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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

  • 2
    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 Apr 10 at 15:31
  • 1
    @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 Apr 10 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 Apr 10 at 23:37
  • @JW0914. I have read of such cables but they won't meet the requirements of bullet point 1 in the question isn't it? That is of charging till user wants to. Perhaps you are referring to the title and mailing this observation, in which case I agree title is misleading, sorry, didn't frame that well in an effort to keep it short. Thanks for your observations – beeshyams Apr 11 at 0:57
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    I asked a similar question: superuser.com/questions/1365704/… – Nayuki Apr 11 at 17:40
22

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)

  • 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.

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 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

enter image description here

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. It shows battery charging idle mode at 75%

enter image description here


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

Support Custom Max Charging Voltage

  • Essential Phone
  • Lenovo K5 Pro L38041 (kunlun)
  • Xiami Redmi Note 8 ...
| improve this answer | |
  • Note : The Magisk module is being continuously being developed, so it's best to use the XDA thread or the Telegram channel – beeshyams Apr 12 at 16:53

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