Wow, thanks for doing that.

I can add that I did probe the mini-USB adapter and the data pins D- and D+ do pass through to the 30-pin connector, pins 27 and 29. So I do see the appropriate signaling voltages for charger current capacity, at least to where the 30-pin mini-USB adapter feeds into the 30-pin extension cable.

Since all of this gear is trapped inside my car dashboard it is no fun exposing each connection point. Even the 0.2m adapter cable has the 30-pin end hidden inside the dash.

The USB car charger I have in there is a ZAGG dual outlet, and both sockets have the 2 amp (10 watt) data signal voltages. When I plug my iPad or iPhone into the other outlet I do get close to ten watts charge power. Both ports are the same and swapping ports makes no difference to the results. I am only testing with one charger port at a time, no dual loads.

I am using a DROK OLED USB 3.0 Meter to monitor voltage, current and power flow into the load device.

It is unclear to me whether the monolithic Lightning to 30-pin adapter is electronically the same as the version with the short flexible cable.

I just realized I did not (because it is buried in the dash) verify that the USB signaling pins (27 and 29) within the 30-pin extension cable actually extend to the far end of said cable.

The iPhone was below 80% charge during my testing, and the Drok USB tester is quite useful for this sort of thing.

Side note: I do wish Apple would expose the charge rate on the actual iOS device, would make charger validation and checking so much easier. That little lightning bolt battery icon doesn't reveal enough.