I wonder how 22 AWG cable e.g. USB-A to DC power jack with 100 cm length can deliver 3A.
Why am I asking -> Using this calculator (I hope its correct) by entering values 2% drop, 1 meter, 5V, 3A gives me output 16 AWG. And I am looking for right cable to get.
What I need is stable output 5V, 1.7A (top) over 1.5m from power bank which is capable of 5V/3A over USB-A in winter condition. I mean like max -10C (most likely about -2C)
What would you suggest? Power bank has two outputs USB-C/USB-A. I can use both connectors at same time. There is absolutely not possible to use AC/DC power source.
End of cable will be most likely soldered on-board to avoid contact disruption.
Device powered via cable is ESP-32 with some LED strips (outdoor usage with movement)
Best Answer
My suspicion is that they've calculated the 3A capability based on the shortest cable they offer in that listing, which is 50cm. 0.5m of 22 AWG copper with 3A over it has a voltage drop of about 160mV, which is reasonable enough. At one meter, however, it's more like a 320mV, which is probably pushing it a bit if you're regulating 5.0V down to 3.3V with a linear regulator, because that reduces your headroom down from 1.7V to 1.38V.
However, if you know you're only ever going to run it at 1.7A max, you could probably get away with it. In that situation the drop would be more like 180mV (~3.6%) giving you about 4.8V to work with at the device, which should be fine for regulating down to 3.3V using an ESP32 board's onboard LDO.
Keep in mind that these are slightly conservative estimates that don't leave you much wiggle-room for operational variances, so I'd recommend trying to find a slightly thicker cable. Even 20 AWG would provide a marked reduction in losses, getting you closer to 100mV drop over a meter.