I’ve got a Macbook Air with awesome battery life 😁
I’ve got a Soundboks speaker with great battery life 😁
Just need to battery power my DDJ-1000 and Skanky becomes play-anywhere 👊
The catch is that the DDJ-1000 uses a fair bit of power and needs 12V. That rules out low-cost USB battery packs and it’s too power intensive to draw the 12V from the Macbook Air M2 USB-C port (its USB-C ports support USB PD so can provide 12V, but they aren’t rated for the 17W+ we need and it would kill the mac battery life even if they were anyway).
There are 12V battery power units out there that could be used, but they’re pricey. I got a spare chunky Soundboks battery with my Soundboks so why not use that?
Testing the current consumption of the DDJ-1000
Its mains power adapter is 12V DC max 3A.
Using a 12V DC power bench supply with current meter.
Power on startup: 1.6A
Idle no tracks loaded: 1.24A
2 tracks loaded, 9 hot cue buttons lit:
0 tracks playing: 1.29A
1 track playing, headphones active: 1.33A
2 tracks loaded, 2 playing, headphones active: 1.35A
This is as expected, the DDJ-1000 is just a midi controller and soundcard, so there’s no significant change in current for it when playing vs not playing. The MacBook Air running Rekordbox is doing all the grunt work.
Design
The Soundboks battery is a 12V battery pack and rated for lots of current (much more than we need – a Soundboks speaker can apparently draw up to 20A from it when being whacked at full power). Although the battery pack is 12.8V, that’s just its nominal voltage. Batteries are chemical and their output voltage depends on how charged they are, their temperature and the load. We need to assume its voltage will range anywhere from around 10.5V to 14V.
The DDJ-1000 power input is specified as 12V. Although it might be just fine running it at up to 14V, there’s no way of knowing it’s not going to damage the electronics inside, so let’s not risk it. We need to use a DCDC converter to convert our battery voltage to a perfectly smooth 12V for the DDJ-1000.
Typical DCDC power converters either lower the voltage they are given or boost it. They also need a bit of margin above or below their output voltage too. A buck/boost DCDC converter is special though, it will automatically switch between lowering or boosting the voltage to achieve its set output voltage, as its input voltage varies. That’s what’s needed for this job.
Parts list
Dealikee Buck Boost Converter DC-DC 8V-40V to 12V 3A 36W Step Down Up Power Supply Regulator
12V 3A output buck/boost switch mode power converter
(Testing this on an oscilloscope, it gives out a steady 12.3V across an input voltage range of 10 to 14V. 12.3V is within +-3% of 12V and will be fine. Turning the power on under load can be a problem though, it oscillates badly. Adding a 1000uF 35V Elect across its input terminals fixes that).
1000uF 35V Electrolytic capacitor
Any standard type will do. Arguably not needed when using with a battery power source (batteries are kinda capacitor like), but using it to be sure the DCDC is happy.
DIXIETREE 5.5mm x 2.1mm DC Socket Wire Lead to 5.0mm x 3.3mm with Centre Pin Connector
The 5.0 x 3.3mm plug is needed for the DDJ-1000 power input.
The 5.5mm x 2.1mm socket is needed to connect the Sounkboks battery
BATTERYBOKS
The Soundboks battery pack (I got a spare free with my Soundboks 3 😊)
(Any high-capacity 12V battery will do)
Results
Works like a dream!
The Soundboks battery is specified as 7.8Ah / 99.84Wh (they chose this as it’s the highest capacity lithium you can take on a plane). Allowing for a bit of inefficiency in the DCDC, that’s going to give up to around 4.9 hours powering time for the DDJ-1000.
Watch out for…
Unplug this adapter from the battery when it’s not in use. Even with the DDJ-1000 power turned off, the DCDC converter will still draw a bit of current. Unplug it from the battery pack to stop it from slowly draining it.
Batteries aren’t happy if they get over-discharged. You can ruin them if you really discharge them badly. Battery-powered products like the Soundboks typically include low battery detect so they can turn themselves off to stop that happening. This little solution doesn’t have that – it will happily carry on drawing power from the Soundboks battery all the way until it’s dead! It’s on you to make sure you don’t over-discharge it.
