Posted by Amy .
Student on team #126, Gael Force, from Clinton High and NYPRO.
Posted on 7/5/2000 2:45 PM MST
Does anyone know how many RPMs a Fisher-Price motor spins at, either with or without the gearbox? If you have any idea, please post it or e-mail me. Thanks 
Posted by Joe Johnson.   [PICTURE: SAME | NEW | HELP]
Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.
Posted on 7/5/2000 6:51 PM MST
In Reply to: How Many RPM does a Fisher-Price Motor Spin At? posted by Amy on 7/5/2000 2:45 PM MST:
The Mabuchi motor not attached to the gearbox has a free speed of 15,000 RPM at 12 Volts.
This info as well as lots of other motor info is in spread sheet from a presentation on FIRST motors that I gave at Philly last year. The presention & spreadsheet are available if you wish.
Go to the ‘white papers’ section of this web site or click on the attached link.
Posted by Adam Krajewski.
Student on team #68, Truck Town Terror, from Walled Lake Central High School and General Motors Truck Group.
Posted on 7/5/2000 9:01 PM MST
In Reply to: 15,000RPM Free Speed posted by Joe Johnson on 7/5/2000 6:51 PM MST:
Are you sure? :
We tested one, and found it to be 16,000 RPM @ 12 volts. I didn’t do the testing myself, but I’m sure that was our results. I’ll try and get ahold of the guilty parties, to see how they tested it, whether with a dynometer (which I believe they used) or some sort of calculation.
Adam
Posted by Adam Krajewski.
Student on team #68, Truck Town Terror, from Walled Lake Central High School and General Motors Truck Group.
Posted on 7/5/2000 9:24 PM MST
In Reply to: Re: 15,000RPM Free Speed posted by Adam Krajewski on 7/5/2000 9:01 PM MST:
Now that I look at the ‘16,000’, I think I’m wrong…
Hehe.
I have learned a valuble leason… Don’t question Dr. Joe.
Adam
Posted by Joe Johnson.   [PICTURE: SAME | NEW | HELP]
Engineer on team #47, Chief Delphi, from Pontiac Central High School and Delphi Automotive Systems.
Posted on 7/6/2000 5:58 AM MST
In Reply to: Re: 15,000RPM Free Speed posted by Adam Krajewski on 7/5/2000 9:24 PM MST:
It is entirely possible that the motors have a free speed of 16,000 at 12 volts.
The only thing I am basing my number on is a print from Mabuchi (they are a significant supplier to Delphi, so I have folks to ask for such things).
Anyway, the print says 15,000 rpm free speed, but that doesn’t mean that every single motor will run exactly at that nominal value. I would not be surprised to learn that the motors vary up and down 10% which would mean that the 15,000 rpm could be as low as 13,000 rpm and as high as 16,500 rpm.
Joe J.
Posted by Michael Betts.
Engineer on team #177, Bobcat Robotics, from South Windsor High School and International Fuel Cells.
Posted on 7/6/2000 6:55 AM MST
In Reply to: Print says 15,000 – Actual motors may vary… posted by Joe Johnson on 7/6/2000 5:58 AM MST:
In addition to Dr. J’s comments, the speed will also be affected greatly by the battery supply voltage. If using a fresh, fully charged battery, a voltage of over 13 VDC would not be uncommon. Likewise, after a match or two and under ‘competition’ loading, the battery voltage can easily dip to under 11 VDC. This variation in supply voltage will definately affect motor performance.
‘… your RPM may vary.’
Mike
Posted by Adam Krajewski.
Student on team #68, Truck Town Terror, from Walled Lake Central High School and General Motors Truck Group.
Posted on 7/6/2000 2:56 PM MST
In Reply to: Re: Print says 15,000 – Actual motors may vary… posted by Michael Betts on 7/6/2000 6:55 AM MST:
16,000 rpms @ 12 volts, brand new, never been used. Our test was done on some kind of laser-rpm-finder-thingy that is suppose to be extremely accurate.
I told them the first time they tested that they should have tested at 13 VDC, to see the difference…
We should probably test more than one motor, also, to see a difference between motors.
Adam
Posted by Adam Krajewski.
Student on team #68, Truck Town Terror, from Walled Lake Central High School and General Motors Truck Group.
Posted on 7/6/2000 2:57 PM MST
In Reply to: Re: Print says 15,000 – Actual motors may vary… posted by Michael Betts on 7/6/2000 6:55 AM MST:
16,000 rpms @ 12 volts, brand new, never been used. Our test was done on some kind of laser-rpm-finder-thingy that is suppose to be extremely accurate.
I told them the first time they tested that they should have tested at 13 VDC, to see the difference…
We should probably test more than one motor, also, to see a difference between motors.
Adam