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Phone charging vs phone powering

Discussion in 'Android Devices' started by Alex Lototzky, Oct 13, 2019.

  1. Alex Lototzky

    Alex Lototzky Lurker
    Thread Starter

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

    Charging the battery only, phone is being powered only by the battery
    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


  2. Best Answer:
    Post #3 by Hadron, Oct 13, 2019 (1 points)
  3. Alex Lototzky

    Alex Lototzky Lurker
    Thread Starter


    I have 2 old phones in my draw, both of which you can remove the battery. I did a test to see if I could power the phones only with cable, no battery. Neither worked.
    Even though the batteries are old, if I put the batteries in, both phones start up.
    Of note, the battery packs both are labeled as being ~3.7v
    I take that as meaning that the phone must regulate the incoming 5v from the USB down to 3.7v for charging, and the phone itself runs off of 3.7v. Meaning the battery acts as a voltage regulator dropping the cable incoming voltage from 5 down to 3.7v.

    I wonder if I were to take the battery out and in the void left, install a voltage regulation chip that regulates the 5 down to 3.7 volts.
    Has anyone done anything like this?
  4. Hadron

    Hadron Smoke me a kipper...
    VIP Member

    You are only charging the battery. The phone always runs on battery, even when plugged in.
    (At least that's been the case for every device I've owned).

    As for your battery slowly decreasing when in use, there is nothing the matter there. You are simply using more power than you are supplying. Navigation uses GPS continuously, is probably using a network connection, and is likely to be running the screen at high brightness (as you are outdoors), so it will use a lot of power.

    And as for what happens when the battery is thoroughly finished and eventually fails, you replace it or you replace the device.
    tube517 and Dannydet like this.
  5. Dannydet

    Dannydet Extreme Android User

    What Hadron said...

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