So… you want to power a sat-nav or something from the battery?

Here’s what I did…

Forget tapping off the headlight, auxiliary or tail light – they’re all powered directly from the alternator itself. You need a stable 12 volt feed from the battery, preferably switched by the ignition. Ideally you also don’t want to be butchering the wiring loom and you want to find somewhere that’s relatively well shielded from the elements, AND which leaves you with the option of easily removing your connections and restoring the electrical system back to an unmodified original state with next-to no effort as all.Ladies and gentlemen, I believe I have found this holy grail!

Behold the secondary fuses! Right under the left hand side panel, to the right of the fuel pump, we have two 10 amp fuses, aptly designated “Sub Fuse A” and “Sub Fuse B”:

Here they are, covered up all cute and all… They’re of the ‘mini blade’ type. I *think* I worked out what each one sits across in the circuit as well:

Sub Fuse A is looking after the indicators, brake light, horn and instrument cluster tell-tale lights.

Sub Fuse B is responsible for the ignition and fuel injection systems.

I decided to pick on Sub Fuse A. Now then, I recently discovered that you can buy special mini blade piggy-back connectors:

Notice there are two fuse slots in the connector. The lower one is for the original fuse it’s taking the place of, and the other is for the fuse that will protect your new circuit. In my case I will be using a 2 amp fuse for my new circuit, as a sat-nav draws relatively low current.

Here’s a picture of what the fuse box looks like with this connector installed in place of Sub Fuse A:

All that’s left to do is to hook up whatever it is you’re wanting to give some juice to. You could even switch a relay that takes it’s main feed from the battery directly with this connector. That way, you could connect a lot of hungry devices without fear of overloading the circuit. In my case however, I am just adding a sat-nav alone with no plans for anything else, ever (but it will be easy to modify the circuit should I wish to)!

I have modified the connector slightly and crimped on a female bullet connector to the red live wire, getting rid of the default insulated crimp jobbie. This means I can crimp a male bullet connector to whatever I want to connect up and be able to disconnect it easily, should the need arise! I also covered the connection with self-amalgamating tape to keep the elements out. You could use a piece of heat-shrink if you like. After this photo was taken I also wrapped self-amalgamating tape around the actual fuse holder part of the connector because if you look closely, you’ll see that the construction of it means that there is a gap exposing the terminals inside.

You might also want to give the entire assembly a covering of silicone grease or ACF-50 as it’s now a bit more exposed than before. It’s messy but won’t hurt it in the slightest, in fact, you’d be doing it a favour.

Now all that was left to do was to connect the negative wire from the sat-nav to the battery. So I crimped on a nice round connector and screwed it on to the battery’s negative terminal. Also put some grease over the terminal for good measure, to protect against corrosion, especially during winter.

As for routing your new wiring, just follow the loom/guides in the bike. I’ll probably add cable ties to secure it a little better but it’s absolutely fine as it is, in my opinion.

All done! 🙂


10 thoughts on “So… you want to power a sat-nav or something from the battery?

  1. Hello friend, nice work there,
    So, as you know i have powered my things trough the rear brake, if i had understand right you have feed the GPS trough the fuses near the fuel pump right?


      • ok, thank you for the answer.
        I’ll maintain my circuit, although i need to ad another relay so the alarm won’t work while the engine is running.

    • Hey Joshua,

      On my 2005 YBR, the rear/brake light uses spade terminals, and you can get hold of piggy-back spade connectors to attach to your accessory wires (or relay if you are hooking up one or many heavy current drawing devices) – no need to splice into the bike’s wiring loom if you do it this way. If you’re unsure of which wire is which (there are three – an earth, one for the brake light live, and the other for the tail light live) just use a multimeter and find the tail light live as that’s the one you want to tap off from. Take off the rear cowling for easier access to it all. I won’t go into any more detail because this is a CBF125 resource rather than one for the YBR.

  2. Thanks so much for this, saved me from cutting into to the wiring loom, which was something I really did not want to do to fit my heated grips, just ordered a piggyback and a relay.

  3. Do you think the battery/alternator is man enough to power a set of heated grips? I have zero electrical expertise so am slightly worried that if I fit a set I’m going to drain the battery on my first trip out.

  4. Pingback: Undocumented spare +12V switched connection! | CBF125 Rider

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