I have a motor, but i dont know its wattage.
How to detetc its wattage then?

When i connect it with a dc source (12v 18A), it's start burning.

 

Is there any writing on the motor at all?
What size is the motor?

 

When i connect it with a dc source (12v 18A), it's start burning.

It looks rather grotty. If it's been salvaged from something it may have an internal fault which is causing it to draw excess current.

 

Does it run on 5V, can you spin the rotor by hand?

 

Are you guessing at 12v?
Check the generated output, if any when back feeding the shaft at a known rpm, 200 to 1krpm.
Max.

 

How did you determine to apply 12 VDC? I have seen motors similar which run on 1.5 volts up to 12.0 volts. If you over voltage a small DC motor then it will draw excessive current. That said 18 Amps as you posted is a high current and would require a heavy wire gauge to supply it. It would also require a pretty beefy DC supply source. I also agree the motor appears very dirty and who knows how old it is.

Ron

 

Most motors will take over voltage without any increase current as long as the BEMF is developed, the current will be the same, I have proved it with empirical testing, the danger is over speeding causing mechanical damage due to forces developed.
Max.

 

Is there any writing on the motor at all?
What size is the motor?

No printing outside of motor. It's old motor, probably printing wiped.

 

Does it run on 5V, can you spin the rotor by hand?

Its not running on 5v or 6v. I have a 12v battery but the motor rotate very slowly(almost rotate by hand). I've measured current of this battery, its called very low amp (0.5**).

 

How did you determine to apply 12 VDC? I have seen motors similar which run on 1.5 volts up to 12.0 volts. If you over voltage a small DC motor then it will draw excessive current. That said 18 Amps as you posted is a high current and would require a heavy wire gauge to supply it. It would also require a pretty beefy DC supply source. I also agree the motor appears very dirty and who knows how old it is.

Ron

It runs on 12v battery very little, because current of this battery is very low. So, i decided the motor could be high wattage.

 

Its not running on 5v or 6v. I have a 12v battery but the motor rotate very slowly(almost rotate by hand). I've measured current of this battery, its called very low amp (0.5**).

I think you caused confusion when you mentioned 18a in the OP.
Try rotating it as in post #5, and measure the rpm and the generated DC voltage from the motor, extrapolate from that the voltage that would be required for 2000rpm.
Max.

 

I think you caused confusion when you mentioned 18a in the OP.
Try rotating it as in post #5, and measure the rpm and the generated DC voltage from the motor, extrapolate from that the voltage that would be required for 2000rpm.
Max.

You mean rotate by hand and measure its voltage.

 

You need faster and steadier than by hand, monitor both rpm and voltage, at least 200rpm if possible.
Max.