When I put my S21 on charge it powers off.

[Equivz]

When I put my S21 on my 45w fast charger it just powers off. Could someone please explain as to why.

Many thanks.

[Egg1]

It's probably turning itself off as a fire precaution.
Some might have expected the Galaxy S21 and Galaxy S21+ to get 45W fast charging. Their predecessors maxed out at 25W. If Samsung were to ensure continuous improvement of their features, perhaps it would offer higher charging speeds. It doesn’t. Both of the new flagships can charge your phone at a maximum of 25W.

[GoanGeek]

Fast charging seems to heat up the phones.

I recently noticed that my phone heats up if I use my 25 Watts charger.
So maybe as mentioned its shutting off as a precautionary measure to protect itself.
Try a 25 Watts or 15 Watts charger.

Ideally s21 ultra supports upto 25 Watts charging and mine is an official charger.
It doesn't shut down but gets pretty hot.

[Equivz]

@GoanGeek
I just plugged my phone into my 15w charger and it just shut down.

[TessM]

Hi @Equivz ,

are you using Samsung genuine chargers? Is the phone turning off without any warning after plugging this in? 

I would also recommend running a Diagnostics to see if there is anything wrong with the battery or the port from the Samsung Members app> Support> Phone diagnostics> Battery status first and then Cable charging.