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12-18-2019

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Re: Lenovo c940 - Charging via USB-C?

2019-12-24, 22:02 PM

 wrote:

All,

 

Just a drive-by observation:  you are talking about two different machines, the -14 and the -15.  The -14 is specified to charge via USB-C.  The -15 is not.

Yeah, it's confusing because of the lenovo numbering scheme... If they used something sane like c944 and c945 for 14" and 15" respectively, then we'd avoid all the confusion. As it is now there is a lot of cross-talk/confusion in these "charger and docking station" posts because some of us are talking c940 14" while others are c940 15"...
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Re: Lenovo c940 - Charging via USB-C?

2019-12-24, 22:05 PM

 wrote:

My laptop is C940 FHD 12G ram version.

I failed to charge it through USB C with a docking in a Benq monitor (pd2710qc).

The monitor docking outputs 61W only and this may be the reason that this laptop is not charged with it.

 


here again, we need to knwo are you talking c940 14" or 15" version?

 

But I think Lenovo is 'on the record' as stating we need 65W for charging the 14" c940.

 

 

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12-24-2019

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Re: Lenovo c940 - Charging via USB-C?

2019-12-24, 23:16 PM

 wrote:


 wrote:

My laptop is C940 FHD 12G ram version.

I failed to charge it through USB C with a docking in a Benq monitor (pd2710qc).

The monitor docking outputs 61W only and this may be the reason that this laptop is not charged with it.

 


here again, we need to knwo are you talking c940 14" or 15" version?

 

But I think Lenovo is 'on the record' as stating we need 65W for charging the 14" c940.

 

 


So sorry. Mine is 14" FHD 12G ram. I'm going to check with a different docking device and will update how it goes.

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Re: Lenovo c940 - Charging via USB-C?

2019-12-24, 23:25 PM

 


So sorry. Mine is 14" FHD 12G ram. I'm going to check with a different docking device and will update how it goes.


Ok, then you probably just need something that will do 65W.

 

Good luck with the search! Some have reported the Lenovo TB 2nd gen does charge the c940 14"

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01-13-2008

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Re: Lenovo c940 - Charging via USB-C?

2019-12-24, 23:28 PM

 wrote:

 wrote:

All,

 

Just a drive-by observation:  you are talking about two different machines, the -14 and the -15.  The -14 is specified to charge via USB-C.  The -15 is not.

Yeah, it's confusing because of the lenovo numbering scheme... If they used something sane like c944 and c945 for 14" and 15" respectively, then we'd avoid all the confusion. As it is now there is a lot of cross-talk/confusion in these "charger and docking station" posts because some of us are talking c940 14" while others are c940 15"...

You'll get no argument from me.  It's confusing for potential and current users... and for the mods...

 

Z.


The large print: please read the Community Participation Rules before posting. Include as much information as possible: model, machine type, operating system, and a descriptive subject line. Do not include personal information: serial number, telephone number, email address, etc.


The fine print: I do not work for, nor do I speak for Lenovo. Unsolicited private messages will be ignored - questions and answers belong in the forum so that others may contribute and benefit. ... GeezBlog

 

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5 Posts

11-26-2019

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  • Message 46 of 59

Re: Lenovo c940 - Charging via USB-C?

2019-12-24, 23:32 PM

Yep, seeNineForty, my Lenovo c940 14" provided power supply cord is stamped "Max 65W".

 

For others, just as a follow up to my Q&A posts 22, 25 and 27 with seeNineForty:


I am using a Dell Thunderbolt WD19TB dock - 190W source input, max 130W output to USB-C connector to laptop, 1 HDMI port, 2 or 3 USB ports, 1 Ethernet port, and 1 USB-C port.  My interpretation is the 60W delta (190 - 130) is meant to support any power needs of the ports.

 

My c940 handles everything I've connected (mouse, keyboard, CD read/write, monitor speaker, Ethernet) to the dock and also charges just fine.  I have the Lenovo Vantage app managing/controlling my laptop battery charging.

 

I also have my dock and monitor plugged into a dedicated surge protector power strip.  I turn off the power strip after I shutdown my c940 - to save on my electric bill.


It's sort of cool - I turn on my power strip, then turn on my laptop, and everything comes to life without any other clicks, logins, buttons to push, etc.  I thought I'd have to dive into c940 settings to get my setup to work that way I wanted, but I did not have to do anything.  It's been a plug and play experience as far as I am concerned.

 

seeNineForty understood my comments as mine and not as a Lenovo expert.  For everyone on this thread, to the moderator's point, here's the disclaimer - I am not an expert on the c940.  my test shouldn't be construed as a Lenovo certified answer.  I was willing to try this Dell dock on my own and at my own risk.  I just had faith Lenovo would adhere to most common standards.  What worked for me may or may not work for you.

