I've been making a line follower using two of those yellow 3-6V dc motors, a QTR-8RC Reflectance Sensor Array a L298N motor shield driver and a Arduino Nano, all powered with a 9V battery.
Thing is, after just like 2 minutes the robot starts to loose speed, and eventually it stops completely. (Might be because this motor shield driver only operates with voltage up to 5V). On the L298N datasheet we can see the motor driver operates with a current ranging from 0 to 36mA. However, the battery i'm using has 200mAh and can hold up to 2/4 hours before it starts losing Voltage at 50mA!!, as you can see on this graph. I think the problem here is the motor driver, and I've seen some alternatives such as the Adafruit DRV8871 DC Motor Driver or the Motor Driver - Dual TB6612FNG (1A). Can you tell me if the problem is really from the L298N motor driver, or if I am doing something wrong?