I have a wireless disc charger for my Galaxy S8. For some reason when I connect it to the factory wired charger it most often gives me a slow-charging warning, though not always. No idea why. Anyway, it led me to wonder, if I charge it with the cable, and also set it on it on the disc, will it cause damage? Will it charge faster? No difference?
As always, thanks in advance.
In most if not all cases, inductive charging is shut down when it’s plugged in. Samsung may have had faulty batteries in the past, but they can anticipate people doing things like this.
Oh, and about the slow-charging warning: USB is always 5 volts, but it’s the voltage times the current that gives you the power, so the more current you can get through, the faster you can charge. The original USB standard was capped at one amp (or maybe half an amp; I might be misremembering), but modern versions can allow higher currents, if the device and the charger negotiate for it. So if you take a device that expects a high current, and plug it into either a low-current source, or a modern source but the negotiation doesn’t work right for some reason, it’ll charge more slowly than it expects.
The OP mentions using the “factory wired charger” which I had interpreted to be the OEM charger that ships with the phone.
Yes, it’s the AC adapter that came with the phone. Says “Adaptive Fast Charging” right on it. It’s worked since I got it in December, only been an issue for the last few weeks. Tried different outlets, tried flipping the phone connection (which shouldn’t matter since it’s USB-C). I’m thinking it’s the adapter, which I assume is covered under warranty. I suppose I can just take it to the T-Mobile store but wanted to see if anyone had an idea or experience with this and save a trip.
I’m guessing the cord is dying or possibly dirty. And it might yell at you if you use another brand but you can’t hurt anything. As Chronos points out, it will draw as many amps as it needs.
0.5 A was the original standard, so 0.5 x 5 = nominal 2.5 watt
There might be a phone setting to allow fast charging.
My galaxy S8 has also started having issues with slow charging instead of fast charging, even with the original charger and various cables, for the past month or so. I cleaned out the usb port on the phone with a can of air, and it’s been mostly better, but I did have a charging failure again the other night.
Same here with my Note 8, it sometimes tells me I’m slow charging when I’m using the original cord and charger. I can flip the usb c connection and it charges at the fast rate. I’ll try the air can and see if it helps. Any other suggestions, I never had this problem with my micro usb chargers.
Yeah, like I said if I flip the USB-C connection it sometimes helped. Which shouldn’t make sense because it’s supposed to work either way. Funny about the canned air. I blew into the port and the connector and had a Nintendo flashback. 
I’ll give it a try.