Fried RaspberryPi?

I bought a new PI for use with the Thunderborg, and I've just started testing it out by connecting it to 4 18650s. For some reason the Raspberry PI now heats up to insane temperatures on idle (I've seen >85C by using vcgencmd measure_temp), even if I don't even have an SD card in.

This seems to happen to the Pi even when connected to USB power now. Is it possible that the thunderborg might have overvolted and fried the pi CPU, or that I had a faulty pi?

piborg's picture

The bad news is that temperatures that high at idle imply the Raspberry Pi itself may be damaged. At a minimum it will be running slowly in an effort to avoid getting any hotter (thermal throttling: https://www.raspberrypi.org/documentation/hardware/raspberrypi/frequency...).

The good news is that it is not because of the batteries you are using. Four 18650s in series at maximum charge produce around 17V, which is well bellow the 35V maximum for the ThunderBorg.

The first question is how are things wired up at the moment? That includes anything connected to the Raspberry Pi (e.g GPIO wires) and the ThunderBorg (e.g. batteries). Pictures are always helpful for this :)

Thanks for the response!

Yeah, I'm pretty sure the Pi is damaged now, but it was brand new before I started using it with the Thunderborg so I want to make sure it wasn't something I was doing that damaged it.

I'm not able to take a picture right now, but the setup is very simple. I've placed the Thunderborg directly on the GPIO pins on top of my RPi4 Model B. The Thunderborg is then wired to a 4-battery pack holder I found on amazon with four Sony/Murata VTC6 18650s - thunderborg script reported 15V. I wired up one motor, the PiBorg Motor 12V 300RPM - 37mm. Other than that there was nothing connected.

Is there anything I could have done with the Thunderborg setup which might have caused this? I'm just worried about replacing the Pi and then having the same thing happen again, but I'm not sure if the Pi was always faulty.

piborg's picture

From your description the only problem I could see happening is if the battery pack was connected to the wrong terminals - either with +ve and -ve swapped, or connected to one of the motor terminals by mistake.

It would also be possible to fit the batteries in the battery pack backwards, but I would expect you to see a different voltage in that case (15V sounds about right).

Usually I would suspect the wiring between the ThunderBorg and the Raspberry Pi as the GPIO connections can be damaged fairly easily if the wrong power is connected to them. This should not be possible with the board fitted directly onto the Raspberry Pi.

Usually a faulty ThunderBorg will fail to communicate with the Pi. Since you are able to read voltages back from the ThunderBorg I think it is likely that only the Pi is not working properly.

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