USB devices reduce their current consumption with decreasing voltage. This is because the maximum current ability of a dumb USB charger is unknown to the device and the charger signals reaching the current limit by lowering the voltage.
As a side effect the current consumption of the device (and therefore the charge speed) also decreases with increasing cable length. This is the problem I'd like to solve.
Since the USB cable has 4 wires it would be easy to modify it, so that I can sense the voltage at the end of the cable, just a few mm before the connector.
Searching for a solution I found LDOs (example: LP3856) that have an additional sense pin.
Q1: Would such an LDO solve my problem?
I guess that it would only compensate 50% of the voltage drop since half of the drop happens on the GND wire? (Q2)
Q3: Most adjustable linear regulators have an V_adj input. Could I "misuse" that input as sense pin simply by connecting one end of the voltage divider to my sense wire?
Q4: Many boost/buck converters also have some external circutry for feedback. Would the trick from Q3 work there also?
Q5: Any other suggestions to solve my problem?