Zero Pi, hot USB flash drive

I know it is not distro related but a general Pi question. I thought I’d ask it here, since, my guess, many use USB drives with DietPi.

So, I decided mainly to use DietPi because of built in ability (so, I don’t have to tweak myself) to boot from SD card but to use a USB drive as a main storage. This keeps sd card corruption to a minimum. My project would require to put the Zero Pi in a very inconvenient location, I hope to never touch it physically again after the installation. De-installation would suck.

However, I find that USB drives get hot. I mean, not burning but uncomfortable hot to the touch. I wonder if there is a way to minimize heat of USB flash drives with Pi.

The only way to prevent heat would be to limit the USB transfer rate. As for how to do this, no idea.

USB pen drives usually run hot, especially the non-branded ones.
A USB 3.0 pen drive (thats capable of > 40mb/s transfer rate read and write) is probably your best bet as it won’t be able to reach its maximum transfer rates on USB2.0, hence, reduced temp.

Thing is, the drive continues to be relatively hot even if I leave Pi to be idle for hours. Since most logs are written to a memory, there shouldn’t be any data written or read, at least in sizable amounts. But the USB drive does not cool down. I tried others, they keep about same temp.

I get the same with my USB drive (sandisk nano usb3 16GB) when its idle. Its warm, but not hot.

I did power usage test on my drive:
idle = 0.00amp
load = 0.26amp max, 0.18amp average

So, it must be the case that these devices are terrible at dissipating heat?

I also think the heat of the RPi ARM is a factor (especially RPi3). It seems to dissipates alot of that heat to other components on the device. For me, both USB and even the HDMI connector gets really warm. RPi 3 SoC at nearly 100 °C, reporting 80 °C - Raspberry Pi Forums