Why is my battery life draining so fast?

[Android Central Question]

Bought a second hand LG G2 a few months ago.
It works perfectly except for one thing; the battery life is abysmal and it also becomes very hot at the back - it lasts for at most 3 hours on a full charge.
I have location, sync, NFC, bluetooth, data and LED off, screen brightness is on 38% and I am using the Battery Doctor app.
Performing a soft reset did not help, and neither did performing a factory reset.
The phone is running Android KitKat 4.4.2. I rarely ever use it at all due to its short battery life. I just don't understand what's wrong with it.
Could anyone help me with this?

 

[Rukbat]

First, get rid of Battery Doctor (and anything else developed by Cheetah Mobile - they demonstrate a superb lack of knowledge of how Android works).

Second, have you thought that by this time the battery may be shot? If it's the original one, it's 4-1/2 years old so, even if it's been treated properly since it was new (and the odds are that it wasn't - most cellphone batteries aren't), it's almost 2 years past the time when you'd expect it to need to be replaced.

 

[androiduserr55]

First, get rid of Battery Doctor (and anything else developed by Cheetah Mobile - they demonstrate a superb lack of knowledge of how Android works).

Second, have you thought that by this time the battery may be shot? If it's the original one, it's 4-1/2 years old so, even if it's been treated properly since it was new (and the odds are that it wasn't - most cellphone batteries aren't), it's almost 2 years past the time when you'd expect it to need to be replaced.

The problem is the same with/without battery doctor.
I'll try replacing the battery; problem is LG have made it damned difficult to do so.
Thanks.

 

[Rukbat]

It's not supposed to be replaceable by the user, and you're going to find more and more of that. (The more they can make the battery in odd shapes, and you can do that with today's batteries, the less access we're going to get to them, because eventually it's going to take disassembling the whole phone to get the battery out. We're just lucky that they've stuck to rectangular batteries in most phones so far.)

 

[Mooncatt]

I'm also thinking it's the battery, and it's unlikely you'll find any really good ones even if could source some. Given the age of the phone, any "new" batteries have likely been sitting on a warehouse shelf for a couple years and already degrading. You also have to consider that modern apps on that phone are going to push it to the limit and beyond. Assuming they run at all, your phone is going to be struggling to keep up, which will also cause faster battery drain.

I hope you didn't pay much for this phone, because it's realistically not going to be usable much longer.

Also, stick with Rukbat's suggestion of not using Battery Doctor or similar apps. They run counter to how Android was designed, and fight the operating system. A lot of times they cause problems rather than fix them.

It's not supposed to be replaceable by the user...

I had to double check, because I thought all of the older G series phones were user replaceable (my G4 was). I learned something new today.

The more they can make the battery in odd shapes...

That's a common argument, but I think is a red herring. We've been told this ever since sealed batteries came out, but they have all still been a basic rectangular shape. I've yet to see a triangular battery, or L-shaped battery, or anything else odd and I doubt we will. It's just more economical to keep things a basic shape, and making them odd shapes would increase manufacturing costs. Personally I think they are the new normal because it's cheaper to produce a phone like that, and to push people towards a new $$$ phone rather than $10 on a new battery.