Phone battery charge level. Remaining 20% fast drop to 1% or 0%

Hi,
Is something wrong with phone battery when there are 20% remaining, but after I start to use my phone, the battery drops fast to 1% or 0% ?

Fast drop of battery charge level should not happen in case of new battery.

But if your phone is intensively used and you charge the battery often, then it could happen that battery level drop faster from 20% or 10%.

Fast drop of battery charge level from 20% to 1% can also happen:

• If you often give short charges to your battery (short charge cycles)
• If you don't use the phone for a longer time
• If there is a cold weather (battery drains faster when it is freezing)
• If charge indicator is not working correctly

I have a cheaper tablet and battery charge drops from 20% to 1% quite fast.

Faster battery discharge started after a couple of months since the tablet was bought.

In general, the overall battery run time is good, but it starts drain faster from approximately 20%.