Repurpose Qi Switch for behind dash usb

Hey!

I’m going to be installing a USB behind my dash. I was thinking about wiring my usb to the Qi switch for the on/off toggle and for its power. The plan is to make the charging pad non functional. The UBS has 2 wires. I’m little confused where those wires would connect because the Qi pad has more than 2 wires. Your guidance would be appreciated!

 

If you figure this out, I'll bet you could create a kit for this and start selling it.

 

that’s a big IF!

 

Or make it so you can power up a Valentine One Radar detector

 

The USB should have 4 wires. 2 for power and 2 for communication. The Qi charger is not connected to the USB and not part of it.

 

You could use a cigarette adapter with external wires and connect those to the power and ground wires of the switch. However, you'd be limited to whatever current that switch supports. I think the OEM switches only do 3A.

But if you use a relay you can tap into a higher rated fuse and use the switch to actuate the relay.

 

The USB has 2

$10 E-Outstanding 1PC DC Converter Module 12V to 5V 3A 15W Regulator Step Down Car Power Converter with Double USB Cable DC Buck Converter

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The goal is to take the power from the Qi charger to power the new usb. I’d like to repurpose the Qi switch for turning the usb on/off.

 

I wouldn’t be pulling power from the switch. I’d be pulling power from the Qi’s power source.

 

Right on. Don't know how much current that draws but I know it didn't do a great job at charging my phone; I was showing about 500mA on average but that could be a limitation of the charger rather than the circuit it uses.

 

I can’t remember where because I’ve been googling all evening, but I saw that it’s 12v. I think the charger isn’t very good.

 

All vehicle circuits are 12v, with some exceptions like the dimmer circuit that are negatively grounded. Unless I'm mistaken.

 

Not entirely true. Circuits can be stepped down. USB for example is 5v.

 

thanks for the diagram. I should have included in original post. I had found this, but I’m just not really sure what wires go where.

 

Even if it's ground switched, it could still be 12v.

 

@caribe makaira the schematic guru, what say you?

 

Looks like the switch is just an input to the wireless charger module. You should be able to rework that to switch a relay that will turn a USB charger on and off.

 

Right, but isn't the dimmer circuit less than 12v based on the dimming setting? Also forgot that USB circuits are 5v.

 

it doesn’t look like the full power to the charging pad goes through the switch, it’s using the switch to tell it to turn on, then gets full power from a different circuit. So I’d be very dubious of running your USB PSU directly through that switch. You really should use a relay.
If you add a relay, then run the coil of the relay blue wire, and the other side to ground, then the switch / contact side of the relay to the green wire, and the other side to the +12 on your usb psu. That should do it.

 

This seems like a whole lot of work when you could just replace the cig lighter with a dual usb plug or tap into the power for it and add ports wherever you want. I don’t see any point in having a switch for it..