This is a post by error, please see the next message.
I have a Dagu 4WD Wild Thumper chassis driven by two Pololu 18v15 controllers. Yesterday I fiddled with the software, and a little accident happened, and the rover rolled over to its top. One of the controllers got burned, like this:
The picture is a bit blurry, sorry about that. The damage can be seen under the “Engage your brain” label, the burned wire crosses the end of the URL. It also had a bad burnt smell. Now the error flags say “Low VIN”, and it measures 0 volts, whereas the other controller works fine, and shows the real voltage. (I have ordered a replacement controller.)
I have two questions:
- Why did that happen? I remember reading in the manual that the wires should be able to handle 6.5 Amps, so I made sure to use proper cables. Is the board itself prepared for this?
- What can I do to prevent it from happening next time? (Other than not rolling it over.)
Thank you in advance,
Sorry for the double post, I missed the message about approval, and thought the first message just disappeared
A somewhat better image:
Also it is visible that something is wrong at the upper left corner near the GND label.
It is difficult to tell without knowing more about your system, but the location of that burned trace makes me suspect there might have been a short between VIN and GND during the rolling accident. That could have happened if a piece of conductive material temporarily bridged VIN and GND on the right side of the board in your picture. If that is what happened, you could prevent it be using a protective case or cover that ensures nothing conductive can connect various parts of your controller together.
I know you mentioned you ordered a replacement, but the damaged controller might still be working. You might try soldering a wire between the VIN pins on both sides of the board to jump the burned trace. If you decide to use the damaged controller after that, please note that it is difficult to tell if anything else might have been damaged in the accident, so I recommend being cautious until you have made sure whether it still works.
I am not entirely sure I understand what you are asking about in your first question, but it sounds like you want to know if the damaged trace on that controller can handle 6.5A. That trace is just meant to make the power from VIN available for other uses, so the trace itself is not designed to handle as much current as the controller is rated for. However, the Simple Motor Controller 18v15 can handle 15A continuously, which means that the current path for the outputs can handle 15A.
thank you for your answer. I’m rather sure that there was no cable or anything else that would have caused such a short circuit. However, I’m using brushed motors, and that might have been the cause, because I learned that those might short circuit in case of a big mechanical impulse.
I’ll try to fix the controller, thank you for the info!
If a brushed DC motor fails as a short, the motor should not be running. Are the motors that were connected to the damaged controller still working?
By the way, did you connect your power supply to VIN on the left (near the motor outputs) or right side (logic side) of the board? If you connected power on the right side, it makes sense that that VIN trace would burn up if the motors drew a lot of current.