Pi2 and Zero both died on me. What could be the reason?

[FLDJF713]

I had just bought a Pi 2 and everything was working fine. I had it powered via my Macbook USB and was simply running a VNC client to do some basic work. I unplug the Pi and then go to boot it up again, and nothing. Both the red and green lights stayed on.

I booted my Zero up with the same card and it worked fine. I put a fresh install of Rasbian on another card and try the 2 again. Same issue, no response but the lights.

Then today, the same thing happened to my Zero. I unplugged it and then plugged it back in. The ACT light wouldn't go on.

Did a fresh install again and tried another card, nothing.

I should mention that at the time of reboot, each Pi was running at 100% for about 15 minutes, but was in a well-ventilated and rather cool room. I've tried 5 different SD cards and power supplies.

[W. H. Heydt]

I would be inclined to try the Pis using an independent PSU rated for at least 2A. IF they don't boot, reflash the SD cards and if that doesn't work, start with new SD cards. USB port spec only calls for supplying 500mA. Since the Pis may be drawing a lot more than that, you may not be getting 5v even if enough current is supplied.

You may have corrupted SD cards.

[stderr]

I unplug the Pi and then go to boot it up again, and nothing. I unplugged it and then plugged it back in. The ACT light wouldn't go on.

No mention of properly shutting down the computers. Did you properly shutdown each of the pi computers or did you do what you said, just unplugged them? Then when you put a fresh install on them, as you say, did you look at the fresh install by mounting the sdcards in the system that you were using and making sure that things were sensible?

[MarkHaysHarris777]

USB port spec only calls for supplying 500mA. Since the Pis may be drawing a lot more than that, you may not be getting 5v even if enough current is supplied.

You may have corrupted SD cards.

Yes, I agree. You cannot power the PI 2 (nor the PI 3) from a usb port; just not going to work. This gets very confusing because the first Raspberry PI that was really popular (the B me thinks) could be powered from the usb port... in fact, it was common practice to power them from the 5v line that comes off the PL2303 usb to ttl serial cable; the serial cable was power as well as console... but that WONT work on the newer PIs.

[broe23]

Mark actually I had it happen to me while installing Debian Lite to a hard drive on my Pi 3. I had the drive plugged into the USB near the Ethernet and the external case for the hard drive was powered off of the USB on a hub. When I unplugged mine, the extra juice from the hard drive enclosure actually kept the Pi powered up, until I yanked the cord. It did not happen after I double checked everything and hooked it all up.

So yes it can happen in theory or when the stars and moon align that you could end up feeding power back through the USB if you have something faulty.

[Dis93]

Didn't you mention, on the Reddit thread you posted, you had your Pis on the carpet...

[FLDJF713]

Didn't you mention, on the Reddit thread you posted, you had your Pis on the carpet...

Nope, I was standing on a carpet and then went to the table where the Pi was sitting. However, I believe I would have discharged before as I have to pull on a metal chair to sit down.

[FLDJF713]

USB port spec only calls for supplying 500mA. Since the Pis may be drawing a lot more than that, you may not be getting 5v even if enough current is supplied.

You may have corrupted SD cards.

Yes, I agree. You cannot power the PI 2 (nor the PI 3) from a usb port; just not going to work. This gets very confusing because the first Raspberry PI that was really popular (the B me thinks) could be powered from the usb port... in fact, it was common practice to power them from the 5v line that comes off the PL2303 usb to ttl serial cable; the serial cable was power as well as console... but that WONT work on the newer PIs.

How could you explain how it worked for weeks perfectly fine with power from the USB port? I know it's not the correct way to power it, but it did work, so it's not impossible. The Zero and the 2 both worked fine under USB power.

[rpdom]

The Zero and the 2 both worked fine under USB power.

The Zero has no protection circuit to stop it being powered by the USB port.

The Pi 2B does have such a circuit - but it works because the power connection to the USB ports is disabled until the OS has booted to the stage of enabling the USB power. After that the power can flow both ways through the USB ports and the Pi will continue to run if the main power supply is removed (as long as something is providing sufficient current via the USB).

[asandford]

OP, were you 'back-powering' the Pis via the (pi) USB, or just using the mac USB to power via a USB A to micro-USB cable?

[asandford]

Yes, I agree. You cannot power the PI 2 (nor the PI 3) from a usb port; just not going to work. This gets very confusing because the first Raspberry PI that was really popular (the B me thinks) could be powered from the usb port... in fact, it was common practice to power them from the 5v line that comes off the PL2303 usb to ttl serial cable; the serial cable was power as well as console... but that WONT work on the newer PIs.

The OP didn't state that they were 'back-powering' the Pi, they may have just used a USB A to micro-USB to power it (most PCs will now deliver (within limits) whatever current the device needs).

[Dis93]

https://www.reddit.com/r/raspberry_pi/c ... _going_on/

[asandford]

https://www.reddit.com/r/raspberry_pi/c ... _going_on/

Interesting. I've just plugged a pi3 into my laptop USB3 port (a2u), and I get a rainbow square. If I power it from a 36W USB3 hub - fine.

[MarkHaysHarris777]

How could you explain how it worked for weeks perfectly fine with power from the USB port? I know it's not the correct way to power it, but it did work, so it's not impossible. The Zero and the 2 both worked fine under USB power.

Well, like asandford says, did you power the PI via the micro usb port (the main power port) or did you back-power the PI from the usb port?

This kind of discussion becomes tiring. The PI needs a good PSU, with a good cord, and should not be back-powered via the usb port. Now then, its your PI and you can do anything you want to it (as Joan says) including letting your dog use it as a chew toy... but I would not.

If you want your PI to run reliably and efficiently, power it up correctly. I don't know what else to say. Oh yeah, I power my PIs up correctly for almost two years now and I have never had any power related issues; not ever.

[asandford]

All that needs to be said is that phone chargers aren't power supplies, and the Pi can't negotiate its needs over (any)USB connection.