What is Miscellaneous Battery Drain? How to Fix it?

Seeing Miscellaneous Battery Drain under Battery Stats in Settings? Here's what it means and how you can fix it.

Miscellaneous Battery Drain on Android

Miscellaneous Battery Drain in Battery Stats is Annoying. Learn how to fix it

If you have rooted and flashed a Custom ROM on your Android, then most probably you might have faced battery drain issue.  On going to the Battery option in Settings app, you might have found that “Miscellaneous” process is eating a lot of your Battery. This is called Misc / Miscellaneous Battery Drain. You might have noticed that, below is the image for better understanding:

miscellaneous battery drainHere we have presented a detailed research on what exactly is miscellaneous battery drain and how to fix it.

First of all, it is important to know that there is no actual “Drain”. The battery stats displayed on your screen are guessed calculations, never accurate.

Basic version

Here’s how battery stats work.

In Android, there is a file. It lists “power consumption” for certain things.

For instance,
Wi-Fi disconnected = 4mA
Wi-Fi connected = 10mA

That means, if your phone is connected to Wi-Fi for 10 hours, it calculates that 10 hours @ 10mA = X% of battery used. But what if you are at far distance from your router and in reality you device is using at 20mA because of the weak signal. This variation is not accounted in the file. There is no “Wi-Fi connected but user is in bedroom = 20mA” entry in the file.

In reality, battery stats do not have any direct or indirect link to the physical battery of your device. It’s purely a guess. Battery stats knows how much battery has been used and using its magic file, makes an educated guess at how much % battery has been used by each thing.

Also See: How to Root Vivo Devices?

So your battery has depleted by 50%. 25% is Wi-Fi connected at 10mA. But your Wi-Fi was actually using 20mA because of distance. Battery stats do not account know this. So you actually have 25% missing in battery stats. That’s where “Miscellaneous Battery Drain” created for. To show that there was a difference between battery stats guess and actual battery use from the battery.

The above example also applies to all other factors like screen brightness, cell signal, CPU usage etc. The file knows very little; battery stats are highly inaccurate.

Google has removed “miscellaneous” tab from the stock ROMs because normal people don’t understand, calling it a Wi-Fi bug. However, it still exists in AOSP.

Advanced version

How battery stats work

The Battery stats UI shows the percentage of battery that device elements are responsible for using, which is based on a couple of things.

1./data/system/batterystats.bin
2./system/frameworks/frameworks-res.apk/res/xml/power_profile.xml

These things contribute in the following way:

1.From the moment Android detects a close-to-full charge, batterystats.bin records how long the device elements are running
3.This XML file is where the information about how much power, each device element “uses”

The battery stats UI looks at batterystats.bin to see how long each element has been running (and in what state) since the last charge, applies the value (in mV) for each element stored in power_profiles.xml and comes up with a calculation of the % of battery each element is using.

It simply knows the total mV used by adding up all the element values and the time in state to work out the percentages.

Why does Miscellaneous show on some ROMs and not on others:

There was time back when people were frustrated by “Wi-Fi Bug” and started reporting it to Google. This is when Google got fed up and hide Misc option in Stock ROMs. None of the stock ROMs on Nexus show Miscellaneous anymore.

However, a miscellaneous option is still available in AOSP code and developers making Custom ROMs from AOSP might not hide it. So ultimately, some custom ROMs like SlimROMs have hidden Misc option while other still have it.

Conclusion

Actually, there is no such thing as “Miscellaneous bug” or a “Wi-Fi bug”; in fact, it never was. It was just people getting hyper about their Miscellaneous Battery Drain which was displayed on the Battery Stats page, which was of course not reliable at all.

Concluding, if you are one of those who have installed a custom ROM and seeing Miscellaneous Battery usage to 30-40-50%, there’s no need to panic. Instead, try to monitor how long your mobile works after a full charge and then compare the usage with what it was before installing the Custom ROM. If the usage hours are less than earlier, you need to change the ROM. I am pretty sure that you won’t need to do that.

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