I think my Pi either just over heated, burned out, or shorted out, please help..

Riverstorm

@spruce_m00se said in I think my Pi either just over heated, burned out, or shorted out, please help..:

@stoo I understand that, but Ive never seen a "fuse" that blows when the voltage is too low. Normally they are for high voltage. It makes no sense to me how a fuse can blow or trip from low voltage.

I think what he's saying is the fuse shouldn't trip from low voltage. It does give you a warning indicator (via lightning bolt) under a certain voltage but I don't believe the Pi shuts down or trips when the voltage value goes from high (normal) to low (undervoltage).

I think you may see other issues like corruption, reboots, powering down, etc. due to under-voltage.

stoo

@spruce_m00se To my limited understanding, when you overload a switched-mode power supply the voltage will drop. The components it is powering (the Pi in this case) will then try to draw more current to meet their power demands.

Certain components will be unable to handle an increase in current, hence the overcurrent protection. In this case the overcurrent is caused by low voltage, which is caused by a PSU that is not capable of supplying enough power. Polyfuses trip by heating up when the current exceeds a certain value.

I am soooo not an electrical engineer and I know very little about electronics, so ~~I'm sure there are many factors here I'm not considering~~ this is probably just plain wrong. Someone with more knowledge should feel free to ~~jump in~~ correct me in the harshest terms. :P

I should probably just remove this reply as the more I read it, the less sense it makes. I think I'm conflating two separate conditions.

spruce_m00se

@stoo My understanding of ohms law and electronics is that you take votlage and amps to get wattage, and in reality the fuse can pass a certain amount of watts.

That doesnt change as far as I know, essentially if you have a 10a 12v fuse you can bung 24v 5a through it, or 6v 20a.

spruce_m00se

However , thinking about it a bit more, the higher the voltage and lower the amps, the less the resistance of the cable/fuse causes issues with heating etc, and lower voltage and amps cause higher heating due to resistance,

since polyfuses (according to wikipedia) "trip" from the heat build up during use. The lower voltage and higher amperage would heat it more, thus making it "trip"