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Answers to this question Is power consumed from battery to run the phone when charging? explain how charging while phone is in use does both - charging the battery and powering the on going activities.

My question is different — Can I stop charging the battery but use the connected power for ongoing activities?

Why do I want to do this?

and

  • at the same time use the charging power to keep running the phone without any heat stress on battery, thus extending battery life.

  • Also the battery is not drained, enabling me to use the phone for longer time without charging

Edit : I am not looking for dedicated cables or hardware that can possibly do this

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    Note that no matter what the UI says, in general case the charger does not have enough power to meet the peak phone demands. That's why most phones and tablets (and also some laptops) cannot be started without a battery. Depending on how you acheive your "battery idle" state, you will either get quick discharge-charge-idle transitions (defeating the initial idea), or slowly depleting battery.
    – fraxinus
    Commented Apr 10, 2020 at 15:31
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    @fraxinus 1.As mentioned in the answer the effective power supplied to run the phone is that of USB 2. quick discharge-charge-idle transitions do not happen in this implementation. I have run the device for 4 hours max in this condition with only one percent drop (watching you tube) - this point is also briefly mentioned in the answer
    – beeshyams
    Commented Apr 10, 2020 at 15:37
  • This has always been possible AFAIK using a Factory Cable. You can either make a Factory Cable from an existing USB cable, or buy a Factory Cable Adapter that does the same (Team Blackhat used to sell the adapters, but I don't believe they still do). A Factory Cable, or Factory Cable Adapter, supplies power to the device, entirely bypassing the battery
    – JW0914
    Commented Apr 10, 2020 at 23:37
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    I asked a similar question: Can phones/tablets avoid charging from USB power?
    – Nayuki
    Commented Apr 11, 2020 at 17:40
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    OP, or @JW0914 Where can I read more about such a "Factory Cable Adapter"? Is it an industry wide standard? How does it work? Does anyone still make them? Do for example modern Samsung phones support this trick? ACC app's "battery idle mode" is not supported by samsung kernels it seems, that much I know.
    – Spectraljump
    Commented May 11, 2021 at 10:13

2 Answers 2

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Yes, it's possible if your device is rooted running Advanced Charging Controller-Acc Magisk module and device kernel supports (see currently known list at the end of answer. For more join telegram )

  • Battery Idle Mode: To activate this feature at a user defined battery level.

And/Or

  • Custom Charging Voltage Limits: Activates this feature at a user defined voltage level. This method is superior to first method since granular voltage control is possible Keep in mind that battery charge level is not an accurate indication of voltage. Kernels that support this, include support for first mode too.

  • Custom Max Charging Current:

  • ** Idle mode for selected apps:** In a recent update users can select apps, which when running trigger idle mode, a very useful feature while watching YouTube, playing games, etc.

First step is to configure charging to be stopped at a safe level, in my case, 75%, using the Acc module

Next step is to use the charging power to run the phone only

How does it work?

In either methods (battery idle mode or Voltage/Current based) , the charger is fooled into "believing" temperature conditions aren't good for charging (either the reported battery temperature is too high or too low, so battery charging is discontinued as a safety precaution).

That means the device is drawing power from the external power supply alone - which is exactly what we wanted! And the battery doesn't get drained because it is not being used (of course over a long period of time it would drop a percentage point. As an example I used the device to surf for 4 hours, mostly YouTube videos and lost just 1% of battery).

On my OnePlus 7, battery idle mode is supported by Kirisakura kernel. Interestingly, beta versions of stock ROM have this feature in stock kernel but one doesn't know if it makes it to next stable version (Edit : Stock kernel on 10.3.2 supports idle battery mode as verified by me)

When this feature is running, a low USB equivalent power is fed to the phone and conventional charging indicators show charging with zero power. Note that the second screenshot (Ampere app) shows "not charging" and no word about discharging, so the battery is at status quo. Normally, such apps show a binary status, either charging or discharging. Here, you see the difference

enter image description here

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This screenshot below is from ACCA (Acc App, optional companion app of Acc Magisk module ) which offers all the command line options (believe me, a ton of them) in a user friendly GUI. Edit: ACCA is not being developed for more than 2 years now and using this is likely to cause severe problems. Instead use CLI (Termux) or a MacroDroid (automation app) based front end,developed by an avid user. It shows battery charging idle mode at 75%

enter image description here

Edit: The list below is very old (and not updated), practically all phones are supported now (except for kernels that do not support idle mode). The developer is very active and I would recommend joining the Telegram Channel to be abreast of the latest.

Support Battery Idle Mode

  • Asus Zenfone Max Pro M1
  • Essential Phone
  • Lenovo K5 Pro L38041 (kunlun)
  • Motorola Moto G4 Play
  • OnePlus 7/Pro
  • Xiaomi Redmi 3 (ido)
  • Xiami Redmi Note 8
  • Pixel 4a on Android 11 (not initially but in subsequent updates) and Android 12.

Support Custom Max Charging Voltage

  • Essential Phone
  • Lenovo K5 Pro L38041 (kunlun)
  • Xiami Redmi Note 8

Support Custom Max Charging Current: Some phones support this as well ...

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  • Note : The Magisk module is being continuously being developed, so it's best to use the XDA thread or the Telegram channel
    – beeshyams
    Commented Apr 12, 2020 at 16:53
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    According to the xda thread (and based on lack of dev activity since nov 2020) it seems the project is dead, and indeed the client app at least seems to be buggy on new devices. I don't know of any alternatives that prioritize bypassed cable power over battery, and would gladly buy a "Factory Cable Adapter" but I can't find anything on either fronts.
    – Spectraljump
    Commented May 11, 2021 at 10:09
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    @Spectraljump development has re-started a few months ago
    – beeshyams
    Commented Nov 13, 2021 at 12:57
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For completeness, I want to add my solution. I have been using a tablet as a control panel for home automation. The first one died, with a swollen battery that made the screen detach from the case.

Samsung repaired it, but didn't tell me the cause. I realised it later. So I now use the home automation to disconnect power to it for 4 hours a day.

A simpler soltion would be put a mechanical or electronic timer to do the same.

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