I'm needing a cheap UPS solution for an arduino project I'm working on to cover any power cuts etc, and I'm also needing a voltage regulator to take AC to 5V DC. So, I'm planning on using a USB AC adapter as the voltage regulator and a powerbank for the UPS such as this one.
The actual powerbank though it has:
Input 5V 800mA
Output 5V 1A
My project is going to only draw at most 80mA, and the powerbank has a capacity of 2600mAh which will see me through even a very severe power cut.
My question is, is it considered safe to essentially be charging a powerbank while drawing power from it, and is this whole idea a suitable way of achieving what I want to achieve?
My question is, is it considered safe to essentially be charging a powerbank while drawing power from it,
Check the voltage with it on charge. If it is still 5V ± 0.25V it should be safe to use that way.
I have a powerbank that I use to power a standalone 328 project. My powerbank will shut down if less than about 30mA is being drawn. It doesn't matter much with my current project as it draws approximately 50mA, but a different project was lower power and the bank would shut down unless I added a load (LED) to get the current over 30mA. On my bank the 30mA current doesn't need to be constant. I pulse the LED for 30mSec every 5 seconds and that keeps the powerbank on.
I don't know if all banks have the auto shutdown but thought I might mention it.
Generally, the 5v USB powerbanks have a lithium 3.7v battery inside. The input 5v will charge the battery with a voltage regulator to 3.7v to 4.2v.
Then the output uses a stepup regulator to provide 5v out.
It should be safe to charge and discharge at the same time. Great for a UPS.
@bill2009, Was you drawing more current than the powerbank was rated for? Why do you think it cut off? Maybe you were drawing to little current, so it shut down the step up regulator?
Remember what groundfungus said: "I pulse the LED for 30mSec every 5 seconds and that keeps the powerbank on".
