When your Samsung phone slows down, drains fast, or randomly switches off, it’s time to get a replacement battery. Usually, a phone battery lasts 2-3 years at 400-500 complete charge cycles before the amount of charge your battery can hold starts to decline.
You can also check your battery health and your current running capacity by going to the Play store and downloading a battery health app. If your battery health is below 80%, it means that you may need a replacement battery for your Samsung phone.