? I'm new to LiPos but the one we are using is a 11.4V 1500mAh 25C battery. The voltage across the battery is very close to 11.4V still even with repeated use.

Any help or suggestions is appreciated!
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Old May 05, 2012, 02:39 AM
Emress
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United States, SD, Rapid City
Joined Nov 2011
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you should read this and hope that you dont screw up your LiPos(you probably haven't yet). a full charge would help(12.6v)
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Old May 05, 2012, 05:16 AM
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United States, AZ, Scottsdale
Joined Sep 2011
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Try to calibrate your throttle range:

1) remove all props
2) connect esc to throttle channel of rx
3) turn tx on, apply full throttle
4) plug in battery and wait for esc to beep
5) reduce throttle to zero and wait for confirmation
6) repeat for each esc

Maybe reflash your ESCs with Simonk firmware
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Old May 05, 2012, 05:32 AM View Post
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Old May 05, 2012, 05:38 AM
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Joined Feb 2008
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Well, i would suggest to check the k/v of each motor first, at the end, you may sit on some wrong delivered or produced motors, sold with the same kv. Also check if they do not have a short in windings.
kr
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Old May 05, 2012, 12:51 PM
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What are the the recommended programming settings for the ESCs?
I'm using 4 of these: http://www.hobbyking.com/hobbyking/s...idProduct=4318

and these are the motors: http://www.hobbyking.com/hobbyking/s...otor_19g_.html

Also for the ESCs I've read that all get hooked up to the battery terminals and all get a signal line and ground but only 1 gets a 5V line? Is this correct?
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Old May 05, 2012, 01:00 PM
Emress
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United States, SD, Rapid City
Joined Nov 2011
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Brake off
Ni-xx
Soft-Cut
Low Cut off
Normal start up mode
Timming depends.

get a battery monitor, or make sure the battery doesn't drop below the recommended voltage. or use Li-xx on the ESCs which enables low voltage cutoff.

Quote:
Also for the ESCs I've read that all get hooked up to the battery terminals and all get a signal line and ground but only 1 gets a 5V line? Is this correct?
if your ESCs have linear BECs, then you can leave all the +5v connected, if they are switching BECs, you need to unconnect all but one +5v. yours are linear.
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Old May 06, 2012, 11:04 AM
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Quote:
Originally Posted by sirbow2 View Post
Brake off
Ni-xx
Soft-Cut
Low Cut off
Normal start up mode
Timming depends.

get a battery monitor, or make sure the battery doesn't drop below the recommended voltage. or use Li-xx on the ESCs which enables low voltage cutoff.


if your ESCs have linear BECs, then you can leave all the +5v connected, if they are switching BECs, you need to unconnect all but one +5v. yours are linear.
Why set the ESC's to Ni-xx when the battery is LiPo? Also does it matter that he's not using a BEC?
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Old May 06, 2012, 02:54 PM
Emress
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United States, SD, Rapid City
Joined Nov 2011
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so that the ESC deosnt limit the motor speed when the battery is low( can cause quad crashes). so Ni-xx disables that, and then use a external battery monitor(something like http://www.hobbyking.com/hobbycity/s...idproduct=7223) to notify you when the battery is low that way the motors can still go 100% if need be on the way down.

the bec normally supplies power to the FC; if you are using another source to power your FC, id unconnect the red(+5V) from the ESCs
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Old May 06, 2012, 11:24 PM
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ok guys so I tested the motors again without the battery, using 2 power supplies, 1 supply for 2 motors... each supply has a max current o/p of 5.5A. 1 supply was providing 1.9A and the other was providing 2.3A when under load, all ESCs were receiving the same pulse...any ideas?

I also charged my Lipo 3 cell battery today to 12.2V, I don't have a charger so i used a bench supply, the charger connector on the battery has 3 black wires and 1 red. I connected the red wire to positive and grounded the closest black wire to red, giving it 4.2V and a constant current of 1.49A... when the supply switched to constant voltage mode i then switched the ground to the next black wire over and set the supply to 8.4V, 1.49A... rinse and repeat but with 12.6V on the last. Is this the correct way to do it? After I was finished the battery terminals read 12.08V.

After this i tried running all 4 motors with the battery and they still performed poorly... I must be missing something!
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Old May 06, 2012, 11:44 PM
Emress
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United States, SD, Rapid City
Joined Nov 2011
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seems like you have some miss winded motors maybe(check the Kv). also, did you calibrate them with the TX yet?
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Old May 06, 2012, 11:57 PM
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Joined May 2012
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Quote:
Originally Posted by sirbow2 View Post
seems like you have some miss winded motors maybe(check the Kv). also, did you calibrate them with the TX yet?
Alright I will definitely check the Kv soon, thanks for the suggestion I shouldn't have ignored the first user that said that. Also, I have calibrated the ESCs a couple times, since I'm using a microchip and not a transmitter, my calibration method involves sending a 20ms signal with a 2ms duty as "max throttle" and then a 1ms duty is "lowest throttle" I don't have an ESC programmer but the beeps match perfectly for what the instructions say.
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Old May 07, 2012, 02:15 PM
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United Kingdom, Scotland, Glasgow
Joined Feb 2012
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Quote:
I also charged my Lipo 3 cell battery today to 12.2V, I don't have a charger so i used a bench supply, the charger connector on the battery has 3 black wires and 1 red. I connected the red wire to positive and grounded the closest black wire to red, giving it 4.2V and a constant current of 1.49A... when the supply switched to constant voltage mode i then switched the ground to the next black wire over and set the supply to 8.4V, 1.49A... rinse and repeat but with 12.6V on the last. Is this the correct way to do it? After I was finished the battery terminals read 12.08V.
You MUST use a proper charger to safely charge LiPo batteries. Get one that runs on 12V DC and you can power it from your bench PSU - they're not that expensive. LiPos have strict limits on max cell voltage and you've probably overcharged the battery using just a bench PSU. If you insist on using the bench PSU, then charge each cell separately to exactly 4.2V using limited current. You were charging the first cell by itself, but then charging it again with the second cell in series, then charging the first 2 cells again in series with the third. Not good. Serious overcharging can actually cause LiPos to burst or catch fire, and even mild abuse can shorten their life substantially.
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Old May 09, 2012, 12:48 AM
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Joined May 2012
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Alright guys, so I re-charged the Li Po today the correct way and got all cells to about 4.1V, and guess what? All motors work great now! some are still faster than others but I'm guessing that's just the crappy Chinese manufacturing.


By the way, has anyone worked with Wii sensors in nunchuck pass through mode? I aways get all 1s returned over the i2c bus...
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Old Jan 17, 2014, 01:00 PM
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Joined Jan 2014
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i make quadcopter par wo fly nhi kar pa raha hai wo ek taraf se upar uth raha hai please help
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