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I have a 12v, 0.9A dc motor. Currently I have two 12v dc supplies which I borrowed from my friend. The current of the 2 dc supplies is 1.0A and 0.5A respectively. Is it safe for me to use the higher current supply from 12v dc supply (1A) or a 0.5A 12 dc supply to my dc motor?

Morgoth
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user39706
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  • While this question is partially about choosing a supply, its mainly about using a supply good for a motor, which has more concerns that are not answered by that duplicate. – Passerby Apr 05 '14 at 14:45

2 Answers2

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No. Neither is good for a 0.9A motor. Keep in mind, not only is the inrush current a concern, you also need to worry about stalll current. A motor under load can require more current, while a stalled motor could take up to twice the rated current, as arule of thumb. You want a supply that's at least 1.5x to 2x the stated current. So 1.5 to 2 Amp supply. Otherwise you risk damaging the supply.

Passerby
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The current rating on a power supply is the maximum current it is designed to provide, at its given voltage rating. In general, as long as the voltage rating is correct, you want a current rating that is at least as high as you need. Unlike voltage, it won't hurt to go bigger.

One example is your household wiring. Even though a typical wall outlet is able to provide 15 amps, you can plug in a 60W bulb (0.5 Amp) without a problem.

In the specific case, some types of motors have an initial current draw that is much higher than their rated current. I would use the higher-capacity supply, and hope it can handle the inrush current.

Good luck :)

bitsmack
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  • Thanks for the advised.This mean that 1A dc supply is better to overcome the inrush current right?If i connect with a 0.5A will it harm the motor or the power supply? – user39706 Apr 05 '14 at 06:43
  • You're welcome! And you're correct about the two supplies. Some power supplies have protection against overcurrent, and will just shut off. But, if it keeps underpowering the motor, either the motor or the supply could be damaged. – bitsmack Apr 05 '14 at 07:35
  • If you use the 0.5 amp power supply for the 0.9 amp motor, the power supply will be overloaded and its voltage may drop, it may just shut down, or it may blow a fuse. If the power supply has no internal protection, it will likely overheat, and may be damaged by that heating. – Peter Bennett Apr 05 '14 at 15:58