Troubleshooting Power Issues

Hi, this is my first post, so I apologize in advance if I don't get it right.

I have an Arduino Mega connected to an L298N motor controller controlling 4 motors, two on one side and two on the other. When I hook it up to the bench power supply, everything works as expected. When I hook it up to a battery case with 2 18650 Li-ion batteries, it does nothing.

Things I have verified:
I don't think it is a coding issue because it works fine with the bench power supply.
I tested the voltage of the battery pack and it is 7.9. I set the voltage in the bench power supply to 7.9.
When I connect the battery pack, the motor controller light turns on, so I know it is supplying power.
The total amps it pulls when the bench power supply is connected (and it is working) is 0.26 when one side of wheels is running and 0.41 when all 4 wheels are running.
The total amps it pulls when the battery pack is connected is
I bought another battery case and new 18650 batteries and tested that they were fully charged and it gave the same results.

Here is a photo in case it is useful.

Please advise on where to go from here with trouble shooting. I am at a loss as to what to do next. Thanks.

I hate power connections using multiple alligator clips. They're about the least reliable connector in the world. Try some more solid connection to the battery. Your picture shows battery +ve waving about in mid air so that's not much use.

Where are you measuring your 7.9V? It should be at the input on the L298 board. Is the USB still connected when you're using the battery?


Show us a good schematic of your circuit.

In the Arduino IDE, use Ctrl T or CMD T to format your code then copy the complete sketch.

Use the </> icon from the ‘reply menu’ to attach the copied sketch.

@casualtinkerer, your topic has been moved to a more suitable location on the forum.

This photo is of the motor controller being powered by the bench power supply, which is the alligator clips you see connected to the L298N.

I am measuring the 7.9V from just connecting the wires from the battery pack to the multimeter.

The USB is still connected when I am using the battery.