Note 9 Charges Faster When Fast Charging Is Disabled?ive been

[Android Central Question]

I've been having a repeatable problem. I have a Note 9 that will charge faster when I disable fast charging under battery settings. I tested the load being drawn with a USB Power meter, and these are the results I got.

When QC is enabled:
Phone draws 0.5amp charge, 10ohms resistance at 5.02V.

When QC is disabled:
Phone draws 1.2 amps, 3.9 ohms resistance, at 5.02V

I am using the same cable, same power bank. The power bank is able to draw 1.9amps at 5V, tested using a USB Meter and Load Tester that will put the USB under 1 amp and 2 amp loads.

When I immediately switch between QC and non-QC, the results above are repeatable.

Things I Have Done So Far:
Reboot Phone
Clear Phone Cache
Reboot Into Safe Mode
Try Different Charging Cables, Blocks, including OEM parts.

Every once in a while, it will switch back to QC fast charging but it is random.

My phone's wireless charging has no problem operating at it's max capacity

Any one else have this problem? Anything else I could do before I factory reset my phone?

 

[mustang7757]

Hi, welcome to Android Forums

I'd like to recommend creating a account so me or other members can assist you, as guest have limitations in replying here and if we need further Information to communicate with you.

I'll provide a link to register, please come back to your post so we can further assist

https://forums.androidcentral.com/showthread.php?t=409154

 

[mustang7757]

Only thing if it happens in safe mode ,try factory reset

 

[Rukbat]

According to Ohm's Law, your numbers work, so the question is why the phone presents a higher resistance with QC enabled than with it disabled. Rough guess - the switch is mislabeled - Enabled means Disabled. (I've seen this kind of things many times when someone writes a UI for a language not his first one - the UI designer misunderstands how the term is used in that language.) Just keep it disabled when you want it on. 1.2 Amps still isn't much of a charge for a 4 Amp-hour battery (.3C - when the battery could safely be charged at 0.999C), but that's Samsung's fast charging for the Note 9.

 

[TheWounded]

You actually saying his Note 9 has a mislabelled Fast charge setting.
That's just a **** comment.

 

[Mooncatt]

Have you removed the USB meter and ran any tests? It could be that the meter isn't compatible with that fast charging protocol, thus defaulting to the standard USB protocol (.5A@5V is the USB 2.0 standard, if I'm not mistaken).

The meter is the one variable you haven't checked. So remove that and connect the phone direct to the charging block. Then either use an app (I prefer this one for its recording ability while the screen is off https://play.google.com/store/apps/details?id=ccc71.bmw ), or simply use a stopwatch to compare charging rates.