5v powerbank as power supply?

[tzenobite]

hi people, here again.

while i'm testing the box so far, looking forward to add the mixer (and more input channels) got a idea about powering the thing
since the pedal needs a 9v battery, the mixer another one, and since each 9v battery gives only 620mah each (for about 5$ each at a big electronics mall store) what do you people think about using a 5v rechargeable powerbank with a step-up module?
now, on a famous online store a 20000mah powerbank costs 20-25 euros, like 4/5 9v good batteries and has about 25/30 batteries energy... plus, i can recharge the box at home or in my car or elsewhere with a common phone charger
i saw there's online a cute 5v>9v step-up CABLE that'l be simple plugged to a usb port and gives 9v@800mah for a couple $

what do you think?
thanks!

[Mark Hammer]

The battery pack itself is absolutely fine, and a nice green and cost-effective solution.  The potential problem crops up with the conversion from 5V to 9V.  That sort of conversion is generally done via circuitry that uses high-frequency clocks.  That, in itself, is not problematic.  The potential problem arises with using it to power other circuits that also use HF clocks, such as pretty much any digital pedal, and any pedal using a bucket-brigade chip.

The converted 5-to-9 CAN be appropriately filtered to avoid problems, but I suspect neither of us knows whether the converter device you're thinking about buying will do that.  It may well be that the optimum solution is to buy two of the rechargeable packs, run them in series for 10V, and then drop the 10V, where needed, to 9V via a couple of diodes. 

[Gus]

A thread from 2015
http://www.diystompboxes.com/smfforum/index.php?topic=112815.msg1042501#msg1042501

[Rixen]

QC fast charge equipped powerbanks are capable of outputting 9V or 12V @ 1.5 A on the USB V+ line when commanded to with appropriate signalling on the data lines (basically asserting voltage levels at particular times). I've used this to successfully power 12 V equipment (though not audio, so can't vouch for noise).

There's numerous advantages to using powerbanks, namely they incorporate all the battery and charge management and you can charge them from multiple sources.

[tzenobite]

neither of us knows whether the converter device you're thinking about buying will do that.

since i've already a battery pack i'm using with the phone i'll buy a step up module give it a try and see (this: http://www.ebay.com/itm/DC-DC-Converter-5V-to-6V-9V-12V-Adjustable-Output-USB-Step-Up-Boost-Power-Module-/271306601322?hash=item3f2b22336a:g:rK8AAOSwo4pYfCZ3)
if the pedal works well enough it will be better to have one battery pack when i have to recharge it

[tzenobite]

QC fast charge equipped powerbanks are capable of outputting 9V or 12V @ 1.5 A on the USB V+ line when commanded to with appropriate signalling on the data lines (basically asserting voltage levels at particular times).

you think i'll be possibile to get 9v from these powerbanks simply connecting a 9v load? or they needs a smart counterpart like a smartphone and the like?

[Gus]

a link
https://www.youtube.com/watch?v=b-46fmEB0eM

[Rixen]

QC fast charge equipped powerbanks are capable of outputting 9V or 12V @ 1.5 A on the USB V+ line when commanded to with appropriate signalling on the data lines (basically asserting voltage levels at particular times).

you think i'll be possibile to get 9v from these powerbanks simply connecting a 9v load? or they needs a smart counterpart like a smartphone and the like?

No, you need to:

− Apply a voltage between 0.325 V and 2 V to D+ for at least 1.25 seconds (I use 1 diode volt drop, 0.6 v for this)
− Discharge the D- voltage below 0.325 V for at least 1ms while keeping the D+ voltage above 0.325 V
− Then apply the voltage levels below to set the output voltage. (must keep the D+ voltage above 0.325 V)


D+                 D-                            OUTPUT
>2                    0.325 to 2V                 9V
0.325 to 2V      0.325 to 2V               12V
(abridged- there is also a high current 5V mode, and a 20V mode)

I use 4 diodes to generate the D+ voltage, one diode for the D- voltage, and an arduino pro mini to shunt some diodes to ground as per the sequence above. Every minute it is necessary  to apply >45mA load to the powerbank to prevent it entering sleep mode.

It is not a complex circuit, neither is it difficult code (18 lines).

[dschwartz]

Why not just use two 5v powerbanks in parallel? If they work like batteries, it should give 10v

[thermionix]

Why not just use two 5v powerbanks in parallel? If they work like batteries, it should give 10v

You mean in series, as MH suggested above?

[dschwartz]

Why not just use two 5v powerbanks in parallel? If they work like batteries, it should give 10v

You mean in series, as MH suggested above?

Oh yes, in series ..
Some of those things are cheap.. you could use 4 for 2 independent outputs and connect their charging input in parallel...it should work fine