12 Volts Pumped Thru Motor!
Well, I'm working on my multi-cell Dragster, and I'm wondering how much juice one of these motors will take.
So.... I made a motor test stand out of a KIT Racing chassis, grab a couple KIT 2.2 and 2.6 motors for cannon fodder, and my variable voltage A/C adaptor for power. The adaptor has voltages of 1.5v, 3v, 4.5v, 6v, 7.5v, 9v, and 12v, all @ 300mA. Please keep in mind that my testing was ultra seat-of-the-pants, so I don't have any graphs or anything.
After breaking in the motors at 1.5v for 2 minutes each, I start to crank up the juice! I ran the motors for 10-15 seconds at each voltage setting, with a 30 second "cool-down" period between "pulls".
The results are as follows; Both 2.2 & 2.6 motors ran at all voltages up to 12v! There didn't seem to be much difference in the motor whine/pinch beween 7.5v to 12v. Torque didn't seem to differ much either at higher voltage (I had gear/axle sets connected- I checked this by lightly applying pressure to the wheel with my finger). I also monitored the heat by keeping my finger on the heat sink constantly (they all got warm at high volts, but at no time did any get too hot to the touch).
The motors all failed by the time I got to the end of 15 seconds on the 12 volt setting (They all ran in the end, but very very slowly).
But the autopsies of the dead motors were surprising. I was expecting to see burnt and fried armatures & brushes, but instead found that the motors didn't suffer ELECTRICAL failure; they ALL suffered ENDBELL failure. That is, the holes in the endbells for the armature shafts were all melted and went oblong from the heat of the spinning armature shafts. The armatures and brushes/wipers all looked ok. Obviously a bushing or bearing would remedy this type of failure.
In conclusion, these motors will run, for short periods of time, at higher voltages. They could be used as-is for short-burst Drag Racing, or for even longer periods if the endbell had a bushing or bearing installed.
I hope you find this interesting. This means that with a transistor mod (to limit the voltage that goes to the PCB), we CAN send as much as 12 volts to these tiny motors!!!
John
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"It takes a Mopar to catch a Mopar!" - Vanishing Point
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