Mikrokopter Quad XL conversion - All 4 MK3638 motors wont spin properly!

[Malcr001]

OK I recently converted my MK L4-ME to the quad XL version. The problem I have is my motors simply wont spin properly. Sometimes one of the motors spins but it does not increase in RPM this behavour altenernates between different motors at times. The rest simply twitch continuously. Ive also noticed that on powering up the quad sometimes not all the motors beep. The FC, BLC's, naviboard everything has green LED's.

Things I have checked so far:

- Check to make sure the FC is recieving the input from all control on my rc tx
- Power up quad on new lipo
- Check connections between esc contact and wiring connecting motors with multimeter
- Connect old motors to quad to verify good connection
- Check for any errors reported in mk tools
- Start quad without navi and MK gps board
- Wait for gps lock before starting throttle

My setup:
Quad XL PDB
4x MK3638 motors
V2.0 BLC's
MK FC 2.1ME

I am at a loss here I'm pretty sure I have 4 bad motors. I bought them from holgers shop but I shortened the motor wires and soldered on bullet connectors. Some may say well maybe you soldered on the bullet connectors onto the motors badly. This may be possible but I dont really think this is the cause because I should have atleast 1 motor working fine. I guess this is my last thing to try.

Would holger accept a returns on motors that have the cabling shortened? I have got to be extremely unlucky to have NONE of the motors working properly.

Before I think about returning them does anyone have any ideas on what else to try? Should I remove the C clip from the motors and check the connection inside the motor?

 

[RTRyder]

OK I recently converted my MK L4-ME to the quad XL version. The problem I have is my motors simply wont spin properly. Sometimes one of the motors spins but it does not increase in RPM this behavour altenernates between different motors at times. The rest simply twitch continuously. Ive also noticed that on powering up the quad sometimes not all the motors beep. The FC, BLC's, naviboard everything has green LED's.

Things I have checked so far:

- Check to make sure the FC is recieving the input from all control on my rc tx
- Power up quad on new lipo
- Check connections between esc contact and wiring connecting motors with multimeter
- Connect old motors to quad to verify good connection
- Check for any errors reported in mk tools
- Start quad without navi and MK gps board
- Wait for gps lock before starting throttle

My setup:
Quad XL PDB
4x MK3638 motors
V2.0 BLC's
MK FC 2.1ME

I am at a loss here I'm pretty sure I have 4 bad motors. I bought them from holgers shop but I shortened the motor wires and soldered on bullet connectors. Some may say well maybe you soldered on the bullet connectors onto the motors badly. This may be possible but I dont really think this is the cause because I should have atleast 1 motor working fine. I guess this is my last thing to try.

Would holger accept a returns on motors that have the cabling shortened? I have got to be extremely unlucky to have NONE of the motors working properly.

Before I think about returning them does anyone have any ideas on what else to try? Should I remove the C clip from the motors and check the connection inside the motor?

Before doing anything else you may want to connect each motor direct to a standard PWM speed controller and connect that to the throttle channel of a receiver, plug a lipo into the ESC and see if the motor spins up when you increase the throttle. If they do then obviously the motors are OK and the problem is elsewhere, if not try resoldering each connector and try again. I have only had one or two bad motors out of a hundred or more that I've bought and used on multirotors, I find it hard to imagine that you could get 4 in the same batch.

The symptoms you describe lead me to believe that you have one or more phases not making the connection from the BL FETS to the motor windings, that would indicate connection/soldering problems somewhere in that path.

Ken

 

[Malcr001]

Before doing anything else you may want to connect each motor direct to a standard PWM speed controller and connect that to the throttle channel of a receiver, plug a lipo into the ESC and see if the motor spins up when you increase the throttle. If they do then obviously the motors are OK and the problem is elsewhere, if not try resoldering each connector and try again. I have only had one or two bad motors out of a hundred or more that I've bought and used on multirotors, I find it hard to imagine that you could get 4 in the same batch.

The symptoms you describe lead me to believe that you have one or more phases not making the connection from the BL FETS to the motor windings, that would indicate connection/soldering problems somewhere in that path.

Ken

Thanks Ken, I will try this next.

Something in the back of my mind is saying that maybe its down to the connectors I'm using between the esc's and bullet connectors that connect to the motor. Is it possible if these cant handle a lot of amps that something like this might happen? This the connector I'm talking about: http://robotbirds.com/catalog/product_info.php?products_id=1743

 

[RTRyder]

Thanks Ken, I will try this next.

Something in the back of my mind is saying that maybe its down to the connectors I'm using between the esc's and bullet connectors that connect to the motor. Is it possible if these cant handle a lot of amps that something like this might happen? This the connector I'm talking about: http://robotbirds.com/catalog/product_info.php?products_id=1743

Anything is possible. Those connectors aren't something I'd use in a high current application and I usually try to not use any connectors between the motor and ESC where practical. On MK setups I like to go with solid wire between the BL and motor using bullet connectors only when the use case requires the multi to be able to be broken down for travel.

That said I doubt that just having the connector inline would cause the motors to not start up at all, if anything problems due to not being able to handle the current load would show up after a couple minutes in flight if that were the case. I've never been a fan of the Deans connectors anyway, they're OK for light loading but when the power requirements scale up they tend to not work quite so well and for anyone that isn't skilled with a soldering iron it's pretty easy to mess up the connection points and the housing if too much heat is applied.

Ken

 

[Malcr001]

So I got a PWM esc as you said and I went through each motor powering it from lipo -> esc-> motor and I still get the same issue. Seeing as my bullet connectors were still on the motors I figured it must be these connectors then as that is the only thing left other than the motor itself so I removed the bullet connectors and soldered the motor directly onto the esc. Same thing happens! It must be the motors .

I'm not looking forward to returning these as Ive heard holger can take a long time.

 

[ovdt]

I would check for two things:

* Are the motors running on MKTool motor test? If so, do you hear any weird sound from the motors?
* With MKTool, check the copter is level or not from the 3D view. And also move the copter by your hand if it responds accordingly on the screen.

 

[RTRyder]

Another thought just occurred to me, do you have the motors mounted on the frame now, and did you try the PWM ESc test with the motor mounted? If so, check that the screws holding the motors to the frame aren't too long and shorting the windings, easy enough to take the screws out and see what happens.

Ken

 

[Malcr001]

Thanks guys for all the hard thinking. After checking, rechecking and treble checking. The problem was actually these bullet connectors. They seem to be very sensitive to either having a connection or no connection at times. Even after I practically resoldered all the bullet connectors and checked them with a multimeter sometimes one side of the bullet connector would be good but not on the other side. Once I managed to get all the bullet connectors OK I veriefied the connection with the pwm esc and multimeter but this time checking all sides of the bullet connector. Even though once this was done I still had some problems with the motor starting up although 2 motors were starting up well. So I cleaned all the bullet connectors with isoprphyl alcohol and now it seems to be good. Maybe little specs of excess flux was the issue.

I am considering removing the bullet connectors entirely as I dont want the motors acting up when I'm on the field but the way my frame is designed which its not a straight forward job. I will see if I can replicate the issue again.

I have soldered plenty of bullet connectors in my time so I was surprised that I was having such an issue with them.