Solved: S21 Ultra charging slowly with 25W charger

SgtRepeat · ‎24-04-2021

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?

SgtRepeat · ‎03-05-2021

So I've had a weird resolution to the issue.

I stay in India where it's summer now & the temperatures are really hot (around 32-34°C inside the house) . So, I switched on the air conditioning, set it to 24°C, and started charging my phone. To my surprise, the phone charged from 5-100% in 1 hour 5 minutes!

I tried it a few other times & the results were the same. The moment I tried charging the phone in a room without air conditioning, it took 1 hour 30 minutes.

It's really strange that a room temperature difference of a few degrees results in an added 25 minutes of charging time!

I wonder if this is normal for all Samsung phones as I didn't face this issue with any other phone.

View solution in context

tinglish · ‎24-04-2021

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

antikythera · ‎24-04-2021

That makes perfect sense.

tinglish · ‎24-04-2021

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

KIUSHA · ‎25-04-2021

It is adaptive,to safe battery life

SgtRepeat · ‎25-04-2021

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

SgtRepeat · ‎25-04-2021

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 · ‎25-04-2021

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 · ‎25-04-2021

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 · ‎25-04-2021

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.

Original topic:

S21 Ultra charging slowly with 25W charger

1 Solution