To fuse or not to fuse?

\Project fast car- broom vrrrr brooom

Void setup {
- motor driver rated 2amps connected to motor that may draw more than 2 amps at maximum stall;
//( stoopidly orded both without thinking)
}
Void loop{
If {

Question1 - what happens to driver if draw is over 2 amps

// I think it will be fried chicken at a vegan restaurant

If Else {
question2 - can I put a 2 amp fuse in to save the driver,

Else {
Question 3 - can I put in code to stop the stall?? Like something that reads the amp draw and stops before we are cooking.

Delay( waiting for knowledge drop) }

}

Little c++ joking around.

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Hi Josh.

At least you will learn from that mistake. Don’t forget that stall current would also be the start up current as the motor is stationary at that point. So you don’t have to “stall” to use that current.

Depends on how robust the driver is. Don’t forget start up, refer above.

Electronic bits tend to fail rapidly. A fuse takes a finite time (several mSec). It used to be thought that electronic bits protect fuses pretty well.

The driver may have settable current limiting. Worth checking. Externally measuring current could get pretty messy.
Even if you could it would have to be pretty quick and then you run the risk of preventing start up, read above.

Solution: learn from experience. Cut your losses and get a driver that will do the job. Allow about 50% “fudge factor”.
Stall current for your motor should be published. If not and this is a brushed motor it is pretty easy to estimate. If you don’t know how cry help and I will explain.
Cheers Bob

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Hay bob, thanks for helping,
??? Stall current = start up current???
The internet says otherwise. So I’ll need to do my own research on that.

You know what you know and you may be right but…. The AI interface is telling me something different.
:slightly_smiling_face:

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Go for it. You might plan to do your own research on the rest.
Cheers Bob

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No offence was intended bob, I’ll ask for advice but always check and do my own research before I do anything, anything else is just blindly following.

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Blind Freddy should be able to see that.
I did say I was referring to a brushed motor.
In both cases the motor is stationary and the only resistance to current flow is the actual winding resistance which could be less than 1Ω.
Irrespective what the internet says you can’t change that.
Be wary of You Tube. There is a lot of good stuff there but also a lot of pure garbage. Up to you to decide.

Start up current is also called inrush current and could be many times the running current.

Just what is this AI Interface??? Maybe it can fix the rest too.
Cheers Bob

Add on:
If you can find a motor driver with a “soft start” feature this will dramatically reduce any inrush current problems. Will do nothing for stall current however.
If your “motor driver” (don’t know exactly what it is yet) is some sort of speed controller/driver this may already be incorporated.

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Hi Josh,

You’re very likely to damage the motor controller if it rated to a max of 2A, although it may be worth checking if this is a continuous current rating or a peak rating ( for example our Makerverse driver is rated to 1.6A continuous and 2A max)

A fuse will help protect the driver, although if it blowing the fuse often then its probably better to upgrade drivers.

We have a range of Current Sensors that you could look at using, most of them are on the pricey side so it would probably be more economical to get a higher rated driver.

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Hay dan, is a Hall effect sensor that’s in the ESP32cam do the job??

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Hi Josh,

I would say the inbuilt hall sensor would not provide a very good reading of measuring the current.

I learnt from Bob and the net that a fuse is only good at protecting the power source, any damage to components downstream from a fuse would be seeing a fault that could happen much faster than a fuse can blow. i.e. over-voltage

A ramping speed function ought to help out here, but note that when the motor is still, and you ask it to move forward, it will be pulling almost (if not all) of its rated stall current.

Loved the C++ post style :laughing:

Thanks Liam. Why do you think the inbuilt sensor would not be good at measuring the current, isn’t that its job ? Just interesting in understanding. I don’t have any experience with it yet but will be doing some experiments.

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Hi Josh,

The magnetic field emitted from a single unwound wire does not emit as much as a magnet would, I have a feeling this onboard sensor might be useful for something like a reset button, where you don’t have to open the enclosure, or something along those lines.

If you want to monitor the current a motor is drawing, a dedicated external module would be most suitable (or if it is built into the motor driver): Current Sensor Carrier ACS724 | Buy in Australia | POLOLU-4041 | Pololu | Core Electronics

Happy to answer any other questions you have

Hi All
Still think it would be far easier and cleaner if you got a driver that will drive the motor. Or get a smaller motor but that might not be an option.

That way you accommodate the stall AND the inrush current.
Cheers Bob

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