Why Doesn't My USB Charging on Computer Work When The Computer is Off/Sleeping?

[ptonantryloc]

USB Charging on Computer Doesn't Work When Computer Off/Sleeping

EDIT: This is not just a Daydream issue. It's a USB charging issue.

Original Post: Normally, I keep my phone plugged into my computer in charging mode via USB. That way I keep the battery charged and can use the phone as a clock via Daydream (Daydream set to go on when phone is either charging or docked). With my Nexus 5, this worked fine. With the Nexus 6P, it works while the computer is on. But, when the computer goes to sleep or I turn it off (or even if I merely reboot the computer), Daydream goes off. Both phones are running Android 6.0, are configured the same, and have the same fully-updated software/apps. I'm (obviously) using a USB-A/C cable with the 6P, so the cable is different. But, those cables were plugged into the same USB port on the same computer with the same operating systems. Is anyone else having the same problem? Does anyone know of some other setting somewhere on the phone that I might have missed?

 

[ryleyinstl]

Re: Daydream Doesn't Work When Computer Off/Sleeping

What kind of output are you getting with the USB port/cable combo on your computer? If less than 500mA, perhaps that isn't enough to register as charging on the 6p?

 

[ptonantryloc]

Re: Daydream Doesn't Work When Computer Off/Sleeping

I have no idea what the output is through the USB port/cable from the computer. But, I just plugged both the Nexus 5 and 6P into the computer via USB ports at the same time. When the computer is running, both phones show as charging. As soon as I put the computer in sleep mode, the Nexes 6P stops charging, yet the 5 continues charging away.

This is really weird behavior. After thinking about it some more, it looks like with the Nexus 5, the charging status is determined at the physical layer (or some other low layer where the phone knows that it's physically plugged in an sees the electrons whizzing through the port). With the Nexus 6P, it looks like the phone wants the OS or driver to tell it that it's plugged into the USB port and is being charged. As soon as the OS goes away, the phone thinks it's not being charged any more.

If anyone else is reading this, I'd really appreciate it if you plugged your 6P into a USB port and see what happens with your computer on, asleep, and off. It would be really nice if you could do the same with any other phone you might have lying around.

EDIT: I stuck a Nexus 9 tablet onto a USB cord into the computer and it behaved exactly like the Nexus 5.

 

[ptonantryloc]

Re: Daydream Doesn't Work When Computer Off/Sleeping

I waded through a bit of the power stuff for USB at:

https://en.wikipedia.org/wiki/USB#Power

It looks like the standards for USB power are:

USB 1.x and 2.0: 500mA / 5V / 2.5W
USB 3.x: 900mA / 5V / 4.5W
USB-C: (500/900mA / 5V / 2.5/4.5W) & (1.5A / 5V / 7.5W) & (3A / 5V / 15W)

So, the USB-C port on the Nexus 6P should charge just fine at those legacy amperage/voltage/wattage that work with older phones.

I'm using a USB-A/C charging cable:

http://www.amazon.com/gp/product/B010VFFRCE?psc=1&redirect=true&ref_=oh_aui_detailpage_o01_s00

which Benson Leung (an engineer at Google on the Chromebook Pixel and Pixel C teams)

http://www.amazon.com/gp/pdp/profile/A25GROL6KJV3QG/ref=cm_cr_dp_pdp

has tested as being properly designed. So, the cable shouldn't be the issue, either.

 

[dty06]

Re: Daydream Doesn't Work When Computer Off/Sleeping

Some computers will cut power to their USB ports when sleeping to save energy. This could be a setting in Windows/Linux/OS X (whichever you're using) or it could be a setting in the computer's BIOS. Not sure why the difference between the Nexus 5 and the 6P, though. If it's not a power setting in the OS or BIOS, it could be that the OS treats the USB-C differently than other USB devices. Maybe the 5 was installed as a certain kind of device (i.e. Google Nexus 5 Phone), but the 6P is installed as a different kind (i.e. "Generic USB Media Device" or something). Check what the 6P is recognized as from the Device Manager (assuming you're using Windows).

 

[ryleyinstl]

I'd say you're getting some voltage drop when the computer is in sleep mode. There is enough for the 5x to charge but not enough for the 6p.

Check the motherboard manual, some newer computers have dedicated USB ports which will supply full (or even 2A) power for charging devices even when in sleep mode.

Posted via the Android Central App

 

[N4Newbie]

Re: USB Charging on Computer Doesn't Work When Computer Off/Sleeping

I'd say you're getting some voltage drop when the computer is in sleep mode. There is enough for the 5x to charge but not enough for the 6p.

Check the motherboard manual, some newer computers have dedicated USB ports which will supply full (or even 2A) power for charging devices even when in sleep mode.

Posted via the Android Central App

Correct. Yellow ports are "always on".

 

[ptonantryloc]

Re: USB Charging on Computer Doesn't Work When Computer Off/Sleeping

A bit more information:

- First, I double-checked the lack of charging with the stubby little USB-C/A Google provided. Even with that, the phone insisted it wasn't charging. So, it's not the cable.
- Second, I installed the Ampere app from the Google Play Store on both the Nexus 5 and the 6P. While the computer was awake, they both pulled currents of anywhere from 20 to 220 mA at around 4.3 volts. When the computer was asleep, they both did the same (and the 6P battery icon showed charging, to boot).
- When I installed that app, it said these phones running Android 6.0 would always show 0 amps unless I "used the old method" to measure. I had it do so in both cases. I don't know if that's what changed the phone's behavior or just the fact that the app was installed.
- I uninstalled the app from both phones and the 6P continues to charge correctly while the computer is asleep. Maybe the app's "old" measuring method is now part of the phone. Maybe something changed on the phone. I don't know.

So:
1) It looks like when my computer is asleep, the USB ports remain fully functional. I don't know how much I trust that app, though. So, I've ordered a little USB multimeter type of thing which should be here in a couple of days. I'll measure the voltage and current with that when I get it.
2) I would REALLY appreciate it if someone would plug their Nexus 6 into their computer's USB port, put their computer to sleep, and see what the battery charging icon at the top of the phone's screen looks like.