Digitakt modified with internal battery

laikrodiz · July 6, 2019, 4:15pm

Digitakt doesn’t turn on because it may go in some kind of protection mode when it turns off due to lack of power. Just leave it charging for 20 minutes then turn on Digitakt with PSU in. It will be charging and working off PSU easily.

In general, this doesn’t happen and as soon as you insert the power supply, it should switch back to it. I noticed this behavior only when the battery is discharged below some critical level. Then the fix is as I mentioned — leave it charging with Digitakt off for 20 minutes.

Kloanhead · July 6, 2019, 8:09pm

Perfect

Lameller · July 14, 2019, 8:24am

Everything is now up and running. Thankyou so much for all the help😀

gbel · July 23, 2019, 7:21pm

Just wondering if anybody else that did the mod experienced this issue:

I used same battery cells and BMS as listed but charged it to the max 12.6V.

Digitakt works with power supply but if I remove the plug it freezes turned on. Sometimes if I turn on without the power supply it takes a little longer than gets stuck on Boot Screen.

I think the issue is that I overcharged the battery pack and the unit has some sort of protection against it.
Will try to take some load of the battery pack and see if that solves the issue.

Any help is welcome!

laikrodiz · July 23, 2019, 8:46pm

Did you try keeping it at ~12v and running for some time? Using a standard Elektron PSU will only let you charge the battery to around 12.1v.

The symptoms you’re describing look more like a power disconnect that’s happening randomly somewhere. From my experience, when Digitakt goes into protection mode, it refuses to turn off for 10-15 minutes. But I only experienced this behavior on an undercharged battery, not on an overcharged one.

gbel · July 24, 2019, 12:40am

It was indeed a broke connection within the cells… Unfortunately I got the BMS fried while fixing or maybe by the bad connection.
I wish there was a way to debug those BMS as I got 2 not working in the process. Guess I’ll have to wait for more boards to come in the mail and watch out for bad solder joints on the next one.
It’s weird because on of the BMS reads 11v but can’t charge anything. Some of the mosfets are probably gone

HiGrade1 · July 24, 2019, 12:51am

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?

laikrodiz · July 24, 2019, 8:25am

No one will tell, until somebody buys it and looks inside

jeanclaude · August 1, 2019, 3:39am

Curious to see this build!

Crushloops · September 23, 2019, 2:00pm

Crushloops · September 23, 2019, 2:01pm

Crushloops · September 23, 2019, 5:13pm

Augenadler · November 23, 2019, 12:58pm

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.

laikrodiz · November 23, 2019, 1:31pm

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.

Augenadler · November 23, 2019, 2:20pm

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

laikrodiz · November 23, 2019, 3:00pm

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.

Augenadler · November 23, 2019, 3:29pm

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.

TRAINTRACS · November 26, 2019, 4:03pm

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!

Augenadler · November 26, 2019, 4:14pm

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

TRAINTRACS · November 26, 2019, 4:47pm

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.