S21 Ultra charging slowly with 25W charger

[SgtRepeat]

My S21 Ultra is taking 1.5 hours to charge from 5-100% with the Samsung 25W super fast charger and the cable supplied with the S21 Ultra.

And I have fast charging and super fast charging enabled on my device.

All the user reviews & battery charging tests online show that the S21 Ultra takes roughly between 1 hour 9 minutes to 1 hour 15 minutes to do a full charge from 0-100% with the Samsung 25W Super fast charger. 

Any idea what is going wrong here? Is it an issue with the phone, cable, or charger? 

[tinglish]

Just have super fast charging on,turn fast charging off.
This is what I had to do,hope this helps 👍

[antikythera]

That makes perfect sense.

[tinglish]

Yeah for some reason mine wouldn't fast charge with them both switched on 🤷

[KIUSHA]

It is adaptive,to safe battery life

[SgtRepeat]

Does it matter if the always on display (AOD) is on while charging? Will the AOD affect the charging speed? 

[SgtRepeat]

I disabled the Fast charging option & only turned on Super fast charging.

It took 1 hour & 37 minutes to charge the phone fully from 5-100%. This is 10 minutes more than what it took with both fast & super fast charging options turned on.

I'm at my wits end now. 

[Joeeye]

This would indicate that either AoD is draining significantly more than normal or you have other processes in the background consuming power while it's still charging. 20m more isn't much longer but it's significant enough to tell that your phone is burning more power than usual when idle.

You are correct in charging times for the S21 Ultra using 25W super fast charging (mine from 0-100% is 1h 15m~).

[SgtRepeat]

The screen (including AOD) is completely off while charging. Also, I've ensured that I don't use the phone at all while it's charging.

I'm starting to wonder if the 1 hour 10 minutes charging time is only when the phone is in flight mode or switched off completely. 

[Joeeye]

My times were measured while off. Never done a full charge time whilst on, but I'll make a note to on next cycle. I typically try to charge around 30% to 100% while on, this usually takes just under an hour.