Samsung Super Fast Car Charger dual 45W and 15W

[nocturnal009]

I have the S20 Ultra 5G and just bought the Samsung Super Fast Car Charger dual charger connected to the USB c 45w port sometimes it charges super fast and sometimes it doesn't charge at all and there are times it will charge very slowly.

I restarted the phone same result

Fastory reset same result. 

Tested the car cigarette lighter port with multimeter and the voltage is above 12 volts DC. 

Enabled all battery fast charging toggles to on and same result.

Using original USB c cable that came with the car charger.

Tried different USB c cable on the 45w port same result. 

All of the above trials showed that I was connected to super fast charging 2.0 but it would not charge. 

Also tried the 15w port same result. 

Phone charges very fast only using the super fast AC charger. 

What is the problem here??? 

[BasselK]

Please keep in mind to keep your phone away from direct sun light exposure during charging, as it can increase your phone temperature and can affect your phone battery lifetime and charging speed.

[nocturnal009]

Hi Basselk I took the car charger out of the car and kept with me in an air conditioned office and when I returned to the car it would charge very slowly it didn't make any difference whether the car charger is cold or hot it was still charging extremely slow

[nocturnal009]

I tried the ac charger USB c cable that came inside the box of the phone same result then I bought an ANKER USB c expensive cable same result

[nocturnal009]

The port that the charger is connected has a label that shows 12 v max 180 watts

[nocturnal009]

That's not the cigarette lighter port which is the other one but even that I tried same result

[nocturnal009]

It's super slow charging even if I don't put the phone under the sun I'm really not sure why this is happening because if it was the phone and it's battery then at home it would charge slowly using the ac charger but at home it charges super fast so what is the issue here? It's been like that ever since I bought it and I think I read somewhere in the manual that fast charging will sometimes not work depending on certain conditions what these conditions are remains a mystery

[nocturnal009]

I tired the above tests using 120hz mode and 60 hz display mode with 5 g and 4g only and power saving mode enabled se result so should return this charger and get a replacement???