Why does my battery drop from 100 to 98 immediately?

[AC Question]

Battery drops from 100% to 98% immediately.

Initially when i got my s6 and it charged to a 100%, it would stay at a 100% for a little while regardless of heavy use or not before it started declining. However, during the last two charge cycles, it charges to a 100%, I turn it on and it immediately drops to 98%. Ive had it for about 2 weeks now. Any of you guys having this problem? Im thinking of bringing it back in because i am in fear this is a warning sign of problems to come.

 

[Dajun Chou]

Re: Battery drops from 100% to 98% immediately.

Drop 2% is normal, man. Do not unplug your phone as soon as it reaches 100%, charge it for 10 minutes more instead. Your phone indicates 100% but it is not fully charged actualy.

 

[Rukbat]

Re: Battery drops from 100% to 98% immediately.

We measure State of Charge by measuring the voltage at the battery terminals. (Making batteries that can have actual chemical SoC would mean batteries that cost more than flagship phones.) When the charger is charging the battery it has to present a higher voltage to the battery than the battery voltage. (Current flows from the higher voltage source to the lower voltage load - like water flowing downhill.) So when the phone just reaches the 100% SoC mark, we're measuring the charging voltage, not the battery voltage - and on the curve used to translate voltage to SoC, that's 100% even though the battery voltage is at the 98% point on the curve. The battery isn't fully charged yet. Give it another 30 minutes, and when you disconnect the charger, you should stay at 100% for at least a few minutes. (The screen draws a lot of current.)

Given the state of the are, and economics, it's the best we can do at the moment.

 

[Dominic Gayle]

Thanks guys. I did what both of you said and sure enough, the batt. percentage stayed at 100% for like 10 minutes.