Understanding Dell laptops and USB-C power sources

@Broccoli Cobalt  Glad you found my post useful!

If your laptops are designed for a 65W power source, then you shouldn't be considering USB-C displays that only provide 45W unless you also plan to keep the laptop's AC adapter directly attached as well.  Otherwise, while you won't DAMAGE anything by giving your laptop an undersized power source, you will create a subpar experience for your users.  First, the laptop will display a warning about an undersized power source every time it boots while connected to one, which will be an annoyance.  But worse, if a laptop designed for a 65W power source is only fed 45W, the laptop will try to operate within that reduced power budget by doing things like reducing its battery charging speed and reducing its CPU and GPU performance.

There are several USB-C displays on the market now that provide 65W or even 90W (although as mentioned above, as of this writing you won't get more than 65W over USB-C to a Dell system unless it's from a Dell source).  I would recommend that you consider one of those options.  Also keep in mind the note above about the USB-C cable coming into play if you want to go above 60W.  If the displays you buy supply more than 60W and come with a USB-C cable, then it's a safe bet that the included cable will be rated for up to 100W.  But if you'll be buying USB-C cables separately, you'd want a USB-C cable that supported DisplayPort Alt Mode for video and USB PD up to 100W, like this one.

I'm considering purchasing a large quantity of non-Dell USB-C monitors for my organization; however, the power delivery is only 45W while our standard issue Latitude 7390 2-in-1 laptops draw 65W. Your article is super helpful but it's still unclear to me if the 45W over USB-C will charge our laptops or if the monitors are incompatible or, worse, potentially damaging to the laptops. Would you clarify?

@Broccoli Cobalt  CORRECTION!  I initially linked to the wrong type of example cable in my post above.  I've edited that post to link to the correct product.

@Smeg Head  This thread is purely about how Dell laptops handle USB-C power sources, so I'm not sure why you're posting about docking stations and "mini-dock" products here.  If you want a "mini-dock" product recommendation for your needs, then I would suggest that you create a new thread of your own that describes what system model you have and what device(s) you want to be able to attach through this device.  You'll get more visibility for your question and you'll avoid taking other people's existing threads off-topic.

@Smeg Head  Actually I just re-read your post and realized the only part you were asking about was the power source.  In that case, it seems the Latitude 3400 is designed for a 65W power source.  But if you'll be connecting it through a mini-dock, make sure that it supports providing at least that much to the attached system.  Some only pass through at most 60W because you need different cabling to exceed 60W, and some mini-docks might not incorporate that for their connection to the system.  Also be aware that mini-docks tend to "skim" some power from the attached power source when one is available in order to run their internal electronics and provide power to USB peripherals that are attached to them.  When the mini-dock does NOT have a power source attached, it would draw from the system, but the dock can't provide power to the attached system and draw from it at the same time.  The end result is that plugging a 65W power source into a mini-dock does not necessarily mean that the system will see a 65W power source.  It might see a 45-55W source instead.  So if you want to minimize the chances of warnings about a "Slow USB charger", you might want to look at a 90W power source to make sure you have enough capacity to pass through 65W even after whatever the mini-dock skims from that source.

And then you'll need a USB-C cable rated for up to 100W Power Delivery because most USB-C cables are only rated for up to 60W, and if you use a 60W cable, then that's all you'll ever get even if the power source could otherwise provide more and the device you're trying to power would accept more.

Well, I tell you what...I bought my system...and I bought an additional power cord/charger/etc. Neither worked well from day one. I kept getting messages that said I was using a charger that didn't have enough power and that my laptop would drain battery power faster than it could charge! I was using Dell chargers! The one that came with it and the same exact one they sold me. I've replaced both...twice!!!

Seems to be a Dell laptop and charger problem.

@jphughan Thank you. The one device I linked to seems to be 100 watts and it lists the Mac book Pro and some 15" laptops, and Dell Inspiron and Latitude laptops. The second quotes 60 watts output with the reduction due to the what the dock uses. If I buy a charger which delivers something over say 70 watts, that should then supply the dock and the laptop whichever I use (maybe better to utilise the higher wattage and buy a 90 + charger?), my query was more will a generic charger work, and Dell laptops don't require a Dell dock, it's a standard they should all adhere to?

