user68928: I am trying to build a robot using a kit I got from amazon:
https://www.amazon.co.uk/DFRobot-Tank-Mobile-Platform/dp/B014L1CF1K?th=1
(it uses plastic motors).
The main problem that I am having is that whenever I try to apply a battery with 9 volts to one of the motors it only moves the slightest amount. I am not sure if the voltage is too low or not because in the manual it is using 7.4 volts.
The motors are connected up to a motor driver, here is a diagram of what it looks like

Could the motors potentially be broken? (Hope not because it means I will have to dissect the whole robot)
The motors I am using look like this:


user313: 9v batteries are incapable of supplying enough current for a motor; their best application is tiny-current, standby devices like smoke detectors. You need a power supply that can deliver much more current than the 9v brick can. 6 AA cells in series would do much better. 6 pairs of AA-cells would give you longer run time (each 2 cells in parallel; the 6 parallel pairs in series). You could accomplish the same thing using AAA-cells if your project values space over run-time.

68928: <p>I am trying to build a robot using a kit I got from amazon:
<a href="https://www.amazon.co.uk/DFRobot-Tank-Mobile-Platform/dp/B014L1CF1K?th=1" rel="nofollow noreferrer">https://www.amazon.co.uk/DFRobot-Tank-Mobile-Platform/dp/B014L1CF1K?th=1</a>
(it uses plastic motors).</p>
<p>The main problem that I am having is that whenever I try to apply a battery with 9 volts to one of the motors it only moves the slightest amount. I am not sure if the voltage is too low or not because in the manual it is using 7.4 volts.</p>
<p>The motors are connected up to a motor driver, here is a diagram of what it looks like</p>
<p><a href="https://i.stack.imgur.com/D5mF5.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/D5mF5.png" alt="enter image description here" /></a></p>
<p>Could the motors potentially be broken? (Hope not because it means I will have to dissect the whole robot)</p>
<p>The motors I am using look like this:
<a href="https://i.stack.imgur.com/56ITo.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/56ITo.png" alt="enter image description here" /></a></p>
 313: <p>9v batteries are incapable of supplying enough current for a motor; their best application is tiny-current, standby devices like smoke detectors. You need a power supply that can deliver much more current than the 9v brick can. 6 AA cells in series would do much better. 6 pairs of AA-cells would give you longer run time (each 2 cells in parallel; the 6 parallel pairs in series). You could accomplish the same thing using AAA-cells if your project values space over run-time.</p>
