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[SOLVED] Powerbank: quick question!

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marvins42

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Hi all,

I'm trying to supply 5V to a circuit (previously, I was just using batteries, but a powerbank would be a nicer solution, if it works!). Just from testing the power banks, I'm getting about 3.5V out; if I push the power button, I get 5V for a few seconds, then it goes back to 3.5V. Powerbank data: 3.7V battery (internal), 2600mAh, Output: 5V/DC 1A. The model is VOLTCRAFT PB-14 Li-Ion 2600 mAh. If anyone could give me some pointers on this, that would be great! :) Thanks!
 

What are the current requirements of your circuit? Maybe the power bank protection is activated because you try to get more than 1A or you circuit includes an inductive load that my give a surge (sudden current draw).

Another reason may be if the power bank has a circuit that shuts down the output when the drawn current is below a threshold, so maybe your circuit uses too low current and the output thinks there is no load and shuts down. You could test by adding a resistor as a load.
 

Thanks for the reply! It's the latter; I'm drawing much less than 1A, and I just tested it with a load (it shut off after a few seconds). Is there a way to bypass the shutdown circuit? I'm worried about taking the thing apart, but if it's not a terribly hard fix, well, it's not working anyway. :)
 

Hi

Check the voltage of the power bank by connecting it to a mobile. also verify the charge level of the batteries. In such cases if the power bank batteries are at low charge the output wont be stable as you( marvins42 ) have mentioned.
 

marvins42 said:
Thanks for the reply! It's the latter; I'm drawing much less than 1A, and I just tested it with a load (it shut off after a few seconds). Is there a way to bypass the shutdown circuit? I'm worried about taking the thing apart, but if it's not a terribly hard fix, well, it's not working anyway. :)
Click to expand...

Usually there is an IC circuit inside so I'm not sure you can bypass it. You can try to take a look at the internal circuit assuming there are screws to open the case without braking it.

You could make your own power-bank using

a battery (e.g 36650 lithum type)

a MT3608 step-up (less than a dollar in ebay) or any other similar board
s-l300[1].jpg

and a USB charger like TP4056 or similar
s-l300[1].jpg

They can all be stack up on the battery case, one charge board to charge the battery (unless you want to charge it with an external charger) and one step up board to give 5V output (with or without USB plugs)
IMG_20160201_175938.jpg

Or maybe modify the existing power bank adding a different step up circuit directly to the battery.
 
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