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So I recently bought a new radio head to substitute my older one, everything went smooth and I could install it without problems. The new one has 2 USB ports, which I am going to pass-through to my cigarettes-lighter-dashboard to have a couple of "OEM-looking" USB ports.
I would like to have the possibility of plugging 2 music sources and/or charge them if they are mobile phones.

Now, since the radio head supports DAB+, I'd have to buy an adapter that would make use of one of those 2 USB, which means that in order to have 2 USB ports in my dashboard, I'd have to split one of the two USB provided by the radio head.

The power output could be not enough to power 2 phones at this point. I would still have the cigarettes-lighter power outlet, but I would like to avoid swapping plugs to an cig.lighter-to-USB adapter only to charge a phone.

Is there any way I can get 3 USB from the 2 provided by the radio head, without losing any power?

  • The power on both ports will be less then without splicing it. If this is or is not enough to power your phone(s) im not sure. If i were you i would pull another wire for the second USB port. – Granny Nov 13 '17 at 8:20
  • If the two usb from the radio cannot power what you need, then provide the power to those ports from a different source and just allow the data to be connected to the radio's 2 ports. From memory, the outer two connectors of the 4 are power, the inner 2 are data, but CHECK... – Solar Mike Nov 13 '17 at 8:55
  • @Granny I'm pretty sure that there won't be enough power, especially if on one phone I'd be using WiFi and bluetooth for example. Consider that I would want to use one of the radio's USB to plug a DAB+ module... – Noldor130884 Nov 13 '17 at 9:35
  • @SolarMike Do you know any device that powers up/amplifies a USB splicer, that can be connected to the cigarette lighter power socket? – Noldor130884 Nov 13 '17 at 9:37
  • e-bay does 4 way / 7 way usb expanders etc for computers which may or may not connect to mains power... I found one that is powered from the mains so will charge stuff without the computer connected : made by Kensington.. have a search - you may find one you can re-power from 12v... – Solar Mike Nov 13 '17 at 9:47
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Anything that you do to split or boost the power on a USB line will most likely cause a phone to stop considering it a data channel. When it comes to the computer connectivity lines on USB, devices are much pickier than they are with the power lines. Also, you cannot have 2 different peripherals using the same data lines without using a hub (or similar circuit), and hubs (in many cases) aren't compatible with the source device (in this case your head unit) and/or the peripheral.

I would say that the best way to do this is one of these 2 options:

  1. Use the 2 USB lines provided by the head unit to connect as data channels, then add a 3rd that handles power only which is powered from your 12 VDC power (cigarette circuit is a good option).
  2. Install a 3-port face, and bury a hub like this in the dash. then connect 1 of the USB's from the head to your USB plate, and run the other to the hub. Then run 2 from the hub to the remaining plate slots.

Like I said above though, depending on the source and peripherals, a hub may not be accepted as a valid data line. Therefore your only true data line would be the one that goes straight from the head to the plate. Just like plugging your phone into a wall charger, it doesn't ask (with iphones) if you want to trust the device, because it doesn't consider it a data device.

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