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11-11-2019

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Lenovo c940 - Charging via USB-C?

2019-11-11, 10:50 AM

Can the C940 be charged via USB-C?
What values does the charger need?

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14 Posts

11-11-2019

NL

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Re: Lenovo c940 - Charging via USB-C?

2019-11-11, 14:29 PM
Which model? 14" or 15"?

Still waiting for my 15" to arrive and i'm a bit concerned that charging using usb c wont work. I have a stardock usb c docking with a powerbrick that delivers 65W (and is compatible with Lenovo it says) so I hope it will charge (does'nt have to be quick but enough to keep it running).
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07-22-2010

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Re: Lenovo c940 - Charging via USB-C?

2019-11-11, 15:41 PM

Welcome to the forums.

 

Based on page 3 of manual I would say no if its the 15 inch.  If its the 14 inch then yes.

 

Per manual it supports the below.

 

Connect external display, storage, or data devices. Note: An appropriate adapter may be needed for connecting external devices. • Support data transfer rates up to 40 Gbps for Thunderbolt 3. • Support DisplayPort 1.4. • Provide up to 5 V, 3 A power output

 

https://download.lenovo.com/consumer/mobiles_pub/lenovo_yoga_c940_15irh_ug_en_201907.pdf

 


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22 Posts

11-06-2019

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Re: Lenovo c940 - Charging via USB-C?

2019-11-19, 23:54 PM

I've used two of the 14" versions Best Buy carries (swapped out one due to defective digitizer). Both did not take a charge from several different 60W chargers that provided max 3A output (20V-3A). I've monitored battery charge rates through HWInfo, and it was not slow charging either (dropping battery output when connected, but not showing charging). Turning the machines off and connecting them to 60W chargers also did not induce charging.

 

The only chargers I've gotten a charge result from are the included charger, and a few third party chargers offering 65W or higher. It seems the charging circuit will only recognize 3.25A or higher output, Voltage did not make a difference (the 65W chargers outputs 20V-3.25A, 60W chargers put out 20V-3A).

 

If you have docks offering 100W PD or at least 65W it's probably ok. Not sure if this is a firmware lock for some reason or Lenovo cheaping out on the circuitry required for converting between difference charging voltages/amps, but that's what I've encountered so far.

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8 Posts

11-21-2019

FI

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Re: Lenovo c940 - Charging via USB-C?

2019-11-21, 18:37 PM

Unfortunately, it seems that the 15" model doesn't charge via USB-C. I've tried it only with a "zendure supertank powerbank", which has a 100w USB-C PD output, and it does not charge. 

 

When I was looking for a new laptop USB-C charging was one of the main criteria on my list. When looking at the c940 15" it stated everywhere that the USB-C ports are Power delivery or PD compatible, which I understood that meant that they can give or take power according to the PD standard. Apparently I was wrong?

 

Any idea why Lenovo has opted to leave usb-c charging out?

 

It's pretty disappointing to find this out now and I'm considering returning the laptop.

 

Although the competition in the 15"/ dedicated GPU 2 in 1 segment isn't exactly spoiled with options right now. I guess the HP Spectre x360 is the only competition in town?

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11-11-2019

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  • Message 6 of 53

Re: Lenovo c940 - Charging via USB-C?

2019-11-21, 19:25 PM

I'm in the same boat as you, also bought this laptop so I could charge over usb c (although slow charge). Maybe it can be possible with a future update. 

 

Lenovo are you are reading this too?!

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8 Posts

11-21-2019

FI

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Re: Lenovo c940 - Charging via USB-C?

2019-11-21, 20:19 PM

This has really thrown a wrench in my plans, which is a shame, as I started to like the laptop.

 

I have until next week to decide whether to keep the laptop or not and would appreciate it if someone from Lenovo could confirm if the USB-C charging is not possible. 

 

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11-21-2019

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  • Message 8 of 53

Re: Lenovo c940 - Charging via USB-C?

2019-11-22, 20:58 PM

I contacted the local Lenovo support today about the USB-C charging and the claim they have on the spec sheet of the 15" model that it has 2x USB-C PD ports.

 

They just quoted the online manual of it having 5V, 3A output and that because it has 135W charger it doesn't support 100W charging, which to me seemed nonsense. After some conversation about the USB PD standard they promised to elevate the ticket to the next level and get back to me.

 

After some more looking into the USB PD specification, I'm even more confused as USB-IF states that:

 

USB Power Delivery offers the following features:

  • Increased power levels from existing USB standards up to 100W.
  • Power direction is no longer fixed. This enables the product with the power (Host or Peripheral) to provide the power.

 

https://www.usb.org/usb-charger-pd

 

But then again this TI training video states that:

 

"How do I know if I need a USB Power Delivery Controller? You only need power delivery if you require more than five volts, more than 

three amps, or more than just USB data, such as DisplayPort or Thunderbolt via an alternate mode."

 

https://training.ti.com/usb-type-c-vs-usb-power-delivery-whats-difference

 

So just having the Thunderbolt means that it's USB PD?

 

These different USB versions and standards are starting to get a bit confusing.

 

My conclusion to this is that because of the Thunderbolt Lenovo is stating them to be USB-C PD ports and that for some reason have decided to not include the two way (and higher than 5V 3A) charging. And that makes me sad :(

 

 

 

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32 Posts

08-30-2018

SG

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  • Message 9 of 53

Re: Lenovo c940 - Charging via USB-C?

2019-11-23, 15:36 PM

May I check if your 60W chargers are Power Delivery certified as well? I am planning to get the C940 but if PD is not supported it will be a deal breaker as I currently use a USB-PD power bank without issues on my IdeaPad 720s.

 

I understand QC 3.0 also uses 20V so maybe your charger is using that instead?

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22 Posts

11-06-2019

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Re: Lenovo c940 - Charging via USB-C?

2019-11-23, 16:35 PM

Both the 60W chargers I tried were PD certified. One was an Anker unit, the other was an Innergie. Both had worked on the HP Spectre x360 I tried before I switched to this C940.

It's dissapointing to hear the one poster's 100W pd dock didn't work. I was hoping that maybe it was due to the 3.25A delivery not being present on either of the 60W units. I assumed a 100W or 65W pd unit might have worked.

 

Sounds like it might be a firmware limit then, because the third party usb-c charger (similar to the original charger) does work. Perhaps someone more knowledgable at Lenovo would care to discuss the actual issue here?

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