 

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01-07-2020

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  • Message 47 of 59

Re: Lenovo c940 - Charging via USB-C?

2020-01-07, 2:08 AM

I just received My C940 and have some more data points to share.  It's a 14" with 4k screen.  It's running firmware AUCN45WW.  The bottom has some specs written on it: Lenovo Yoga C940-14IL; Model Name 81Q9; Input 3.25A@20V.  It shipped with the battery at about 50%.  Before turning it on I plugged it in to 3 different AC adapters:

 

The included AC adapter is model # ADLX65YLC3D.  It advertises 3.25A@20V, 3A@15V, 2A@9V, and 2A@5V.  I had no way of testing the current, but with a PD tester it does output 5V, 9V, 15V, and 20V, and not 12V.  Before turning the laptop on and setting eco mode, it charged the laptop at 15W, oddly slow all things considered.  Now, whetherpowered on or in standby, it charges at 63W.

 

The next 2 AC adapters I tried are Anker PowerPort Speed PD 30, and Anker PowerPort II PD.  Among other things, both output 1.5A@20V.  The cable I'm using is an Amazon Basics brand, 5Gbps data and 3A power capable.  Before turning on the laptop both would charge it at 28W.  With it turned on I get a slow charge warning on the screen, but it draws 29W and the battery indicator does increase.

I don't know if I just got lucky with a working setup.  The first thing that usually goes wrong when I'm troubleshooting someone's cellphone charging is the cable.  If the AC adapter tells the laptop it's capable of 5A@20V (through PD communications) then this laptop will probably try to draw a full 3.25A.  If the cable is only capable of 2A then the laptop might start seeing undervoltages and shut down charging.  It won't know to limit to 2A, it will only know that 3.25A fails.  With a 1.5A charger it will only try to draw 1.5A.  Of course, if the cable is built in to the AC adapter then chances are it can handle the current the AC adapter advertises.

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137 Posts

12-08-2019

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Re: Lenovo c940 - Charging via USB-C?

2020-01-16, 21:08 PM
@madcow3417 Your c940 is charging at 63 watts while on? Can you provide a screenshot of either BatteryBar or HWInfo showing it's charge rate? Very interested in seeing this if yours charges more than 15,000 mW while on.
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01-07-2020

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  • Message 49 of 59

Re: Lenovo c940 - Charging via USB-C?

2020-01-18, 1:07 AM

I did all these tests with a 60W Aukey PA-D3 power supply.  I installed the portableapps version of HWiNFO and it reads a charge rate of 13874mW.  it doesn't change, I think it only takes one reading when opening the program.
At the same time I checked 3 other power monitors, both before and after the AC adapter.  Power goes way up when I turn up my brightness and set best performance, but right now they're minimized.  All these readings are bouncing around, so I'm doing my best to average.  My clamp on multimeter reads about .4A @ 120V before the AC adapter, or about 48W.  Another power monitor reads 40W before the AC adapter.  My USB power monitor after the AC adapter reads about 1.5A @ 19.9V (30W), occasionally jumping up to about 2.5A.  I assume it's lower because it doesn't take into account power loss in the AC adapter, and the other ones average in the 2.5A jumps.
I have a theory about the discrepancy between HWiNFO and the power monitors.  It may be that the charge rate is based on the power going into charging the battery, but what I'm measuring is the total for running the system + battery charging.  Alternatively, the charge rate could be a totally wrong value reported by the system, which happend to some peope in the HWiNFO forums.

https://www.hwinfo.com/forum/threads/charge-rate-different-to-measured-value.3203/#post-14787

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01-29-2020

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  • Message 50 of 59

Re: Lenovo c940 - Charging via USB-C?

2020-01-29, 10:48 AM

I as well have a Yoga C940 14IIL (Model 81Q9) and I want  to use it with a Thinkpad Thunderbolt 3 Dock Gen 2.

This is my experience:

- Clean install of Windows with Media Creation Tool

- Only Windows Home installed (checked Bios for License and chose automatically Windows 10 home edition

- Upgraded to Windows 10 Pro with License Key

- Added to Domain

 

  • Thunderbolt Dock comes with 2 power supplies (230W and 65W)
  • Thunderbolt Dock charging cable only works with ThinkPads, not Yoga - originally no charging through USB-C
  • Tried 135W charger rom a colleague, then the Yoga was charging
  • Connected 230W power supply to 65/135W input, laptop was charging

 

When not connected to dock, all fine, but whenever connected to dock:

  • Keyboard was missing tiped keys, reacted very slow.... must press hard.... unable to work like this
  • Firmware update of Dock
  • Keyboard is now fine
  • no charging through USB-C via Dock possible

 

These are my findings. Doesn't do what it's supposed to do!

Best regards,
Philipp

 

 

 

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