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[6705russell]

Ok lads its getting late and this one is baffling me, i have two Torpedo 850 motors controlled by two Mtroniks 20 amp controllers, on there own operated via one channel on the transmitter they work fine independantly, when both are connected on seperate channels one motor will start up and run to half speed before the other one will kick in?

Both controllers were set up together so when throttle is applied the lights are in sync and are controlled off a Navy twin stick so both should start at the same time?

Anyone had similar problems?

Thanks in advance

Russ

[malcolmfrary]

If you transpose the motors, does the poor starting stay with the ESC or the motor?  Just thinking aloud.

[Umi_Ryuzuki]

A couple possible issues.

The Mtroniks may not be balanced for  equal forward and reverse power settings.
The Reverse in many ESC is often only 60-80% of forward.

If you are running counter rotating propellers then one ESC may be running in Reverse.
Just flipping the servo reverse function to get FWD instead of wiriing the motor for counter rotation may cause this.

Another suggestion has been that a motor wired for reverse operation is mis-timed. 

[gromarlie]

Do you still have the same symptoms if you connect both controllers to the same channel with a Y lead ? If so it's a transmitter problem - if not   

[6705russell]

Thanks for the tips guys, i dont think its the servo reverse because i have an identical set-up in my tug which works fine, if i connect both controllers to a y-lead i still have the same problem?

Russ

[victorian]

I have a similar sounding problem with two Viper 15 ESC's running large 11 pole hydraulic power pack motors (similar to car heater motors) in a two shaft setup. One motor will run properly but the other will kick and fail to start until full stick. Swapping ESC's between motors moves the problem to opposite motors. Swapping Rx channels makes no difference. The problem is worse in 'forward' drive - the motors run normally in reverse.

What's really wierd is that these ESC's have BEC feature and it the ESC providing the BEC is the one that runs properly. Disconnecting both BEC's and running the RX from a seperate battery causes both motors to kick and stall as described above. Connecting both BEC's to the RX (verboten I know!) allows both motors to run normally but still with some kicking. So it seems that the BEC is somehow affecting ESC operation.

Decoupling capacitors etc have no effect. It may be that the ESC's are current limiting and shutting down, causing the kicking, but that doesn't explain why the provision of RX power from the BEC almost eliminates the behaviour.

Advice anyone?

[stallspeed]

David,Russell
It's the one of the drawbacks of speed controllers with fast overcurrent protection.The torpedo 850 has a stall current of greater than 70 amps at 12 volts so the drive transistors shut off.The other thing controllers with current protected transistors don't tolerate is low voltage.
David,the only cure is to prevent the high surge currents and you can do that by inserting a power choke rated at your motor current,on at least one motor wire.