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Thread: Two ESC's, Two batteries, Two motors....why...

  1. #1
    Join Date
    Oct 2010
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    Default Two ESC's, Two batteries, Two motors....why...

    ...when I hit the throttle does one motor start spinning before the other. This is the rig. Spektrum MR3000 RX which has two throttle inputs. ESC's are Sea King 180's with extra caps. Running on brand new 6s 5200 batteries. Once the boat is moving the difference seems to be not noticeable. The boat hauls ass and I know both motors are running at 100% because I know how it acts and sounds when one is slower back when I had a bad battery one one side a while back. Just wondering why the timing is different on start up.
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  2. #2
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    Apr 2007
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    AZ
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    Try using a “Y” harness to connect the ESCs to the receiver. I assume that both ESCs are programmed the same...



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  3. #3
    Join Date
    Jun 2012
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    ny
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    Quote Originally Posted by Fluid View Post
    Try using a “Y” harness to connect the ESCs to the receiver. I assume that both ESCs are programmed the same...



    .
    J T, don't both motors have to have the same build date on them? Maybe the windings are a little different.

  4. #4
    Join Date
    Oct 2017
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    LS
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    103

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    Quote Originally Posted by ScarabChris View Post
    ...
    Once the boat is moving the difference seems to be not noticeable. The boat hauls ass and I know both motors are running at 100% because I know how it acts and sounds when one is slower back when I had a bad battery one one side a while back. Just wondering why the timing is different on start up.
    The different startup is caused by sensorless speed controls.
    The ESC have to synchronize their controll algorithms and any tolerances and any minor differences result in slightly different timing.

    As you mention: Once the algorithm is synchronized it works so don't worry about the startup.

    If differences are too extreme it is usually caused by problems in the build up such as a shaft being jammed, ...

    2 drives in one boat are never exactly the same, even if the components are the same. Tolerances of the components, tolerances in the build up of the boat (they usually dominate the tolerances of the components), different electrical rotor position when starting, ...

    In the startup before the ESC is synchronized you can notice such slight differences but it does not affect driving the boat so don't worry as long as the boat behaves ok on the water.
    If there is something wrong on the water stop immediately and check the build up of the boat.

  5. #5
    Join Date
    Oct 2010
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    FL
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    The motors and ESC's were bought at the same time. The RX is the Spektrum MR3000 so there are two throttle inputs. I am not overly concerned with this one as they do seem to be synced when running and both have reverse. But now I am battleing the smaller boat, the one in my avatar. Twin older Turnigy Marine 120 ESC and two Turnigy motors. Both ESC's were bought at the same time and the motors were as well. My problem here is I can't get one ESC to get into reverse so when I need to back out of a jam only one has reverse and with those thin flex cable shafts they break easy in reverse. Having both in reverse would greatly reduce the load on the shafts.
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  6. #6
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    FL
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    Hey guys I still can't get those two Turnigy 120's to spool up together. One starts before the other and the one that starts first spins faster. This means that motor is carrying most of the load and thus slowing the boat down. I got the correct programming card and made sure both were programmed identically. What next....do I need new ESC's?

    Also, these are 120 amp. Running 3s so do I need 120 amps? I need them to be super low profile like these so I can have the deck/console sit in right.

  7. #7
    Join Date
    Jul 2016
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    IL
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    Do you have enough slack in the wiring to connect the port side motor to the starboard side ESC and vice versa? Perhaps it's not an ESC issue, but something motor related, or binding in one of the cables. See if the slow side continues to be slow or if the issue moves after the swap
    Vac-U-Tug Jr (13mph)

  8. #8
    Join Date
    Oct 2010
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    FL
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    I have swapped the motors already, I have swapped the throttle inputs on the RX already, I have swapped the batteries already. The stbd (right) ESC will not spool up as the port (left) does. . Plus the wiring you see in the hull is an older picture. Now all the wires going from the ESC's to the motors are brand new and are equal length. There is something with the ESC. For example, the side that runs hard when I connect the battery I get (BEEP BEEP BEEP) which would indicate to me 3s. But on the slower side I get one (BEEP) only. I think I have a bad ESC. Sucks because these aren't made anymore. Going to have to buy two brand new ESC's to get identical performance.

  9. #9
    Join Date
    Oct 2010
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    FL
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    Keeping in mind....I have the program card and they are both set to identical settings.

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