Quad motor not starting. ESC maybe? - RC Groups
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Jan 22, 2013, 06:34 PM
Registered User

Quad motor not starting. ESC maybe?

I have a vid to show what's going on. Basically, all motors idle up normally except one. This one happens to be the recipient of a brand new esc. I have calibrated 3 times but the issue remains. I can rapidly go to full throttle and back and it will kick start the affected motor and as long as i don't go back to zero throttle, it will fly just fine. Can anyone tell me what is going on?

Multiwii pro 2.0
20A House ESC all from Witespy.

Multicopter with bad ESC possibly (1 min 10 sec)
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Jan 22, 2013, 08:19 PM
Registered User
Dodgy solder joint somewhere.
Jan 22, 2013, 08:20 PM
Registered User
Is the new ESC identical to the old ones? You don't mix ESC's in a multi rotor so if it's not identical that'll be the reason. Even if it's the same make/model it may not be the same ESC underneath the shrinkwrap
Jan 22, 2013, 09:10 PM
Registered User
I re-soldered the esc to the power distribution board but that doesn't mean something isn't loose on the FC. I'll check that out.

It actually looks different but Witespy says it is the same under the shrinkwrap.
Jan 22, 2013, 09:11 PM
Registered User
BTW the problem is only when starting the engine, once its going i can complete an entire flight without any problems at all.
Jan 22, 2013, 09:54 PM
MayMayDay's Avatar
Definitely one of those bullet connectors between the ESC and the motor. That twitching is because it can't get the timing through the loose connector to keep it spinning. Had that issue with one of my ESC/motors. Lightly tugged on one of the bullets and the wire popped right out.

As to why it works at high throttle, my guess is that once it gains momentum, the 2 phases of the ESC can keep it spinning even though the 3rd is failing because of the bad connection.
Jan 22, 2013, 10:54 PM
Registered User
Mortimer's Avatar
Originally Posted by Spacenutz
20A House ESC all from Witespy.
Verify solders on your ESC: https://www.rcgroups.com/forums/show...&postcount=475
Jan 23, 2013, 10:04 AM
Registered User
That makes sense Mayday. I think i'm just going to ask if Paul will refund that esc.

Thanks Mortimer. That's is exactly what has happened to 3 of my esc's now. The pad gets ripped off and i can't get it soldered back. I may try the hot glue on the two remaining escs so they don't fail too.
Jan 23, 2013, 11:30 AM
MayMayDay's Avatar
Do a switch check to make sure it's the ESC. i.e. run the motor on a different ESC and run the ESC with a different motor. If the problem follows the ESC you have a pretty strong case for returning it.
Jan 24, 2013, 07:04 AM
Registered User
I switched out a brand new spare motor and it did the same thing. I'm just waiting on a response now to return the esc. Thanks for all the help everyone.
Jan 27, 2013, 08:53 AM
Registered User
I got a new set of HK esc's, flashed them with simonk and now everything works perfectly. I guess it was the bullet connectors on the old esc's. It also fixed a jumpy throttle problem i was having. Its nice to be back in the air thanks for everyones input.

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