Battery life - total screen on time? how much would an extended battery improve?

[unvaluablespace]

I have an old s4 mini lying around that I am planning to use as a baby monitor for a wyze cam. the battery is probably old and on my testing only showed a total screen time of just barely 3 hours. I was wondering if a new battery would give me better battery life and, if so, how much longer would an extended battery give me? keep in mind this is for total screen on time streaming video/audio feed from a camera, as it more than likely wont be used for much else.

Thank you

 

[MrGoodtunes]

Is there some reason why you can not just hook up a USB charger to it, and leave it on while in use? (Maybe it gets too hot?)

 

[Nex]

I have an old s4 mini lying around that I am planning to use as a baby monitor for a wyze cam. the battery is probably old and on my testing only showed a total screen time of just barely 3 hours. I was wondering if a new battery would give me better battery life and, if so, how much longer would an extended battery give me? keep in mind this is for total screen on time streaming video/audio feed from a camera, as it more than likely wont be used for much else.

Thank you

I have a "new" s4 mini battery, it is "new" because it was bought a long time ago, but it was not used much.
It is the original, and it gives me between 3 and 4 hours of screen, in very extreme cases 5.