Phone charging vs phone powering

by Mastercore   Last Updated October 13, 2019 10:01 AM

I have a simple question: When I plug in my phone while it is on to charge, am I:

  1. Charging the battery only, phone is being powered only by the battery
  2. I am powering my phone and only charging the battery with excess current available from the charger (e.g 2.1amp USB charger, Phone drawing 0.4amp at current use, battery is being charged at remaining 1.7amp)

Another way to phrase the question potentially could be: If I were to open my phone an remove the battery, could I still power it by the USB port?

Background: I have a use case - Enduro riding and using my android phone for my main electronic navigation. I have a USB charger on my bike (1.0 amp and 2.1 amp port) but seems when I plug in my phone to navigate, despite getting 2.1amp, the battery is still slowly draining. What is the matter here?

I have toyed with the idea of taking an old phone and flashing it with a base android ROM and only installing my navigation app, remove the battery (weight), only powering by USB, and basically making it a nav device only.

If all power from the USB has to pass through the battery (charging) to power the phone, and you only use it tethered to a USB charger, what happens when the battery is thoroughly finished?

I look forward to all your comments Thanks

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