Maker Pro
Maker Pro

powerbank low power switch

tonyeson

Nov 26, 2016
4
Joined
Nov 26, 2016
Messages
4
Hello, I'm powering a raspberry pi 1 (model A) from a small power-bank. I read somewhere that doing this will put my sd-card in danger as it might get corrupted when the power-bank is running out of power, so I need a way to directly and completely cut the power supply when the voltage levels are getting low.

the idea is to put a ~ 5v relay on the power-supply from the power-bank to the pi, so that when the voltage drops, the relay are cutting the power, will this be a working solution, or are there any better ways to check for low voltage on power-bank powered pie's ?

the sd-cards seem to be corrupted when the pi is running on rly low voltage, not when the power is cut of the pi (eg. pulling the plug).
 

hevans1944

Hop - AC8NS
Jun 21, 2012
4,880
Joined
Jun 21, 2012
Messages
4,880
The Rpi doesn't draw much current. Perhaps you could use a MOSFET switch to apply power to it, using a comparator to determine when the battery terminal voltage is too low to turn on the MOSFET? A relay has some advantages if you want to turn it on when power is okay and let it drop out when the battery voltage gets too low, but not low enough to corrupt the SD memory. Some trial and error might be necessary to find just the right relay with the right drop-out voltage, but that would be a simple solution. You should latch the relay through its own N.O. contacts, so when it does drop out it stays dropped out until you press a momentary SPST ON switch wired in parallel with the N.O. relay contacts.
 
Top