Question Regarding DC 775 Motor Power Consumption

Thread Starter

Benjamin0904

Joined Oct 3, 2020
31
Hi everyone! I am recently debating if I should buy a DC 775 Motor for projects in the future. While I mainly researched its specification, I also faced some controversy which made me question its true specifications. I noted that a common 775 motor is 12-24 DCV. And of course, the RPM varies based upon that voltage. I am trying to find out how many amps the 775 motor draws at 12v. In this case I am measuring "no load" current. If I could just figure out the no load current of a 775 motor at 12v, that would be awesome. I just like to plan ahead before I buy stuff since I am a teen who does not want to waste money.
Thanks so much,
Benjamin
 

MisterBill2

Joined Jan 23, 2018
8,744
I am guessing that the "DC 775" motor is a motor of some kind with that part number. And please let us know what s "common 775 motor" is. That is not a usefully descriptive term.
The fact is that without doing some research on line, we know less about that motor than we do, and thus thee is no clue as to how much current it draws.
 

Thread Starter

Benjamin0904

Joined Oct 3, 2020
31
I am guessing that the "DC 775" motor is a motor of some kind with that part number. And please let us know what s "common 775 motor" is. That is not a usefully descriptive term.
The fact is that without doing some research on line, we know less about that motor than we do, and thus thee is no clue as to how much current it draws.
A 775 motor is a Direct Current motor, with the numbers representing part #. It is a small hobby motor that provides semi-strong torque and very fast speeds. Of course all this is just what I've read about. If it is helpful I will include two links on what I was confused about.
775 DC motor powered by GOPHERT CPS-6005 60V 5A variable power supply - Bing video
In the video above, the person experimenting finds out that at 12v, the motor will draw about 1 amp while in the amazon listing below, the minimum rated current is 4 amps. I'm just confused. That's all. I have no experience also with these.

775 DC Motor DC 12V - 24V Max 10000RPM - 20000RPM Ball Bearing Large Torque High Power Low Noise Gear Motor Electronic Component Motor 2pcs - - Amazon.com

Thanks.
 

Sensacell

Joined Jun 19, 2012
2,821
At 0 RPM, the current is limited by the (unknown) armature resistance, which is usually very low- expect the motor to draw many amps when starting. (10-20A?)

An unloaded DC motor has losses from bearing and commutator friction, this represents power loss.
The motor will draw a current that satisfies this loss factor while spinning near its theoretical top speed.
This current is hard to predict but can be easily measured.

The sellers of these motors are just middlemen, and usually have no real datasheets for the motors they sell.
You just have to buy it and test it yourself, OR buy from a motor company that has real datasheets for the products they sell.
 

MisterBill2

Joined Jan 23, 2018
8,744
I did follow the amazon link and saw the photos of that motor. What I see is a very cheaply built motor that has what I consider a fatal flaw. The terminals have a cross section reduction next to the motor body. That is a deal breaker for two reasons. First, it assures me thatthe terminal will break off after being beny just a very few times. The reduction is to reduce heat transfer during ssoldering because there is not enough material in the plastic part to avoid melting during soldering. It also means that the brush heat generated during running is poorly transfered out of the motor.
Also note that the section about warranty and support line is blank. So this motor is an unknown quantity. And the dimensions given are for the package, not for the product. So the product is rather over-priced, as I see it.
 

MisterBill2

Joined Jan 23, 2018
8,744
I suggest shopping elsewhere for a surplus motor. Maxon is a brand that will not only be a better quality, but will also be able to provide all of the information that you could possibly use about their products.
 
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