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# Current Consumtion by a DC Motor?

I am asking few questions EV related, more current related.

Let a consider a dc motor rated 4hp at 24v and 2hp at 12v.

So is there a way to calculate ampere draw of the motor at various loads.(like no load, full load, or any load).

And if we know the full load current of the dc motor then can we calculate the max load for the dc motor.

Next as the dc motor is 2hp at 12v then will this value be constant or will the motor be able to produce 4hp at 12v even rather than at 24v.

And will a battery eg 50ah be able to supply more then 50amp.

## Comments

5 years ago

i want to know dc motor current calculation formula with exampl..... any one help me......?

6 years ago

I WANT TO KNOW FULL LOAD CURRENT OF 111KW DC MOTOR

Reply 6 years ago

Unknowable. What is the operating voltage ?

6 years ago

I WANT TO KNOW FULL LOAD CURRENT OF 111KW DC MOTOR

6 years ago

I WANT TO KNOW FULL LOAD CURRENT OF 111KW DC MOTOR

7 years ago

4 horse power is 2983 Watt (3kW), http://www.wolframalpha.com/input/?i=4+horse+power+to+watt

Power (in Watt) is voltage(volts) times current (ampere), so 4hp at 24v gives 124,3A

http://www.wolframalpha.com/input/?i=4+horse+power+at+24+volt

This is a massive amount of current! Be carefull!

I don't know how the motor works with different loads, but this will be the maximum current draw with load I guess.

Also, I thought blocked DC motors could damage the motor somehow?

Reply 7 years ago

DC motors also have a stalled/blocked current rating.

Your calculation makes no allowance for efficiency, but it will be quite high, for a quality motor.

Also, the rated output of the motor occurs at some rated speed, since at zero speed, although its consuming a lot of energy, its not delivering any power.

7 years ago

Motors are loaded by applying torques to them. Power is supplied at a rate determined by the torque and shaft speed.

Motors are specified by consulting graphs of performance.

7 years ago

You may wish to read the Wikipedia article, which discusses the relationship between voltage, current and power, including load vs. noload conditions.