@Smeg Head  Dell laptops that support being charged over USB-C support that using the industry wide USB Power Delivery standard.  But it seems that they do place limits on third party USB-C power sources, for reasons that aren't clear.  But yes, they do work, at least up to 65W (or the max that the system uses if lower, such as the XPS 13 that only uses 45W anyway).  I personally have USB-C power sources from Anker, Nekteck, and Satechi with outputs ranging fro 60-90W, and my various Dell laptops work fine with all of them -- again, up to either 65W, the charger's max output, or the system's max draw, whichever is lowest.

As to the devices you linked, the one that only passes up to 60W might not be because it's account for skimming losses from a higher wattage source.  60W is a fairly common maximum limit to see with USB-C cables because it corresponds to 20V (current max of the USB PD spec) at 3 amps.  Currently, there are two "classes" of USB-C cables, namely those rated for up to 3 amps (60W) and those rated for up to 5 amps (100W).  Cables that support the latter need to include an "e-marker" chip to advertise that capability.  So I suspect that the 60W limit in the case of that adapter relates to its permanently attached cable.

As for a Dell dock, certain Dell systems like the XPS 15 are designed for 130W power sources, and Dell did something proprietary with systems like that as well as certain docks in order to send that over USB-C/TB3, stretching past the 100W max of the official USB PD spec.  So if you want that, you'd have to use a Dell dock.  And then Dell also has a WD19DC dock that plugs into two USB-C connectors on a system in order to provide up to 210W in order to properly support laptops that have even higher power requirements.

Hi there,

A GREAT piece of information and well written – MANY THANKS.

I will be purchasing the new Dell XPS 13” clamshell later this year when Dell releases it with the new Intel 11th Gen CPU “Tiger Lake” assuming Dell go with Intel !!!

Like the current model Dell XPS, I am also assuming it will come with 2 x Type-C Thunderbolt ports and the device will be rated at 45 watts.

I am looking for two separate Hub/Docking solutions and one additional power supply.

Solution1 - An immediate hub purchase to go with the new XPS. This hub needs to connect all the peripherals listed below and would also be used as a travel solution. This solution would be a temporary solution until Thunderbolt 4 Hub/Docking Stations will hit the market place sometime later.

Solution 2 - Thunderbolt 4 Hub/Docking station when they become available. This is mostly likely to be the Dell WD19TB, but a Thunderbolt 4 version. This hub needs to connect all the peripherals listed below

Regarding Solution 1:  When writing this, what seems to best suit my requirements is an “Anker 8 in 1, 10Gbps Data Hub Model A8383”.   However its power specifications states:  “The USB-C port supports pass-through charging up to 100W (minus 15W for operation), allowing you to charge up your laptop at high-speed while retaining full function of the hub’s other ports.” 

Peripherals to be Connected: Other devices to be run through the “Anker 8 in 1, 10Gbps Data Hub Model A8383” that would be connected to the new XPS 13” “Tiger Lake” processor include:

• Dell Monitor U2718Q – External screen connected full time via a DP1.4 or HDMI connector.
• Samsung Galaxy S10 5G phone – Occasional syncing with Outlook on XPS. Use USB Type-C connector.
• External hard drives for backup purposes – 3.0 Micro B connector. Might use “the other XPS TB4” port.
• USB Memory sticks – USB Type-A connector
• SD Card
• Ethernet – RJ45 connector. Full time Ethernet cable connection to modem/router.
• Dell Sound bar AC511M, CN-0XFDH2-71623-93B-2195 – USB Type-A. Full time connection

So based on the above power specification and your great article and wanting to buy an additional power supply to be used with the XPS 13” connected to the  “Anker 8 in 1”, what Dell power supply should I buy?

1) Dell USB-C Power Adapter Plus Slim – 45-Watt with USB port. Manufacturer Part Y91PF, Dell Part 492-BBWZ,    Dell Order Code P4516wsap

2) Dell Adapter 65-Watt Type-C with 1M Power Cord, Cus Kit Manufacturer Part 9FNYW,  Dell Part 492-BCBI,   Order Code 492-Bcbi | Dell

3) Dell USB-C Power Adapter Plus 90- Watt - PA901C,   Manufacturer Part 6WX94,   Dell Part 450-AJML

4) Some other Dell USB-C Power Adapter

I hope I have given you enough information. Please let me know if you require other details.

Very much looking forward to your recommendations and please do correct any of my incorrect understanding.

