would this work - just as a standard external battery pack?
if so, i imagine it could work internally with some modifications…
has built in BMS, and it uses one port for power in/out.
thoughts?
No one will tell, until somebody buys it and looks inside 
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Curious to see this build!
Did you think about a version with 4s and a stepdown to 12V? This should really pump the battery lifespan with 18650ies.
I’ll check on that, bc 18650 are widely available to buy new or can be scraped off of old laptop or ebike batteries easily.
That would require a separate charging port, as 12v default Elektron charger wont work with 4 batteries. Doesn’t look an elegant solution to me.
As to 18650s in general, I’m using them in my Octatrack MK2 mod and first prototype of Digitakt. Worked fine, but had smaller capacity.
Hm… I’ll check that with a stepup converter. Just ordered some parts.
When charged to 14.8V, the 4s should last for over 8h on the DT
So my inital idea is to take the 12V input, step up to 14.8V or whatever the BMS needs for 4S, charge the batteries and stepdown the output to 12V for the internal PSU.
That way the power port can stay and the unit would still work with 12V on the input.
I think you only had the poor battery life bc the cells were not using their voltage range.
Any details on your OT2 project?
Cheers,
Jasper
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The whole step up/step down thing seemed like an unnecessary overcomplication to me, considering an option of just buying a larger battery at the same price. But it may work for you, I don’t know.
As to Octatrack I used 18650s as larger batteries wont fit due to crossfader placement. The good thing about OT is that it can work from much lower voltages, then DT, easily going to as low as 8.5V. That allows a more efficient battery discharge and gives similar 5-6 hours of time on smaller cells.
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That’s perfect on the OT2, 5+h is sufficent.
The thoughts with up- and downstepping on the DT mod is just for getting the full runtime on 18650 cells, that I got plenty of.
Also heaving the possibility to power other devices is awesome. That would not work with my solution.
That’s great to know! I’ve just been considering going the 4s route with a voltage regulator, but if it’ll work down to 9v then I don’t need to do that at all… Well, as long as my Virus TI will also operate at lower voltages, since I want to power them both. Thanks for the info mate!
I can check that tomorrow @TRAINTRACS, got a programmable PSU at hand. Usually the machines do not care about 0.5-2V under nominal Voltage. Some do, some don’t. Just never go higer 
That would be fantastic, thank you! Good to know about never going higher, though I kind of guessed that anyway. Much appreciated! It’s a Virus TI Snow btw.
Ah, I got a normal Ti. But the internal strucrure is more or less the same, so it should not matter.
Yeah, I’m sure it’ll be a very similar ballpark at least. Fingers crossed 
Just my 2 cents:
- My Digitakt freezes below 10.89v
- My OT MK2 freezes below 8.9v
So for example if I have a battery powered Digitakt, and a power-slaved OT2, Digitakt will last around 2:30, then freeze, but OT2 will be able to continue working from its “dead body” for at least an hour more.
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I will test that on the DT. 4x3400mAh 18650 should be able to power it for a loooong time. Hoping for 8h+ Not sure how to do it exactly, as the parts did not arrive today.
Bonus would be to have the 12V on the input to power another synth. Like the Mono Station for instance. That would be a movile dream team for me. Small yet powerfull.
what power bank is this?
No name aliexpress)