Raspberry Pi Forums

hi
i've made a script to control a fan on the case of my Raspberry Pi 3 model B.
when temperature goes over 46.C the fan turns ON... but unfortunately at the same time the Red Power led of the device turns off as well and i don't think it's a good thing at all.

i am controlling the fan through a MOSFET. (IRFZ44N) set on the gpio 4 which acts like a switch. The fan is then connected to the 5v pin.

what do you think about this issue?
thanks

komarek wrote:hi
i've made a script to control a fan on the case of my Raspberry Pi 3 model B.
when temperature goes over 46.C the fan turns ON... but unfortunately at the same time the Red Power led of the device turns off as well and i don't think it's a good thing at all.
i am controlling the fan through a MOSFET. (IRFZ44N) set on the gpio 4 which acts like a switch. The fan is then connected to the 5v pin.
what do you think about this issue?
thanks

How much current does the fan require? It's possible that it's too much to be supplied directly through the Pi and the PoWeR led is turning off as (one of) the low voltage warnings. What devices do you have plugged in to the USB ports? Is the total current for those, plus the fan, close to the 1200mA limit?
Trev.

The red power led going off means you're pulling too much power from the power supply and it's going undervolt. A better PSU (such as the official 5.1V 2.5A PSU) may help, alternatively you might need to add a separate PSU for the fan.

Yes, it's a power issue. I had this exact problem, except the device drew enough power to reboot the Pi. You can try a bigger (more amperage) power supply, or power the fan with a separate device altogether.

ok guys
this makes sense
because i already had a NOTICE from the system at the first boot wht a YELLOW LIGHTIN BOLT.
actually i am powering the device with an iphone charger and i guess it's not the best choice..
so, considering i can't measure the current at the moment, not having an amperometer, i think the problem should be fixed 100% with an official PSU

right?

irab88 wrote:Yes, it's a power issue. I had this exact problem, except the device drew enough power to reboot the Pi. You can try a bigger (more amperage) power supply, or power the fan with a separate device altogether.

except the red led issue
assuming i am not plugging any other device to the usb ports... what's the risk to keep it this way?

komarek wrote:

irab88 wrote:Yes, it's a power issue. I had this exact problem, except the device drew enough power to reboot the Pi. You can try a bigger (more amperage) power supply, or power the fan with a separate device altogether.

except the red led issue
assuming i am not plugging any other device to the usb ports... what's the risk to keep it this way?

USB devices that really need 5v probably won't work. You may be risking SD card corruption. Much better to get a properly rated (and built) PSU. Chargers can be pretty sloppy about their voltage regulation since the battery charging circuits in most devices don't care so long and the voltage is enough over battery voltage (3.7v) to charge them.

thank you all