You are using your phone as you usually do. But you realise the battery is empty again and again and usually within the shortest time. You end up charging and recharging the battery performance just becomes worse and worse. Then you end up not even getting 15 minutes after a full charge. Then the battery completely dies. If your phone has a replaceable battery it is quite simple, you buy a new battery yourself and place it in the phone and da-da.
Unfortunately, most modern phones do not have an easily replaceable battery. To do this, the phone must be opened. Then you can take out the faulty battery and replace it with a new one. The new battery life is just as good as when you had just bought your phone!
Basically, all batteries used in smartphones can be affected by degrading performance over time. With a brand new phone you would enjoy the maximum capacity, but as years go by, that capacity will slowly deteriorate until the battery dies completely.
Whenever you feel that you aren’t getting enough of the battery then its best to replace it. If you only have 40% of your battery left in your tablet or laptop, but it still lasts long enough for you to check your emails each morning, then that’s fine. If however you’re on your phone all day and it’s running low by lunchtime, then a replacement could be in order. Most smartphone batteries will last for at least one or two years, but this can vary based on your usage.