I need help with the up/down motor which is getting too much voltage and current. When I press the button to lower the claw, I measure a max of 73 dc volts and approx. 8.5 amps. The old motor says it can take a max of 65 volts, but it doesn't say anything about a max current. The old motor was seized and burned up but I got it working again but it's not a 100% working. I do have a new motor for it but I don't want to install it until I know I have the correct voltage and current. I was thinking of installing a 1 ohm 75 watt resistor to bring down the voltage and current to a max of 65 volts. Does anyone have any experience with dc motors?

Thanks,
Steve

 

Does the motor list wattage? That would give an indication of expected amperage. (amps = watts / volts)

I'm certainly not the expert you seek, but I will say that I'd be careful with a 75 watt resistor on what appears to be a 620 watt circuit right now (73 volts x 8.5 amps = 620 watts.)

You can take my calculations with a grain of salt, because inductive loads do a lot of things that seem weird to me, and that I clearly don't understand. Nevertheless, I don't think the numbers add up the way you want them to so far. Hopefully someone else can step in and clear things up!

 

I checked both motors again and I didn't find any listing about wattage. I connected the old motor tonight and it got very hot, really untouchable, and smoking a bit so I think I fried it. I will check it again tomorrow, but it seems to me that the current is what is killing the motor instead of the voltage, but I'm not sure about that. I know I need to reduce the voltage to 65 dc volts, but I'm really concerned about lowering the current too, but I don't know by how much. Right now, the claw isn't working properly because of the motor, but the way it's supposed to work is by pressing the button, the claw drops onto a stuffed animal and then the claw closes and hopefully lifts the stuffed animal up and the crane returns to the home position and drops the animal into the hole for retrieval. It appears that for a short period of time, maybe 10 seconds, after the button is pressed, the voltage and current may be at the max but I don't understand how that short time frame might burn-out the motor.