Pololu Robotics & Electronics
Menu
My account Comments or questions? About Pololu Contact Ordering information Distributors

Pololu Forum

Capacitor explode, what I have done wrong

Hi All,

Please refer to the picture details, that capacitor explode after I did power on, this is a Roboclaw 2X30 A connected to 2x DC brushed motor(wheelchair motor), S1,S2 was connected to Ground, B+ and signal (supposed to be ESC signal) of Management power board of Pixhawk 4, I did use hot glue to just make the connection still not lose on the power board, unfortunately that capacitor explode, pls can some tell me what I did wrong …I have basic electronic knowledge and trying to learn …thank you

Hello.

Did you do any testing with the RoboClaw where it worked properly before you put it in this bigger circuit?

Also, how and why were you using hot glue? Could you post some pictures showing your actual setup and all your connections?

- Patrick

Hi Patrick,

Before I connect S1 and S2 to ground, B+ and signal of Pixhawk power board I did connect S1 and S2 to FMU-PMW-out to avoid welding, the roboclaw had a green light but I could not get any result after arming the system, after that I thought to connect directly B+, Ground and signal I did use the hot glue on the tip of wires to make the connection firm and not lose (unfortunately I did remove them before I take picture) after I power on the capacitor explode and the positive tip of S2 on roboclaw side jumped from its place on the pin :man_shrugging: , I would like to know the right way to connect this set I need to get unfortunately another Roboclaw but I appreciate some diagram to connect them together with the Pixhawk 4 with right setting on Roboclaw side.

Kind regards

Jad

My understanding of the Pixhawk is B+ is equivalent to its power supply input to, 24V in this case. The middle pin on the RoboClaw input connectors where you connected the B+ voltage from the Pixhawk to the RoboClaw is a 5V output line, so connecting 24V to that would definitely cause some catastrophic failure, like the capacitor exploding.

You should not need to connect to the RoboClaw’s 5V output to send it signals; you just need the signal lines connected and a common ground. We are not familiar with the Pixhawk, so you might try contacting its manufacturer to check that this would be an appropriate thing to do.

- Patrick

Thank you Patrick that explains everything and why the wire jumped out some time we need to learn hard … thank you again

1 Like

To understand why electrolytic capacitors (GKG30086-05) explode, you must first know what electrolytic capacitors are? The metal foil is the positive electrode (aluminum or tantalum). The oxide film (aluminum oxide or tantalum pentoxide) that is in close contact with the positive electrode is the dielectric. The cathode is composed of a conductive material, an electrolyte (the electrolyte can be liquid or solid), and other materials. Because the electrolyte is the main part of the cathode, the electrolytic capacitor is named. At the same time, the positive and negative electrolytic capacitors cannot be connected wrongly. Aluminum electrolytic capacitors can be divided into four categories: lead aluminum electrolytic capacitors; horn-type aluminum electrolytic capacitors; bolted aluminum electrolytic capacitors; solid aluminum electrolytic capacitors