Realistic fast wireless charging speed

[YuanhaoYoung]

I recently bought a fast charger for my car (Rocoren 4-port PD, which supports up to 30W) and a wireless charging phone holder. When I put my phone in the holder, it says Fast Wireless Charging, so the phone can detect the charger supports fast charging. But eventually this changes to Wireless Charging. Using AccuBattery, I can see the wattage varies between 2w and 3w, which seems low. But if I go into settings and turn off Fast Wireless Charging, then the phone takes even longer to charge.

I also tried this with an Anker fast wireless charging stand and got pretty much the same result.

Realistically, should I get closer to 10w or 15w? If not, what should I be getting?

 

[B. Diddy]

At what battery level does the charging rate drop down? Keep in mind that as the battery approaches 100%, charging rates always slow down -- it's the nature of how a battery is charged.

 

[YuanhaoYoung]

It doesn't seem to matter. I've seen this when the level is around 50%. I do have the protect battery setting on, to limit max to 85%.

I forgot to mention that if I connect directly to a fast wired charger, it works great. Very fast at the same battery levels.

 

[B. Diddy]

Does the phone get pretty warm while charging wirelessly? That might also affect charging speeds -- it might automatically drop down to slow charging as a safety measure.

 

[YuanhaoYoung]

I'm not sure. I'll have to check that, although I think it starts off slow even before it's had a chance to warm up. Thanks for the suggestion!

 

[Laura Knotek]

Are you charging more than one device at a time? Which USB port are you using?

Which wireless charger are you using with that USB car charger?

 

[gomezz]

I recently bought a new Anker wireless stand which supports fast charging. But when I tried it with any of my existing USB charger plugs it would not go fast. I then realised I also needed an new USB charger plug to use with it that could deliver the extra power it could accept. From what I could see an S20 only accepts up to 19W anyway and in practise that seems to take about 50% longer to charge than a direct cable.

(I have an older wireless charging stand in the bedroom that does not do fast charging but as that is for overnight charging then not an issue)