Need recommendation for Power Supply and Speed Control for 12v DC Motor

The power supply and controller look suitable. However, the comment that the controller needing added wire to handle over 5A does make me a little nervous. I hope that their instructions explicitly tell you which traces require the extra copper. One surprise you might have though is that some DC electric motors only spin in one direction. With this being a scooter motor drive, you might have an electric motor of this type. The controller also warns you that larger heat sinks will be required for heavier loads. I would consider adding material to the heat sinks to handle the larger heat dissipation instead of trying to replace them. Specifically, I would mount the heat sinks to the chassis of the box you should put all of these item into. But first, verify that the heat sinks are electrically neutral You will need to have the box vented for the supply has an integrated fan and probably your own added fan to exchange air would not be a bad idea.

Wait one minute, there is a link to the instruction manual. It says in the manual that even though the MOSFETs are capable of handling 30A, the driver circuitry limits the kit to no more than 10A.

Interesting, thanks for the advice! I will probably mount the power supply in a separate chassis, since the pottery wheel will get wet by design & I want to keep the AC components completely separate. I've actually considered just running it from a permanent battery, and connecting to a charger when not in use. Could be more safe that way.

Confirmed that the motor works in both directions by simply reversing the wires.

Could you recommend a source for a good speed control that would support 15+ amps? The bidirectional speed control device is nice but I can just wire in a reverse switch if necessary. I found a schematic for a speed control that says it will support 35 amps but it's been a long time since I tried to assemble a circuit board from a schematic...

PWB Schematic

I did a quick search at Digikey and found this TI motor drive module. It maybe more money and control than you want or need but my search did not take me long. For your safety, you might want to also consider a medical grade power supply.

Carl's also offers a DC Pulse Width Modulator that will handle 30ADC. A DPDT switch will reverse the direction of the motor without trying to find the null on a potentiometer. The PWM should be mouneted remotely to the motor assembly. The supplied heat sink should be sufficient for the application and a pancake fan can be added for additional coolin, if necessary. A medical grade power supply is not necessary if there is a low probability that you will come in contact with the HV side. For even greater safety, a remotely controlled contactor can be easily fabricated that will allow the operator to control the power supply with low voltage/low current while the contactor handles the HV/HI.

Yes it is true DC Motors run in both directions, but was the gear box off a scotter meant to run in both directions? The gear box in a scotter is usually meant with the bearings and gears to run in only one direction. You should check with the manufacture about this or you could run into possiable problems in the future.

Good Luck

Taz

It is my opinion that your project will work, but life expectancy of your motor will not be that great. 12 volts at ~15amps for a brush DC motor from a scooter is asking for you to be prepared with an extra couple of sets of brushes and a spare set of bearings.

No fiery meltdown, just a high maintenance project.

Grab yourself a high torque slow rpm motor. One such place you can get one is from an old electric garage roller door...and they come complete with controller too. If you go that way...use of a chain/pulley is a must to offset the motor from a watery environment.

Your design seems overly complicated. Run the scooter motor off a car battery. Reduce the speed with a pulley and belt set. Recharge the battery with a charger while not making pots. Series resistance in the circuit should reduce speed and power consumption. If a high degree of speed and or power consumption turns out to be needed for artistic or practical reasons adding a variable amount of series resistance to the battery-motor circuit should do the trick. I have not enjoyed very good reliability out of AC-DC power supply converters with heating and component failure as primary problems. At the power level you mention a dedicated household circuit would be needed - running anything else on the same line would greatly increase the likelihood of circuit breaking and component failures. A worm gear gear reduction would allow the motor to run wild while doing little work so the wheel was slow but very steady putting little load on the motor and so reducing the total draw of the machine. These are some fairly bullet proof alternatives you may wish to consider. Best wishes, Mr. Gee

You won't need a dedicated power line for a 12V 15A motor. With a switching supply working at a poor 75% efficiency that will mean a pottery wheel drive will run 12V*15A/.75=240 Watts. If you can run a hair dryer on your outlet, you can run this motor with an appropriate supply and motor drive.

Thanks everyone for the advice! A couple of things:

I realized I said scooter which isn't all that accurate. It's actually one of those assisted mobility devices for those who have trouble walking. So this motor has some serious torque & is designed for a load far above spinning a few dozen kilos of wet clay. The motor spins at about 70 RPM on 12V, and it has a differential gearbox of which I have clamped down one side to double the RPM of the wheel to 140, which is as fast as it needs to go.

I think the recommendation of using a battery full time, and charging it when not in use, is probably easiest. Also a DPDT switch to reverse direction. Simple, simple. I still have the question of speed control though, whether I add a variable resistor or a PWM control I just need it to not burn up under the expected load. I may have exaggerated it a bit, I was able to spike it up to 15A by practically sitting on it. Under no load (other than the wheel itself) it draws a steady 5A. With a pile of clay, once at full speed, I wouldn't expect it to draw more than 7 or 8A max (though I haven't tested it).

Thanks again for everybody's advice, you all are very nice people :)

you can make a resistive speed control for it from a few feet of the nicrome wire found inside common 110v hair blow driers,if you want to go cheap. Just hook it in line to the positive, and slide the lead to the motor back and forth over the length of nicrome wire to adjust the speed. More distance means less power to the motor, as the 2 leads get closer, the power will increase

Hi, I'll suggest an old/scrapped "throttle" from a cordless drill, typically 14,4 V to 18 V. It will alow you to reverse and set speed linearly almost from zero RPM to full speed. Both directions. I have measured a Bosch cordless drill using 10 A, 14 V during load at half speed and the throttle not getting too hot. To maintain a certain speed, mount the throttle and place an adjustment bolt where your finger is supposed to be.

best regards, moe