have you adjust anything in Bios settings to Charge laptop via USB-C? I have P52 and a adapter 65W PD, and I can not charge my laptop via USB-C. Have you got ideas for my problem? thanks!

No, I couldn't. Actually I bought the charger I linked here earlier for my P50. 

It was able to run on it, but did not charge until powered off. 

Recently I changed the P50 for a P52 and guess what... 

It does not charge on the 89w PD and it does not run on the adaptor I used before (the 4x USB plus USB C with Lenovo tip).

I certainly disappointed and **bleep**ed up by Lenovo. 

What moron designed the charging circuits? 

The device can basically only be used with an original charger with equal or greater than 135W.

Can somebody from Lenovo please check and revert back to this issue? 

I remember that others before mentioned that they are able to charge via USB C on the same device... 

You can probably use a different tip, w/o the resitor, and trick your P52 to believe it's seeing 135W adapter. http://www.thinkwiki.org/wiki/Power_Connector 

Hi!

No, as written on the ThinkPad_P52_Spec.PDF, the PD on USB-C it OUT only. As many already mentioned, USB-C PD is max 100W while the computer can require 170W+.

If Lenovo allowed PD IN on USB-C, I'm sure they would get all sorts of support calls from people who just assume that because the plug fits and they can charge some other devices that it should work and complain that the battery discharges while the machine is "plugged-in" (but under-powered). So, instead of losing time to troubleshoot users who had not RTFM (as the machine is not at fault), they likely just turned the possibility "off". Why build in a function that works only part of the time in some edge cases and causes support calls as a result?

So, short answer: No, because it cannot work 100% of the time.

Martin

@p600 good idea! I've just ordered an female(square)-->barrel and one barrel-->male(suare) adapter.
I'll just cut them and change the total resistance incl. the charging cable from the other supply.

The good thing is, most of the time, the device uses WAY less than 90W. And if the charger has too much demand for power, it will just switch off. So nothing that will be a problem.

@ve2mrx : I fully disagree. Not sure if you got a P5X - but it is perfectly fine for travel. (at least for me). Since I travel a lot - I really carry enough cable n stuff. So it is a hassle to carry the 135W brick with me.
Therefore I could perfectly live with a sometimes underpowered device.
And beside: We are in 2019, not in 1985 - so what is the point in using the battery as a buffer for the higher loads and even charge the same during times of lower loads? If Lenovo is not bright enough to design such a system, how can we expect any kind of a "smart grid" for HV, MV & LV power-lines?

Regards...

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 wrote:

@ve2mrx : I fully disagree. Not sure if you got a P5X - but it is perfectly fine for travel. (at least for me). Since I travel a lot - I really carry enough cable n stuff. So it is a hassle to carry the 135W brick with me.

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Hi!
I do own a P52. I took a slim carry case for it and I enjoy using it on the road. I always carry the 170W power adapter in the case too, along with a cable to charge my phone through the laptop!

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 wrote:

Therefore I could perfectly live with a sometimes underpowered device.
And beside: We are in 2019, not in 1985 - so what is the point in using the battery as a buffer for the higher loads and even charge the same during times of lower loads? If Lenovo is not bright enough to design such a system, how can we expect any kind of a "smart grid" for HV, MV & LV power-lines?

---

I do understand you would accept a machine that's limited, but consumers hate limitations, and it adds complexity to an already complex system. Besides, don't forget a P52 is a Workstation-class machine, usually sold in a tower format.

In a laptop, there are thermal limitations as well as power limitations that just don't exist in a tower workstation. And yet, those who buy such workstation laptops dislike those limitations. I guess Lenovo preferred to require more power not to limit the machine, at the expense of needing a bigger power adapter.

I studied in electronics and I know the limits of flexibility. What you are asking for is nowhere close to simple. You are asking the computer to figure out how much power is available, tell the power regulators to limit themselves to this new limit, tell the CPU to use less than its designed 45W TDP, tell the dGPU to limit itself too, as well as tell the battery charger how much is left. All while using a range of possible input powers and sources. Oh, and it all must be perfectly stable, as users hate crashes. Yes, it can be done. It will add cost (another thing users hate!) and complexity (more software too, which means more bugs!).

