# Why is the Torque of the BM1418ZXF 1000W Motor So Low? I Need Help!

#### ldclaros

##### 1 µW
Hi everyone,

I'm working on a project with the BM1418ZXF 1000W 48V BLDC motor and I'm concerned about the torque specification. According to the datasheet, the nominal torque is only 3.5 Nm before reduction and 21 Nm after the reduction (1:6). However, I've seen many videos and testimonials where these motors move heavy loads without any issues. This motor is specifically known for its ability to move heavy loads in applications like rickshaws and cargo tricycles.

Even with an external gear ratio of 14 teeth on the motor and 38 teeth on the rear wheel that comes included in the kit, it doesn't seem to have enough torque to move 800 kg as the manufacturer indicates. But I've seen videos where it moves 500 kg without a problem. None of the mathematical calculations match the reality.

Can someone explain this discrepancy? Is there something I'm not considering?

I appreciate any help or explanations you can offer! I need this information for performing mathematical calculations for my design.

Thanks.

Assuming chain drive, decent bearings, and flat terrain, there shouldn't be significant loss. Yes the rated torque at that speed is low, but typical motor drives would be set up to produce many times that at stall.

Even at the rated torque, through the reductions that's like 57Nm at the wheel, which assuming a 20-inch wheel would be over 200N, which could accelerate 800kg at nearly 1kph/s.

You can move pretty much any weight as long as you've got the right gearing.
Where's this pulling demo, was it at a few mph?

800kg is getting close to the weight of a small car. That's a lot to ask of a 1.25 horsepower motor.

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48V x 26A is nominally 1248W electrical, 936W output at its optimally efficient load and speed according to the efficiency spec. Normally, that would be an e-bike rated 500W or maybe 750W. Anyway it's going to be an underperformer by "1000W" e-bike standards. Because of the ability to gear reduce the motor's output, you can use that much power to haul however much weight you want... as long as you do it as slowly as necessary.

I think it would be a better idea to use a Cyclone 2-4kW or 6kW gearmotor and a 50A or 60A controller if you want a real tugboat. That motor looks very much like a no-account clone of the real thing. They must have gotten stingy with the copper for it to be so derated.

They must have gotten stingy with the copper....
No surprise. The market price for copper lately has been climbing like a homesick angel - 'tis well past \$5/lb (the highest ever), and still rising.

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