#Lazyweb Question. If I have USB battery banks that turn off if the load is too low, what's the consensus on tricking it to stay on? A resistor across the power lines (what resistance and power rating?), or something like a 555 that periodically puts a big load (size?) every few seconds?

@rc2014 I've seen both of those tricks used. I used a resistor for a project I helped my brother with because it was only going to reduce battery life by like 20 minutes over the course of 4 hours

@rc2014 i know there is a commercial resistor based option. i could also find out which specific random cheap power bank we found doesn’t do that

@rc2014 there was a pcb that pulled 100ma or so in short pulses for exactly this. Tindie IIRC

@MLE_online Any idea of the rating of the resistor you used?

@rc2014 I don't remember. I just measured the current draw of the bluetooth module and added whatever amount of resistance was required to bring the current consumption above the bare minimum for the usb battery

@rc2014 or https://thepihut.com/products/power-bank-keepalive-assembled?srsltid=AfmBOoqN4HCahW0mH-HN2DyNq028T5oofE9srnnvzse-iBUQzJ1sqxAn

Or

https://www.instructables.com/Current-Pulsing-Keeps-Power-Bank-Active/

@Extelec Thanks. Ideally I want something I can do with parts I have here before Friday morning.

@rc2014 the instructable has a 555 circuit

@rc2014 or 4-5 fully loaded rc2014s should do it.

@Extelec The Instructable also says "I have put the circuit into a small plastic container and wired a USB-A to USB-A cable". Where am I going to get a USB-A to USB-A cable ;-)

@MLE_online Thanks

@rc2014 if only you had 75 or so.

@rc2014 I recently had to do this @ job. Used one of those small USB power meters.

EDIT: realized this is probably more of a circuit design question... disregard

@felipe Thanks. No, not really a circuit design question. More like finding a way to bodge something in to working before the weekend without too much effort or expense :)

@rc2014 @MLE_online
I used a 1-meg pot and kept turning it down (lower R) until my brick stopped turning off. Since I was just applying load in addition to the circuit I was running it didn't take much, but I didn't measure what the pot was drawing.

@rc2014 my experience is that you need about 50ma.

Depends on the exact chip in the power bank.

I have seen some that need as much as 150ma draw to stay on.

There are circuits that do a pulse draw to keep it awake with minimal power loss.

@Robsonde Thanks. That 50ma ball park figure is good to get me started.