USB cables differ greatly with regards to their resistance. Too big a resistance can prevent devices from working or make them charge slowly. So, what about USB-C cables?
I took my power bank, some USB-C cables, two USB-PD trigger PCBs, a multimeter and a small electronic load, put all of them together and devices a small test setup: First, measure the open circuit voltage at the end of the cable. Then, put 2.5 A of current through it and measure again. The baseline is a USB-PD trigger that is directly connected to the power bank (“no cable”). That module is larger than the other and thus potentially suffers from more voltage droop. Thus, it is a fine baseline. The other, small module will be attached to the USB-C cables. The column “relative power lost” describes how much power is lost in the cable, compared to what the power supply theoretically outputs (open circuit voltage * 2.5 A). The “no cable” case shows which amount is lost in the power bank, the connectors and the USB-PD adaptor.
|Type||Length (m)||Voltage w/o load (V)||Voltage w/ 2.5 A load (V)||ΔV (V)||ΔV, cable only (V)||Resistance (Ω)||specific resistance (Ω/m)||Dissipated power (W)||Relative power lost (%)|
|??? thick plug||1.6||20.07||19.25||0.82||0.63||0.252||0.1575||1.575||3.14%|
It’s apparent that the most expensive cable (Anker PowerLine+) performs worst: Its specific resistance is 139% worse than the Baseus (2m) and 16% worse than some random no-name cable (“thick plug”, 1.6m) that I had lying around. Put into user-centric terms: If I attach my phone to the Anker cable, it would charge 2.6% slower than with the Baseus cable or 1.4% slower than if I would use the no-name cable. I didn’t expect this and I’ll keep an eye on those Baseus cables. They are totally worth their 2 €!