I'm building a small tracked robot. Currently it's just a Raspberry Pi, two motors and an L298N controller.
The problem I'm facing is that the motors are stalling at low voltages (which is what I assume the control controls). So it's impossible to move the robot slowly.
I don't have any kind of datasheet for the motors. I only know that the "recommended voltage is 3 - 9V" and they draw 300mA without load at 6V. They came as part of the kit I bought. The kit is no longer for sale, but here is an old sales page for it: https://www.botnroll.com/en/robots-educational-kits/1158-iron-man-4-tracked-chassis-for-arduino.html (note that this is not where I bought the robot and I don't know botnroll at all)
The motors are powered by a rechargeable 9V battery (Duracell NiMH 8.4V, 170mAh) which I had lying around and was the correct voltage.
The motors are controlled by a L298N module I got from AliExpress.
I've been trying to learn a bit about how these DC motors work (https://medium.com/luosrobotics/how-to-read-a-dc-motors-datasheet-f70fa440452b) and it looks like they need the highest current when stalled. So just before the robot begins to move, the motors need more current than when it is moving.
This leads me to believe that the problem is most likely the battery. The battery is not able to deliver the required current to overcome the stall. I haven't been able to find the max current for the battery. This is the only datasheet I have found: http://www.farnell.com/datasheets/2039764.pdf
Before going on a shopping spree, I'd like to ask you guys these questions:
- Is this conclusion correct and is the problem the battery?
- If yes, what battery solution would you suggest?
Here are some images if you are interested: https://photos.app.goo.gl/vT24qVB1xPFqTVScA