How will I know if the battery is time to replace?

Hi!

First off, use a better diagnostics app to see if there are any obvious problems (like a depleted battery). You can also try to do the following to (re) calibarte your battery:

1. Charge your phone till 100%.

2. Use it until it shuts down. (When it shuts down, try to power it on a few times over the course of an hour just to make sure it doesn't start)

3. Connect it to the charger, shut it down the moment it powers on and leave it there for about 4-6 hours.

4. Power it on and use it normally,

5. Drain your phone, use it until it turns off then repeat steps 3 and 4.

6. Return to your regular charge cycle.