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Digitakt 2 internal battery mod - Printable Version

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Digitakt 2 internal battery mod - Moos - 11-08-2026

   
   
   
   
   
   
Hi all. 

I wanted a battery mod for the digitakt after having sold my op1 and opz.
The plus side is that I can charge the digitakt with my usb c phone charger and use it on the go. 
I’ve attached some images and the schematic. All in all it cost me around 50 

I used Claude to debug the project and as such, I’ve asked it to write a description which is very accurate:

What you need
Tools:
  • Drill
  • Dremel with a milling bit
  • Soldering iron and solder
  • Multimeter (you need it to set the converters)
  • Kapton tape and heatshrink
Parts:
  • 20 AWG wire
  • USB-C Power Delivery trigger board, set to 9 V
  • Boost converter (XL6009, buck-boost version), set to 15 V
  • CC/CV buck converter (XL4015), set to 12.6 V and about 1 A
  • 1N5822 Schottky diode
  • 3S common-port BMS with its balance lead (I used a Daly)
  • 3× 21700 cells (Samsung INR21700-50E, 4900 mAh) plus holders
  • 3 A slow-blow fuse with holder
  • Optional: a TP4056 single-cell charger, to pre-balance the cells
How it works
The battery is wired straight onto the Digitakt's DC input, before the power switch. The original switch therefore turns the battery side on and off too, and nothing drains the pack while the Digitakt is off. The USB-C side is purely a charger: PD board (9 V) → boost to 15 V → CC/CV buck to 12.6 V → diode → pack. The diode stops the battery from leaking back into the charging electronics.
Steps
  1. Charge each cell separately to 4.2 V, for example with a TP4056. Make sure they're within about 0.05 V of each other. The cheap BMS boards balance poorly, so start balanced.
  2. Build the pack and connect the BMS. I number the cells the way Daly does: cell 1 sits at the pack's minus, cell 3 at the plus.
    • Wire the cells in series: cell 1 + → cell 2 −, and cell 2 + → cell 3 −.
    • Pack − (cell 1 −) → BMS B− with a thick wire.
    • Solder the balance leads, but don't plug the connector into the BMS yet:
      • B0 → cell 1 − (pack −)
      • B1 → the cell 1 + / cell 2 − joint
      • B2 → the cell 2 + / cell 3 − joint
      • B3 → cell 3 + (pack +), directly at the cell, not after the fuse

    • Check with a multimeter, black probe on B0. B1 should read about 4.2 V, B2 about 8.4 V, B3 about 12.6 V. If any reading is off, fix it before going on, because a wrong balance lead can destroy the BMS.
    • Only then plug the balance connector into the BMS.
    • Put the fuse right at the pack + terminal (cell 3 +). The other end of the fuse is your "pack +" from here on.

  3. Set the converters before connecting them to anything:
    • PD board to 9 V (and save it as the default)
    • XL6009 to 15 V
    • XL4015 to 12.6 V without load, measured before the diode, and the current limit to about 0.8–1 A

  4. Wire the charge path:
    • PD board → XL6009 → XL4015 IN.
    • XL4015 OUT+ → diode (stripe toward the battery) → pack +.
    • XL4015 OUT− → BMS P−.
    • Important: the PD board's and XL6009's minus go only to the XL4015 IN−, never directly to P−. Otherwise you bypass the XL4015's current limit.

  5. Connect pack + and BMS P− to the + and − pins of the Digitakt's DC jack. These are before the power switch, which on the DT2 cuts both + and −.
  6. Drill and mill a slot for the USB-C port, and mount everything securely with Kapton tape over all bare metal.
  7. Test before closing it up. Unplug USB, switch the Digitakt off, and measure the pack voltage at the DC jack. Then do a first charge while keeping an eye on things, and check that nothing gets more than warm.
Result
  • It runs fully off the battery, and the power switch works as normal.
  • It charges from any USB-C phone charger that offers 9 V PD. The original Elektron PSU also still charges the battery.
  • You can plug and unplug USB while playing without it hiccupping. Charging while playing works too, but slowly.
  • Expected runtime is around 4 hours on my 3 × 4900 mAh pack. I'll update once I've done a full run-down test.
Disclaimer: lithium cells inside a closed case are no joke, so do this at your own risk. Only use the original Elektron PSU on the DC jack, not a stronger supply. Opening the case probably voids your warranty.