This is what I need: enter image description here

What's the best way to achieve this without damaging my car's audio?

I want to connect my iPhone to my car's audio and charge it at up to 4.2A iPhone will draw up to 2A instead of 500mA.

Or would it be easier to use a USB hub with external power source, such as 2A?

Unless it's possible to "bump up" the car's audio current to more than 500mA.

  • \$\begingroup\$ Why not use two seperate plugs. One to charge the phone, one to do wheatever you want to do with the radio? If you want to charge, plug it into the charge port. \$\endgroup\$ – Hennes Jun 8 '17 at 20:59

Simply - you can't. Let's assume both the car audio and the charger start at the same time when you turn the ignition key. It will never happen, but let's think it does. When your phone handshakes with your car audio's USB it will tell it that it is a USB data port and the phone will internally limit its consumption to up to 500mA as per standard. So no matter your charger can supply 4A, your phone will draw only 500mA.

There are some docking stations that can do the trick.

Powered USB hub will not help either. It will just reduce the consumption from your car audio, but the phone will still draw 500mA from the charger.

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  • \$\begingroup\$ Is there really now way to trick my iPhone to draw power from the charger? How about parallel switching using aforementioned LTC4412 chip? Problem is that 500mA is not enough when using 2 metre USB cable :/. Let alone charging when using satnav on the phone. \$\endgroup\$ – Maciek Jun 8 '17 at 18:42
  • \$\begingroup\$ No. It is done by a special USB communication chip, which can be seen in docking stations. \$\endgroup\$ – Todor Simeonov Jun 8 '17 at 18:53
  • \$\begingroup\$ How about 'bumping up' the current on the car's audio? Or maybe OTG cable? Or modifying (jailbroken) iOS to draw more regardless? \$\endgroup\$ – Maciek Jun 8 '17 at 19:07
  • \$\begingroup\$ @Maciek: 1 - no, 2 - no, 3 - not sure, but I doubt you'll have any success. \$\endgroup\$ – Todor Simeonov Jun 8 '17 at 19:47

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