Arduino Ardumoto

I have a Ardumoto connected to the Arduino, which gets its power from a 9V 2amp power supply. I am wondering, how much power is available to me on the motor outputs? I am asking this cause i got lots of motors lying around non of them can be controlled seems they need to much power.

Well, according to what I am reading, you should be able to get around 2 amps @ 9V; what are the specs for the motors (have you been able to find this out)?

Something to keep in mind is that for any given motor, the startup current will generally be a lot higher than the running current; maybe the motors you have are rated at a certain amperage (running current), but the controller attempts to start them and the starting current is way higher than 2 amps, and causes some kind of protection to trip in the L298?

Another thing to consider is whether you will need a heatsink for the L298 in order to get 2 amps out of it; the multiwatt pin version has a metal tab for a heatsink, but the SO20 version may have to have such a heatsink bonded on the top (like with ArticSilver or such heatsink glue). Even so, it should at least start a motor and get it running, before it overheats (and trips its overheat mode).

Try hooking up some small hobby motors (3-6 VDC can motors) to it (also, note that the motors have to be brushed motors, not brushless). If the motors you are trying to run are ones from hobby RC cars or planes (and are brushed), they are likely too large for this controller.

Good luck! :slight_smile:

Thank you for the answer, unfortunately motors don't have make and model and shop i bought them has no idea about their power requirements. Small motors work just fine, but as i try to connect bigger motors that causes problems.

So just to make sure i am on the correct page,

if I have 9v 2amp power supply ardumoto provides 9v 2amp to the motors.

correct me if i am wrong here, but ardumoto gets its power for the motors from the vin pin no? and vin pin provides power directly from the power supply?

So if i test the motors before buying them with 9v 2amps and they work, i should be able to control them just fine from the ardumoto controller.

if I have 9v 2amp power supply ardumoto provides 9v 2amp to the motors.

Nope: at 2A, an L298 will lose about 4V across its drive transistors. And, without heatsinking, it won't provide a continuous 2A for long before going into thermal shutdown.

Description page for ardumoto says it supports 2 amp per channel doesn't that mean it should be fine upto 4 amps, or am i wrong?

doesn't that mean it should be fine upto 4 amps

Alas, no: it's not that simple.

There are lots of cases where a chip with n outputs can't source/sink n times the "per channel max". Like the ATMega in the Arduino, itself, which is rated at 40mA per I/O pin, but only 200mA for the whole chip.

But the real problem here is heat: the L298 has bipolar Darlington output transistors. If you drive a 2A motor with it, you have to extract and dissipate about 8W of heat from it. And that board ain't gonna do that. Not on a continuous basis: if the motor is being run at a relatively low duty cycle, so the average power dissipation is low, it should be okay. But it won't take a lot (a matter of seconds) of continuous 2A operation for the chip to overheat and shut down.