Mark Dent

@shiraz2many  Glad you found my post useful, and thanks for the kind words!

In terms of your travel solution, right off the bat if you plan to run a 4K 60 Hz display through a travel hub, you have to make sure the hub itself supports DisplayPort 1.3 or better over USB-C to get that signal out of the system. Most products on the market right now only support DP 1.2, which will limit you to 4K 30 Hz on displays attached through the hub, even if your system supports DP 1.4. The Dell DA300 adapter supports DP 1.3, but I don’t think it has enough other connectivity for your purposes. (Or you could connect the display directly to one of the other USB-C/TB3 ports on the system.)

In terms of power sources, the fact that you’ll be using a system that will likely only require 45W definitely simplifies things, since even if the hub “skims” 15W for itself, that means you still only need 60W total from the source. But since USB-C is only going to become more universal as a power delivery mechanism, I personally would go with the highest wattage power source you can find that is still an acceptable size and cost for you. And there’s no real reason to limit yourself to Dell here, since USB Power Delivery is an industry standard. If you needed 130W over USB-C, then you’d be stuck with Dell, but ironically their 130W adapter isn’t great as a universal option since it only supports 5V and 20V output, not 9V and 15V as are commonly used by some devices for fast charging.

I personally just bought a RAVPower 90W dual port USB-C charger here. It uses new GaN (gallium nitride) technology that allows it to be much smaller than traditional power sources of the same wattage, and it wasn’t very expensive. It can also split its 90W output across its two ports in multiple ways, namely 90/0, 60/30, and 45/45, so it’s a great all purpose charger.

And if you want a great multi-purpose charger for travel (when we can do that again...), look at the Satechi 75W Dual Type-C travel charger here or the 108W Pro version here. You get a 60 or 90W Type-C port, an 18W Type-C port (enough to fast charge an iPhone) and two USB-A ports with 10W total max output. That single charger covers me when I travel since I can charge my laptop, phone, watch, and one other thing all from that single device. And the “one other thing” is either a USB power bank or headphones, neither of which need to be charged every night like the other 3 devices. It is awesome.

Hi there,

New to all this so not sure how to address people (sorry)

 Re Travel – Understand/agree with your comments but this is not an issue as for when I am travelling I use the XPS’s screen

• Re Power Sources - Understand/agree with your comments – Thank you.

 Kind Regards 

Mark Dent

This is a great write up and addressed a number of my questions regarding dell's handling of USB-C charging. I am curious to know if you're aware of whether or not the 65w max pd with third party devices affects all of their laptops that are rated for higher pd or if there are only some. I just purchased an alienware laptop which now supports USB-C charging but dell makes no mention of its rated pd. Obviously if I can I'd like to get as close to 100w if possible but if it's going to be hampered by the same 65w limitation then there's no reason to spend extra money. Thanks for your help! 

@cshelt  Happy to help, glad you found it useful!  The only system I've seen reports of pulling higher wattage from third party USB-C sources has been the XPS 15 9500, where users have confirmed being able to use up to 90W.  I'm not sure if 100W would be possible since I don't remember seeing anybody test a 100W source.  I would also bet that the XPS 17 9700 would probably have the same charging limitations as the XPS 15 9500, but I can't know that for sure.  And I certainly hope that this is a sign of things to come with Dell laptops overall, since this 65W limit seems arbitrary and certainly aggravating.  As for your Alienware system, I'm actually surprised it supports charging via USB-C at all, given that all modern Alienware systems to my knowledge are designed for WELL more than 100W, or even the 130W that Dell stretched the spec to deliver over USB-C/TB3 with certain systems.  I know that at least the early Alienware systems that incorporated USB-C/TB3 didn't support charging from that port at all, I figured for this reason.  But even if that has changed, I wouldn't recommend using a USB-C power source while actively using the system.  If you have an Alienware system designed for 180W, 240W, 330W, or the Area-51M that's designed to have (I think?) both 330W and 180W power supplies connected simultaneously for max performance, then even at 100W you'll be giving your system far less power than it's designed to have available, so you'll likely see slower battery charging, reduced performance, and possibly continued battery drain.  If you'd only want to use that type of power source to charge the system overnight while it's asleep or powered off, then that would very likely be fine, but I wouldn't rely on it for anything beyond that.  Sorry I don't have more detailed information for you though!