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Solar Attic Fan Stepper Motor Power Supply

Former Member

I'm looking to power a solar attic fan when the sun is not shining on the solar panel.  The specifications of the solar panel are as follows:

 

Polycrystalline solarpanel

Max Power: 30W

Max Voltage: 24V

Max Current: 1.25A

Open Circuit Voltage: 28.8V

Short Circuit Current: 1.42A

 

I purchased an AC/DC power adapter (wall wart) with the following details:

 

AC/DC Adapter

Switching Power Supply

Model DSA-0151A-12S

Input AC 100-240V 50/60Hz

Output DC +24V 1A

 

However, when I connect the power supply directly to the fan stepper motor, I am only measuring 0.01A and the fan spins for a second then stops for a second and on and on...  I'm not certain if I need a linear power supply as opposed to a switching power supply.

 

Thoughts?

Parents

  • Hi Mark, Are you sure that you have the right polarity on your connection between the adapter and the fan motor? Try switching the wires around for a couple seconds to see if the motor starts up. Also if you really have a "stepper" motor this is not the right way to power it. I suspect that you have a regular DC motor if it is designed to run on the solar cells as an attic fan. It is also possible that you have a defective power supply. Do you have a meter so you can measure the voltage when you hook up the fan. If the voltage is fluctuating as the fan starts and stops you may be triggering an over current protection in the power supply. Most DC motors will draw extra current until they get up to speed. You could try temporarily buffering the motor start up current with a one or two ohm resistor in  series with the motor. This would limit the current stress on the power supply and perhaps it would not trigger the protection circuit. Do not leave the resistor in the circuit other than for the test unless it has enough wattage as it may get hot.

    John

Reply

  • Hi Mark, Are you sure that you have the right polarity on your connection between the adapter and the fan motor? Try switching the wires around for a couple seconds to see if the motor starts up. Also if you really have a "stepper" motor this is not the right way to power it. I suspect that you have a regular DC motor if it is designed to run on the solar cells as an attic fan. It is also possible that you have a defective power supply. Do you have a meter so you can measure the voltage when you hook up the fan. If the voltage is fluctuating as the fan starts and stops you may be triggering an over current protection in the power supply. Most DC motors will draw extra current until they get up to speed. You could try temporarily buffering the motor start up current with a one or two ohm resistor in  series with the motor. This would limit the current stress on the power supply and perhaps it would not trigger the protection circuit. Do not leave the resistor in the circuit other than for the test unless it has enough wattage as it may get hot.

    John

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