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9V DC Motor Stutter

Discussion in 'Sensors and Actuators' started by yagizgg, Oct 27, 2020.

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  1. yagizgg


    Oct 27, 2020
    Hello, a newbie here
    I salvaged a DC motor from a RC car and wanted to repurpose it by hot glueing it into a pipe and mounting a dust broom into its shaft. Motor runs fine on 9 volt battery but as most of the 9 volt batteries, its voltage starts to gradually drop after 10 seconds all the way to being unable to turn the motor. Tried running it with 4 batteries in parralel with 6 volts. Voltage doesnt drop but not as stong as I'd like it to be and there is not enough clearence to have 6 batteries let alone 4. So I went ahead and bought 9 volt 1 amp adapter to run it directly through the wall. Runs ideally when unmounted but when ı mount something on its shaft it turns fast for a second then comes to a complete halt and turns for what ı assume to be 10 degree, every second. If any Electric savy can help, I would be eternally grateful because it kind of became an honorary matter.
    Motor in question is labelled "RC-280SA"
    Thank you all in advance.
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    That is insufficient information as the motor comes with this label for several nominal voltages:
    • RC-280SA 2865 for 6 V
    • RC-280SA 2485 also 6 V
    • RC-280SA 20120 for 9 V
    Assuming your's is the 9 V version, then this motor draws 0.76 A at maximum efficiency but can draw up to 4.1 A when stalled (datasheet). I assume in your setup (mounted into the pipe with the broom attached the motor draws over 1 A. Can you verify/measure the current with an ammeter or multimeter? If I am right, then the power supply will be overloaded. It then will thermally overload (overheat) and shut down. After cooling a bit (that's where your 10 seconds come into play) the power supply restarts, the motor starts turning but as the starting current is also over 1 A, the power supply immediately shuts down again.

    I guess you'll need a way more powerful power supply, something that can output 9 V at 4 A or more (9 V/5 A would be a good choice).
    bertus likes this.
  3. yagizgg


    Oct 27, 2020
    I would like to clarify that 10 seconds thing was on 9 battery that when it starts to drop voltage until it recovers, motor runs indefinately on 9 volts unmounted. Actually full description on it refers itself as "RC-280SA 2675/DV" but just because it wasnt on their site and there are no datasheet about it anywhere I assumed it was a 9 volt one because the batteries that used to run RC car were 9.6V 650mAh. "Broom" is nothing more than 20 grams tops and compared to the actual weight of the toy car it should feel like couple of screws. Over the craze ı went ahead tried to stop the motor by friction of my fingers while it was running. Aaaaand it was quite powerful and hurt my fingers while trying so and actually failing to stop the motor. So ı thought it should be more than weight of the mount. I only have a pocket multimeter and only measures voltage. However ı have noticed the light flickering on the adapter so... yeah Im completely stuck at this point.
  4. Bluejets


    Oct 5, 2014
    Show a drawing of exactly how this is mounted.
    Motors such as you describe usually run at speed and bogging down will cause excessive current draw and can cook the motor windings.
    Also what is the 9v battery comprised of.
    9v 1A plug pack not suitable either for most applications.
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