Preventing 20A overcurrent to avoid blowing built-in battery fuse

Support Motor controllers/drivers and motors
1

im gonna preface by saying im pretty new to electronics, and im sorry for the yap

I have an Arduino Uno, which I want to use to control 4 37D 12 volt Metal Gearmotors for a robot, which have a stall current of 5.5A.(but could probably pull more in very short periods) Preferably, I’d like to use one of those 12V FTC batteries, but the problem is that they cannot handle currents over 20A because of their 20A fuse. The robot will normally draw safely under 20A(the fuse) and 16.5A for the matter(recommended maximum current draw for the motors). How do I prevent the spikes in current, such as when the robot hits a wall, from blowing the fuse?

Not sure if it will help much, but here’s the motor driver I’m planning to use. It has 2 channels, so 2 motors will be wired in parallel on each channel. However, while it states it has overcurrent protection, the datasheet is worded a little weirdly and I’m not sure if it protects against drawing 10A or if its protection is based on its temperature.

clarification: I’m not worried about the driver being able to handle the currents. I’m wondering how I should go about limiting the current draw so it never draws 20A during its peaks; and this is made under the assumption that there is no overcurrent protection on the motor driver.’

currently, this is my list of potential fixes:
capacitors
polyswitch fuses
custom overcurrent circuit(dont want to do, bad at electornics) / different motor driver

2

Hello.

You could try adding some method of detecting a stall (e.g. something like bump sensors). If you can detect it quickly enough, you might be able to prevent the fuse from blowing (fuses often take awhile to blow; if you have the specific part number you can try looking up the specs). Additionally, in practice, depending on the scale and design of your robot, it might be unlikely for multiple wheels to stall at once. In my experience, small robots will generally tend to spin their wheels in place (i.e. slip) instead of completely locking them up (and it is uncommon for all of the wheels to lock up at once).

Additionally, the current draw is proportional to the operating voltage, so to be extra careful you can limit the maximum duty cycle. For example, limiting the maximum duty cycle to 80% will effectively limit the stall torque to 4.4A.

Depending on your application, you might consider using some acceleration/deceleration limiting to prevent current spikes when starting up or switching directions rapidly.

Brandon

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