I'm working on a project using LEGO Boost that I'd like to keep it powered on for a long period of time. The Boost hub itself does not move, so I'd like to power it using an AC adapter instead of using batteries to save myself time and money changing them out.

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This isn't possible out of the box, and there aren't currently any adapters available from TLG to support this as far as I know. I did come up with a modification to make this possible, though.

My goal was to allow me to modify the hub to receive external power in a way that did not damage the hub and would be totally reversible. Ideally, I wanted a solution that could also still work with batteries without having to undo the modifications.

I started by removing the contacts that connect the battery holder to the main hub. These could probably be left in, but the next step is to solder wires to them, and I wanted to make sure I didn't melt any plastic.

Hub with battery contacts removed

Now we solder on some wires. I chose to use Dupont connectors here so that I would have a very small and detachable connection.

Battery connector with wire

Now we put the battery terminals back.

Battery box with wires

A nice feature of this setup is that in its current state, batteries can be installed and the box still fits perfectly inside the hub.

Hub with batteries

From here, you could probably get away with running wires directly out of the hub if you didn't mind it not closing completely. If you didn't mind damaging the hub, you could also cut or drill a small notch at the bottom for the wires. I opted to run the wires out of some holes that already exist in the bottom of the hub.

Routing wires top

Routing wires bottom

From there, it's simply a matter of connecting the two wires to a suitable 9V supply. If you attempt this yourself, it is critical to match the voltage and polarity of the batteries, or you risk damaging your hub.

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