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Motor Tips 

Click here to read about the AmpFlow A28150 and A28400. Powerful custom motors designed for BattleBots.
BioHazard '96 to '99 used two permanent magnet DC motors that I ordered from a surplus dealer. BioHazard 20002003 uses the A28400 AmpFlow.
Motor Facts and FAQs:
To get an estimate of your motor's horsepower, you need to know just one fact: the current draw when stalled. Here is the formula: For a heavyweight robot, (220 pounds), shoot for 1.5 horsepower per motor minimum, 2.5 horsepower for a fast robot.
If you double the voltage, you also double the current that the motor can draw. If your battery can put out that much current, and your electronics can handle it, you will get four times the horsepower by doubling the voltage. The RPM of the motor will also be doubled and the motor will get four times as hot, (heating is proportional to current squared).
If you wire two motors in parallel they will each be able to deliver their full power, so if your battery can put out that much current, you will get twice the horsepower. If you wire them in series, you double the resistance that the current has to pass through, so you will only have 1/2 of the current, and 1/2 of the power. Putting two motors in series gives you only 1/2 of the power of one motor alone.
To change the timing of a motor you should rotate the brushes relative to the magnets.
On some motors this is easy to do, but if the brush holders and the magnets are mounted on
the same part of the motor housing, then you will have a much bigger job to alter the
timing.
Yes, you can rewind motors to increase either torque or RPM (but not both). I have
rewound motors myself, but I don't recommend that you do it yourself unless you have a lot
of patience. To get more horsepower you should use fewer turns of a larger gauge wire. This will reduce the terminal resistance of the motor, and increase the RPM. The motor will develop more horsepower, but it will be at a less manageable RPM. In either case, you run the risk of damaging the magnets. With more turns, it is possible to generate higher magnetic fields that can demagnetize the magnets. With fewer turns, the motor will draw more current, which means it will run hotter, and that can also demagnetize the magnets. The damaging magnetic fields will probably be reduced with fewer turns, but if the current gets high enough, they might be the same or even stronger. This is the same type of problem that can happen if you pump more voltage into a motor than that for which it was designed.
That is an easy question! Check out AmpFlow.


