Currently, I have a USB powerbank powering my arduino Uno which powers my micro servomotor. I would like to have the motor running for long periods of time (~24 hrs). Sometimes, I am able to achieve this run-time but in most cases the power bank shuts off after about 3-4 hrs of running. I am not quite sure about the variability. It seems that my powerbank has a current threshold (don't know exactly but probably 50-60 mA) and my arduino/servo motor are probably right at that cut-off.
What is the easiest way to handle this problem? Could I program my arduino to draw more current from the power bank (have it calculate pi to many decimal points?)? Or, would just buying a proper grade resistor do the job.
Thanks
Best Answer
A direct resistor connection will work, but will be very wasteful. Trying to calculate PI won't actually increase the load much. Instead, a simple intermittent pulsed load will work. A resistor and suitable N-channel transistor or mosfet, pulsed every n seconds would trick the power supply into thinking there is a large load, but also reduce the average load, hence longer battery life.
simulate this circuit – Schematic created using CircuitLab
A 1 second pulse of 75mA every 10 seconds is only a 7.5mA draw over 10 seconds, compared to a constant 75mA load.
Adjust the period and load as needed.