SD card gets hot when power fluctuates

[oglo]

Hi

a few days ago a was fiddling with an ArchLinux distro on my Pi B. I had the Pi powered by my laptops USB which I had to reboot. I didn't give it much of a thought until I (couldn't log in and) noticed the heat and smell coming from the card. Cycling the power of the PI directly (pulling the plug) fixed the issue and fortunately without data loss.

However, I fear for my safety should this happen again. The card got so hot it might even start to burn!

How would I implement a safeguard that kills power supply if things get hot? Obviously nothing that runs on the Pi as it already was in an exceptional state and unresponsive to commands.

[PeterLustig]

Same problem here. Happened only once (a reboot fixed it), but should be taken care of, as this really poses a safety risk and could lead not only to data loss, but fire and negative publicity for the PI.

The problem is espcially relevant in headless mode, as the user does not physically interact with the device and the device might be located somewhere remote.

[drgeoff]

Not trying to downplay the seriousness of this but the title of the thread links the SD card getting hot to when the power fluctuates. However there is nothing in the above two posts which truly supports that.

If the real circumstances which cause the SD card to get hot can be ascertained and reported it will surely increase the likelihood and speed of a fix.

[Davespice]

Wow. This is a new one. I have never heard about this before.
What would help a lot is if you could find a way to repeat it, some steps that will make it happen every time.
Then someone else can try to reproduce it and see what is happening.
Can you post the make and model of your SD cards too.

Also, are you using a Micro SD to full size SD card adapter?

[oglo]

Also, are you using a Micro SD to full size SD card adapter?

Mine is a µSD. SanDisk I suppose.

[oglo]

Not trying to downplay the seriousness of this but the title of the thread links the SD card getting hot to when the power fluctuates. However there is nothing in the above two posts which truly supports that.

If the real circumstances which cause the SD card to get hot can be ascertained and reported it will surely increase the likelihood and speed of a fix.

What kind of support do you need? It happens, system gets unresponsive and you (almost) burn the tips of your fingers. It appears to me the speculating is on your side. I suppose a simple test bed would be: drive the TTLs (or which ever technology is used) outside their secure voltage margins.

All *I* want to know is: Which method shuts a system down *reliably* without using Pi sensors.

[Burngate]

To work out what happened, more details are needed.

What software? (you say ArchLinux as OS)
What was running when you rebooted the laptop?

What was connected to it? Anything on the GPIO? What USB dongles? Network? HDMI?
Were you logging in with a keyboard (and mouse) or over SSH?

The title says "power fluctuates". Have you evidence of this? (apart from rebooting your laptop, which may or may not cause the power to fluctuate)
Did you measure the TP1-TP2 voltage?

The SD card is driven from 3v3, which comes from a regulator - RG2 - did that also get hot?

Your last sentence - "All *I* want to know is: Which method shuts a system down *reliably* without using Pi sensors" - opens a whole can of worms.
Do you want an external temperature sensor, and software to shut the Pi down with sudo halt ?
Do you want a watchdog of some sort, to pull the plug when the Pi stops responding (having crashed)?

[rpdom]

I believe I have seen a report of one other case where a microSD card in an adaptor had got very hot and failed. It turned out to be either a bad adaptor or a bad card (probably fake).

Mine is a µSD. SanDisk I suppose.

If you're not sure, then it is unlikely to be a SanDisk. Even if it is SanDisk branded there is still a chance that it is one of the huge number of cheap copies, unless you bought it from a reliable source.

[boyoh]

I can't understand why you are powering the Pi from the Laptop USB port
You would be better using a 5v 1000ma (1amp) power adapter
You said your SD card gets hot when powering from your Laptop

If you still whant to use the Laptop USB as the power supply for the Pi
If you have a multi meter check the voltage on pins T1 & T2 on the Pi
While using the Laptop USB, if the voltage is 5v .that should be ok,
But if the voltage is well down, it could be due to two things.

1. The Laptop USB buffer output is not supplying enough current
To drive the Pi.

2. You have fault on your Pi, that is pulling the voltage down
Due to the high current it is taking , this would cause
Components to get hot