Now, that will be useful for what percentage of users? How many would buy this mobile machine and purposely use it under-powered while being mobile? Let's say 15%. So, then, let's charge 85% of our users for a useless feature (to them)? That's what is called feature bloat. And it pushes potential customers to the competition as the machines are more expensive. Keep this in mind, Lenovo has to make it work on a scale. 

Now, I'm not too sure what is your point about 1985, but I can say it makes perfect sense to use the battery to stabilize the power supply. That's exactly what your car does. And it is a very efficient way to do it as the battery is already there (so no added weight), and no added parts (lower cost, less chances of defect). I have to side with Lenovo on this, sorry.

I'm sorry, but although it looks simple to "do", having USB-C charging on the P52 and higher is not as simple as letting the computer "take" the power. And USB-C PD is not a good idea at those power levels anyway. Sorry!

If you have specific questions, please ask. In the meantime, I suggest you power your accessories from your laptop instead of your laptop from your accessories. The power quality of the laptop power adapter is certainly better than the USB-C power adapter quality (in general). 

I know, it's a long reply,

Martin

Alright, this is your opinion...
But in general I really wonder - you refer quite often to "us" but in yyour signature you state that you are an individual instead of an Lenovo official...

And still I agree to disagree.
I'm an industrial engineer, which also involves about 1/3 of my academic studies to be electronics. So you are not talking to an barber... ;-)

In my opinion, someone that buys a mobile workstation does it because of mobillity. And it does not add any convenience in mobility to carry a power-birck at the size of a van.
You also completely missed my point, I had been not talking about any reduced power / speed. I think that it should be possible to run the workstation in an adaptive mode, which can buffer energy-consumption-spikes from the battery. Unless you encode 60 minutes of 4K video or render a animation from Autodesk-Inventor for 1h, the machine is mostly in idle or medium power-state.
During that time any <90W power-supply is fine. And during the peak-time the battery can kick-in and together with the PSU it will be enough to run on full speed. It only needs to reduce the speed when using high-power for a longer time and the battery is drained.
But how often does that occur? In my opinion almost never.
If you are someone that utilizes the CPU & GPU almost to the fullest all the time you might have a very special job.

For the complexity: I think this is rather cry-wolf style! If you see what could be done and is done actually technical-wise, these little tasks you mentioned should be no problem at all. This can be done with a IC worth some pennies. But there needs to be a will to do so.
In some other way there are already these function implemented, but the only thing which need to be done addtionally is to query the PSU for available energy and then adjust the power-limits of the GPU and CPU.
(Which is BTW not the TDP - the TDP is the thermal design power, which is not the same as the power-limit)
For me it would be definitely a USP that a workstation notebook can do this.

Actually your arguments rather sound like you want to tell what is not possible and complicated instead of finding solutions for these problems.

Finally: My general idea was not even about USB-C, it can be also with the slim-tip. Since I don't care from where the power is distributed.

Anyways: I think we will not find an agreement about this issue.

@maeffjus 

I fully agree with you. Almost the time, I use my P52 with 170W original charger but sometimes I have to go somewhere for a few days, I want to bring a smaller and lighter adapter, I will then use the laptop's battery and charge it while I'm at rest. The reduction in size and weight of luggage when traveling is a concern.and I think it is completely plausible. Lenovo may consider doing the same as Dell, which allows charging the laptop when turned off with a smaller adapter.

But Lenovo actually went 99.9% of the way.

- Laptop can determine what power adapter is connected, and complain that it's less than ideal (in various places, post-boot and pre-boot)

- Platform can work with power limits, and throttle itself. 

- There is even "airplaine in-seat power" mode, limiting consumption to 65W, fully supported https://support.lenovo.com/ca/en/solutions/ht062667 (but not in large P-series I think)

Lenovo could have easily implemented "If less than 135/170/230W adapter was connected, just run nVidia at very low frequency, and complain".

