Battery issue with second hand phone - can someone decode diagnostics?

I bought a second hand iphone 5 the other day, I checked it out throughly but now I'm getting this issue:

Once the battery hits 26% it crashes, black screen with circle and displays "charge battery" symbol.

When you plug it into charge it doesn't take time to start back up like normal it starts up immediately and always shows a charge of 32%.

I have 3 sets of diagnostics from it as screenshots, can someone who can decipher it take a look and let me know what could be the issue?

Appreciated in advance.

Dropbox link for screenshots: https://www.dropbox.com/sh/d0ohaef38we1cmw/kX0ETfWcD-