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I am making a line follower robot. The issue is trying to make the motors run.

The L239D module has 4 inputs pins (to control two motors), 4 output pins (to drive motors), and 6 power pins (5V, 5V, GND, GND, 9/12V, and 9/12V). I have used one 5V pin to connect it to an Arduino's 5V supply and one of the 9/12V pins to two 9V batteries in series.

The motors are barely running and when the robot is on the ground it is not able to move. I even tried three 9V batteries in series to get the voltage up to 27V but it doesn't help.

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  • Is your motor being drived when you hold it in the means when it is not placed on the ground
    – Maaz Sk
    Oct 21, 2020 at 5:06
  • yes , when it is in hand i do see it getting rotated but not on ground Oct 21, 2020 at 6:24

3 Answers 3

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9V batteries, assuming you mean the little PP3-size ones, can't supply the current needed for driving robot motors; they are intended for low-current applications.

Putting them in series will give you a higher voltage, not more current, and the higher voltage could damage something else in the circuit.

Assuming you connected everything correctly, including ground: you need bigger batteries. Even 6 AAs in series would be much better than using a 9V battery for getting your robot to move.

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  • If i can connect 3 9V batteries in parallel, is that going to help! , as the current is the requirement. Oct 21, 2020 at 4:39
  • Have you tried batteries in parallel
    – Maaz Sk
    Oct 21, 2020 at 6:28
  • It will help a little, but they will be empty very quickly. Make sure they are at about the same voltage before connecting them in parallel.
    – ocrdu
    Oct 21, 2020 at 9:21
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On your next try use a different H-Bridge, one with MOSFET outputs, you can have a voltage drop across the L239D of 2.4V. Measure the voltage at the motor and at your batteries you will see what I am getting at. You might want to try connecting the motors directly to the battery first to see if it will do what you want.

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I guess using 9 Volt battery in parallel will do your work because if the motor is moving as you quoted above means it is getting the voltage but not enough current to drive it, please connect the 9 volt battery in parallel and it will work for you

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