2021 Release of the Black Box Module

One of Purpose Built Moto’s first and most popular products, our Motorcycle Control Relay lovingly named the “Black Box” has undergone some major and handy changes. Our last iteration sold out in a flash, which let us know we were on the right track. From the outset I wanted to give people a less complex alternative to the Motogadget M-unit. Our hundreds of happy customers make me think we’ve succeeded. The most common compliment we get about this unit is about its simple, no fuss install and operation. We’ve included everything you need, and nothing you don’t.

There’s always room for improvement though, so in this blog I’ll take you through the differences and similarities between our new electronics control box, and explain just why we made it that way.

Improvements to the new Black Box Module:

  • Size– It’s tiny! Measuring at L 40mm x W 35mm x H 26mm
  • 6V and 12V operation – This ones for our Vintage Dirt Bike friends
  • Better fuse – In built mini blade fuse changed from the tube fuse in V3
  • High quality Internals – Using German Engineered components for a better quality Circuit board.
  • Accessories Kit – An optional kit for your Black box to make sure you have everything you need to get your bike humming!

So let’s break down the improvements on our redesigned electronics control module. Starting with the biggest (smallest) change.

Size – Size matters, no matter what your girlfriend says. Through smart design and using higher quality components we’ve been able to halve the size of our new black box motorcycle control relay module. Usually on a café racer or scrambler build you have a bit of room for your electronic control box, but as I’ve started to build more bare bones choppers and Bobbers something I quickly realised was there’s no room for anything!

The Goal here was to make the Black box control relay module small enough to be mounted in the tunnel of your tank. With the new sizing of the Black Box, we’ve achieved that. This thing is small enough to mount in a headlight bucket if you want to!

For a bit of comparison here are the dimensions of a few options in motorcycle electronics control:

Black Box V3 – L90 x W40 x H25mm

Black Box V4 – L 40mm x W 35mm x H 26mm

Motogadget M-unit – L101 x W60 x H30 mm

6V and 12V Operation – Sometimes a 12V conversion just isn’t worth it, and now you can use the Purpose Built Moto Black Box on your vintage off roader or street bike while keeping your 6V system.

As soon as the Black Box hit shelves, our customers were asking for a 6V version. I wanted these guys to feel included so we worked hard to make sure our Black box works in both voltage ranges. With a voltage range of between 5-16VDC to make sure your bike will be flashing and beeping under any normal operating circumstances.

Upgraded Circuit Protection – Having a physical fuse is a personal preference of an integrated Circuit breaker. An auto reset breaker tends to let you ignore and intermittent problem, which is rarely a good thing. Motorcycles have issues, that’s part of the charm of a classic or custom bike. Our V3 Black box control relay module used a ceramic tube fuse, easy to find for someone who knows what they’re looking for. An oversight on my part in the initial design has been addressed in our latest update.

Now using a mini blade fuse for circuit protecting has 2 major advantages

  1. No more faults due to vibration. Tube fuses can succumb to heavy vibration, especially glass ones. Blade fuses are far more physically robust.
  2. Easy replacement. Had a fault out on a ride but forgot to carry a spare? Anyone with a stock motorcycle or car will have one of these fuses. Making sure you’re never caught in a jam.

High Quality Internals – Experience pays with product development. And to ensure the longevity of our products was better than ever before we went shopping. Using German engineered components for our switching and control circuits.

The black box has always been a tough little unit, ,my first ever prototype is still running around on a bike in the Gold Coast, but we had the opportunity to make it better so we did. With a number of solid state components, and an upgraded kill switch circuit the latest control box is better than ever.

Accessories Kit – This one again comes down to experience. When I wire a bike, I have a whole motorcycle shop at my disposal with any and every part I need. Not all of you have the same. Realising that now we’ve put together a kit of a few essential accessories. Including a terminal strip and 2 micro blade fuse holders.

This gear we use on all of our bikes, keeping things easily serviceable, tidy and most of all discreet.
If you’re doing a total re-wire this kit will pay dividends in your wiring layout and termination. All you need is the cables to connect it all and you’re ready to get to work.

Installing your Black Box Lighting Control Relay Module

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We run this gear on all our offroad and ADV bikes.
including the ones we ride for Wide Of The Mark.
they stand up to whatever you can throw at them.

Check it out here;



How weather element proof is the Black Box Unit and the momentary switches you sell with it? It is possible to have heat, rain, freezing temps, and snow here in the Black Hills area of South Dakota in a single day.

chad m davis

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Purpose Built Moto is home for unique custom motorcycle builds. We offer a unique motorcycle customizing experience in the heart of the Gold Coast.