Can Android app repair battery's bad cell? I know this was covered in a different post, but I've been wondering how this app can actually make a difference in battery life. I've tried many of these, and "Repair Battery Life" is the only one that seemed to help. I understand that, like everything Android/Linux, the battery is a file, and that file can be manipulated to show whatever percent (a bad ROM/Kernel combination once showed -%1078663).

I've got a Galaxy S3 (i747). There are times when my phone will sit charging for an hour or so, yet only have 10%-15% charged. When that happens, I run this app, and it manages to find 2 or 3 "bad cells". After fixing them, my phone then charges much quicker, and battery life is back to normal. I was under the impression the only thing you can do to impact the apparent battery life was recalibration, which I'm not convinced matters. It's also worth mentioning that I've installed this app several times after wiping my phone and flashing a ROM, and it had upgraded itself to the Pro version with absolutely no input from me. The first time I ever used this, it upgraded itself. Next couple times I reinstalled it, it didn't upgrade. This past time, it did - again, for no reason. So, I'm really confused, here, because I don't understand why the app randomly upgrades, and I still can't figure out how this app "fixes" my battery.

It's also worth mentioning that every so often, it "finds" new "bad cells" randomly. And every time I have it "fix" the problems, well, it actually seems to fix the battery issue. Doesn't make sense to me. 

However, my phone has been through some semi-traumatic events in it's life (well, in my possession). It has fallen out of my pocket while crossing a road, and after I realized it was gone, I retrieved it. Luckily, it had been face-down. It had been run over a few times, and it cost me my rear camera, which still worked for a few months but finally crapped out entirely (any camera app crashes almost immediately). It has also been victim to an unexpected dip in a pitcher of water for about 10 seconds, while playing music and downloading, so it was also running a bit hot. After letting it dry overnight on the air vent, it worked. Mostly. About 90% of my touches didn't register, and so I figured I'd have to either replace the digitizer or just get a new phone. Later that day, it finally started working again, perfectly. I did read, however, that people who had the same luck with their screens were complaining that after about 6 months or so, their phone would behave erratically and eventually die completely. 

So, is this app actually making good on its claim, or does it seem like my phone is just suffering a weird, periodic combination of events that only allow "Repair Battery Life" to right them? I've seen this app report "bad cells" on a brand new Note 5, and read that someone had "bad cells" on an emulated copy of Android. I mean, right there should be the obvious BS-flag, but still. It does seem to do something beneficial in my experience.
It's a scam. Android app cannot access physical battery directly.
The battery file is just an interface for Android with value provided by the battery's sensor. Again, a sensor only reads data; it cannot write/modify anything.
An article on Android Police explained this very well,

Battery not working correctly? Well, just defrag it! It's all so obvious now. No, but really, there's an app in the Play Store that claims to repair your battery and basically looks like a hard drive defrag program.
So here's what the app supposedly does—Battery Life Repair analyzes your battery &quot;data cells&quot; to see which ones are under-performing (okay, whatever). Then it magically fixes them and improves your battery life by unrealistically huge margins.
Anyone who knows much about technology will immediately be suspicious of this app's claims. If it were possible to wave a magic wand over your battery and fix the &quot;data cells,&quot; you can be sure the engineers who made your phone would have built that into the software.
The fact that so many real people (and probably some bots) are praising this app is a tribute to confirmation bias and the power of the placebo effect. Consider this a cautionary tale.

(Emphasized added)
Also, looking on similar app's permission,


modify or delete the contents of your USB storage
read the contents of your USB storage
view Wi-Fi connections
full network access
view network connections


It's doubtful for this app to really be able to access the battery, compared to other reputable optimization apps, like Greenify (this app doesn't access the battery directly either, but it can kill apps that may drain much power, improving the battery life in a sense).
Disclaimer: I don't have any affiliation with the offending app nor Greenify