Hi maeffjus,

We may actually agree more than you think. I (wrongly!) assumed you might not know much about electronics. We both know how assumptions sometimes turn out, hopefully this one wasn't catastrophic ;-) I'm sorry. I won't oversimplify anything in this post, my point should be clearer.

First, I apologize for the confusing "we". I've often been on the receiving end of such conversations, and I sometimes (often?) forget that's not the case on this forum. No, I don't and haven't worked for Lenovo and never had an affiliation with them, but I did work in other computer shops. I will try not to do it again, and I did edit the previous post earlier because I had used "we" again.

For the next part, I'm going with some known facts:

- I agree that lugging around a big 170W adapter (~1.25" x 3" x 6", 21.5"³, 1.32lb) is annoying for a mobile device,

- That's 1/5th the weight of the P52 (or less),

- It's over the average power use of the laptop in most cases,

- The P52 must run fully loaded with it, but sometimes it cannot (170W not enough for all ports when loaded),

- The Slim Tip adapter power availability is known by the machine (ID pin with resistor),

- It's even worse with the newer models, some are using 230W adapter (~1" x 4" x 8", 29.5"³, 1.71lb),

Possibly facts (from memory, I read so many posts, I could have mixed a few):

P5x models previous to the P52 could:

- Use airplane power, (P52+ just ignores external power and runs on battery),

- Be powered from USB-C, even in a limited way,

And I thought that the P52 could run with a smaller PSU on Slim-tip, compensating with the battery. If it doesn't, well, that's sad! Anyway, Specs of smaller power adapters:

- 135W, ~1.25" x 2.5" x 5.75", 17.25"³, 1.1lb

- 90W, ~1.25" x 2" x 5", 11.53"³, 0.79lb (roughly half the size and 0.5lb less than the 170W one)

Now, I agree the electronic limitations are not unsurmountable. I think the CPU can be reconfigured (I know about TDP btw ;-) ), and likely the dGPU too. The EC should be capable to manage all this. Why Lenovo does not do so, yes, that's speculation. Call it an educated guess, but a guess. I'd like to know for sure. Certainly not easy to explain to someone not familiar with electronics.

One possibility is software: Microsoft has trouble delivering good Windows 10 updates, and their PC business is a mess. Combined with the 2-versions-a-year cycle, it causes much hair loss in IT departments. They keep moving the target for the sake of it. Just think about their power slider idea! Lenovo had something better, but not any more! Of course, that does not explain why the new Lenovo Vantage has so many missing features. At least, they made the old v3 available as the v20 "Enterprise" version!

Now, my understanding of USB-C PD is that it's primarily to power accessories. The P52 simply cannot feed 100W/port with the 170W adapter, but then, few will need to do so. As for why the P52 cannot take power IN, again, there is only speculation. I don't mind much as I don't have any USB-C devices anyway, but one day I will! My opinion might change then. Still, I chose to get the P52 instead of the P53 because of USB-C (I need USB3-A right now).

BTW, I'm sure you know Intel can strong-arm manufacturers, and they have made mistakes they tried to hide in the past. Up to recently, the P52 memory ran at 2400MHz instead of 2666MHZ, "Intel limitation" (now fixed in BIOS). There was this: Critical Intel Thunderbolt Software and Firmware Updates - ThinkPad , "These symptoms may occur after 6 to 12 months of typical usage". There was the "secret" recall of the Intel Atom C2000 processors with faulty clock outputs, used in network devices, which was under some kind of NDA. There was the flawed cable modem processor that caused huge latency spikes, as well as many others. How this ties in the P52? Maybe the missing PD-in is another "Intel limitation". But that is only speculation too!

I hope you can find a power source appropriate for your use case! You have the skills to jerry-rig an USB-C PD-in adapter board (quick search: https://www.electronics-lab.com/usb-pd-stand-alone-adapter-board-oxplot/) to Slim Tip. I'd try that, and you can test with the various resistor IDs to find one the P52 likes. Hopefully it will work with the 90W ID!

Good success!

Martin