Choosing a Robot Drive Motor

[cosmonavt]

Yeah, and how can the cost be just 0.5$?

Well, as goes for **broken link removed** motor, I contacted the supplier again and he says the amperage is 1A.The torque mentioned is 0.95kgcm. Should I stick to this one? Its branded too, by Wenzhou Zhengke. The specs seem more reliable also.

Would 60RPM be good enough to drive my robot at a good pace? That's what I would doubt.

 

[misterT]

Yeah, and how can the cost be just 0.5$?

Well, as goes for **broken link removed** motor, I contacted the supplier again and he says the amperage is 1A.The torque mentioned is 0.95kgcm. Should I stick to this one? Its branded too, by Wenzhou Zhengke. The specs seem more reliable also.

Would 60RPM be good enough to drive my robot at a good pace? That's what I would doubt.

1 A sounds suspicious because the specs for that model say ~200mA. Maybe it can take 1 A for a short period of time. For all the choices though, I think you could give this one a try. It is not a bad motor and you have better specs available for this motor. It is worth the 10$ anyway.

You probably can drive it with higher voltage to get more speed.. maybe 15V, and briefly with higher current to get more torque. Just don't do it continuously and be careful not to overdrive the motor if it is stalled.

 

[cosmonavt]

Hey I just realized, even if its 60RPM, then at max RPM, the speed will be 1Rotation per second. 1 rotation on a 10cm dia wheel is 2 pi r = 2 * 5 * 3.41 = 31.4 cm per second.

Isn't that a decent speed, for a robot? And yes, the supplier seems confused. Last time i asked, he said 0.16A, maybe. Now he says 1A. But as per the calculations we did earlier, ~0.2A is sufficient. Perhaps I should stay with this one. Thanks man!

 

[misterT]

Hey I just realized, even if its 60RPM, then at max RPM, the speed will be 1Rotation per second. 1 rotation on a 10cm dia wheel is 2 pi r = 2 * 5 * 3.41 = 31.4 cm per second.
Isn't that a decent speed, for a robot?

You calculation is correct. If you use the robot indoors 30 cm/s is a very decent speed. Outside it might feel slow. If you plan to make a smart robot, then you will be going slow most of the time

 

[cosmonavt]

Can you tell me where did you look up the specs and what is the exact model of this motor? I searched all the page but ZGA25RP is the max I find. ZGA25RP is a whole range of motors. ....

 

[misterT]

Can you tell me where did you look up the specs and what is the exact model of this motor? I searched all the page but ZGA25RP is the max I find. ZGA25RP is a whole range of motors. ....

I googled and also found lots of different specs. This one looked the most reliable: https://www.electro-tech-online.com/custompdfs/2011/12/DC20Gear20Motor-ZGA25RP.pdf
I assumed that the exact model is ZGA25RP-1256-71, because that fits the "60 RPM" specification.

 

[cosmonavt]

How goes this motor: ZGA25RP27.5i-5600 on **broken link removed**?

It says 12V200. 200 RPM probably? I have tried everything but I have failed to find the torque and amperage of this motor. Can you help me with this?

And the cost is (I think) 29 yuan which makes it around 4 dollars.

 

[cr0sh]

Current is not pushed, current is pulled or drawn.

If the motor is rated at 160 mA stall current, and the h-bridge or driver can supply up to 227 mA of current, that leaves a margin of current supply of about 42% (if my math is correct), which should be adequate. If the current pulled by the motor somehow exceeded that of the driver (here at 227 mA), you would smoke the driver; but, if given that the motor really has a stall current of 160 mA, you won't exceed the current delivery capability of the driver (now then, the driver may warm up, or possibly overheat, and hopefully it will have a automatic shutdown to keep that from happening; if not, you will need to find some way to deal with that extra heat to keep the driver cool).

Regarding your question on chinese toys - it's called economies of scale (that, and bad or misleading labeling, I would imagine)...