Understanding Dell laptops and USB-C power sources

If it helps I can report back here once I have the laptop to confirm it’s pd, or for the integrity of the thread I can report it somewhere else. The Alienware M15 r3 and the M17 r3 which were just released a few months ago (July I believe) are the first laptops to support it. I would never attempt to game or do anything resource demanding with anything but the 240w power brick but if I can do basic word document typing and internet browsing with USB-C charging then that will be a game changer for me when I travel for work. I’ll know in the next few days if that is the case. 

This post was definitely useful. I have an older model XPS 15, a Precision 5540, and a new XPS 15 9500, and the differences between them is aggravating. I used to be able to charge my old XPS 15 at a full 90 Watts with 3rd party charges, then that functionality disappeared with a BIOS update. Now, my new XPS 15 supports charging at 90 Watts from that same brick, but my Precision 5540 doesn't. If anyone knows why Dell put this restriction in place it would certainly be helpful, say if they only support obscure USB-C PD configurations.

@proprietarilyfubar  The XPS 15 models support pulling 130W over USB-C/TB3 from Dell docks, but Dell's 130W USB-C power adapter wasn't created until Dell launched the XPS 15 9575 2-in-1, since that system didn't have a "traditional" AC adapter connector.  So the XPS 15 9570 might not actually support pulling 130W from that particular adapter.  I know for sure that older XPS 15s don't even though they also support 130W over USB-C/TB3 from Dell docks.  If you want to check, go into your BIOS and look at the Battery Information section.  In there you'll see the wattage of the connected power source.  Does your system show 130W when you have that adapter connected, or is it treating it as a lower wattage source?

I have bought a 130W Dell USB-C Charger, which I'm using with my XPS 15 9570 (i9-8950HK + 1050 TI Max-Q). I have a strong feeling that operation is much slower compared to using the regular power charger. Especially when I'm maxing out the GPU by playing games. 

@jphughan Any updates on this topic on an XPS 17? Would love to see an update (similar to XPS 15 being able to pull out 90W power from a 3rd party charger). 

@Lokdoi  I haven’t seen anything one way or the other about how the XPS 17 9700 behaves with third-party USB-C chargers. Sorry!

Great write up, thank you!

I've found myself on this thread with an XPS15 9560 with discreet GPU, so the 130w adaptor.

My issue is that the adaptor trips in seat power in nearly all aircraft, and as I like to edit on flights, it's a real issue for work.

If I get a 90w USB-C adaptor (though my laptop might only allow a 65w draw?) would that still help the laptop while plugged in for a longer window of usage, or would it end up being a cycle of 1h work, shut, allow to charge, boot.

I realise editing is going to drain the battery with anything less than 130w, but if it buys me another hour of editing before having to shut for charging, that seems like a good investment to me.

I hope Dell are paying you for this

I've just ordered that adaptor, and I'm due to fly again in a few weeks so I'll be sure to report back!

Thank you for taking your time to write up the OG post, really useful (and interesting)

@Tyre Reviews  I haven't used an XPS 15 9560 with a 65W power source (or effectively 65W power source) for any meaningful period.  But I remember reading a review of one of Dell's Power Companion models, which is essentially a power bank for laptops.  It operates as a 65W power source.  And the review noted that the system's performance throttled when connected to that undersized power source, and also that under very heavy load, the system would still exhibit a net drain on the battery even with the reduced performance.  The takeaway was that if you're going to run a heavy workload, you'll want to connect the power bank early to slow down your rate of discharge, because if you wait until your battery is almost dead before plugging in the power bank and then continue running a heavy load, the system will die.  But if you can plan for that and the reduced performance isn't a dealbreaker (or is at least less of a problem than tripping the airline outlet), then it may be worth considering.  I have this 90W dual port USB-C port adapter, which I like because it can split power across its ports in multiple ways namely 90/0, 60/30, and 45/45.  Good luck!

@Tyre Reviews  By the way, I don't know if you'd have a use for this, but I also own this power bank.  Its 20,000 mAh / 72.6 Whr capacity is enough to charge phones multiple times over and even exceeds the capacity of some laptop batteries.  And unlike most high capacity power banks that are only designed to provide enough wattage output to charge devices like phones and tablets, this one supports up to 60W output via USB-C, which is enough to run most laptops at least reasonably.  And yet it's small enough to be carried around if needed, even in your pocket if you have large pockets.  I've been quite happy with it.

@Tyre Reviews  Dell’s specs for the XPS 15 9560 indicate that it came with either a 56 WHr or 97 WHr battery, depending on whether the system came equipped with a 2.5” drive. Otherwise, the space that would have been occupied by that drive went toward the larger battery. So that RAVPower power bank sits roughly in the middle of those two figures. Of course energy transfer is never 100% efficient, but I’d estimate that you’d get maybe a full recharge of the smaller battery and a 60% recharge of the larger battery.

If you want to increase the longevity of batteries that spend most of their time on AC, as mine do, check out my post in this thread. The XPS 15 9560 supports the options I describe there.

Thanks for the power bank link, that's interesting. I wonder if it would give my laptop a full charge or not.

It's probably time I replaced the battery inside too, it's nearly 4 years old and has sat on power most of it's life so won't be super healthy.

Well, I read, I have a precision 3551, with charger usb 130watt, yes is the default charger, just today I looks 20Vx6,5A=130Watt, or 5V*1A=5Watt.  A joke? 

I was wondering if I buy a normal charger works 130Watt, 19,5Vx 6,6A with 7.4mm. theoretically I thin yes.

I care little or nothing about charging via usb c, indeed perhaps in some cases it is a boomerang.

I don't want to occupy the usb c with the charger, and I think the less I use it the better, the less it can be damaged.

Occasionally, usb c, it can be used as a battery charger, but since there is the classic power port it is better to use that.

The classic power port is better proven for charging.

Honestly I have seen the wd19tb docking stations, with a 180watt (or 130Watt) power supply,

I do not understand, if The wd19tb work with the two laptop that I have : the Latitude 5300 and the Precision 3551. On one I have the lightning bolt symbol that would indicate thunderbolts, on the 5300 dp only, thunderbolts was optional. Any help in this regard?

@flyblu  Wow, I remember reading that the Dell 130W USB-C charger only supported 20V and 5V output (which is lame on its own), but it really only supports 1A output at 5V??  That's ridiculous.  Lenovo's USB-C chargers support 5V, 9V, 15V, and 20V, and they support up to the 3A max for the first 3 voltages, and then up to whatever amperage is necessary to achieve their total wattage on 20V.

But yes, given that the Precision 3551 has a 7.4mm barrel connector, I would absolutely expect that you could buy a "traditional" 130W Dell charger with a barrel connector and be fine.  I've never seen a report of a Dell laptop limiting power input on its barrel charger port to an amount below what the system is designed to use.  So for example, if you have a 130W system like that, the system wouldn't limit itself to 90W on its barrel connector.  On the other end, it won't benefit from plugging a higher wattage charger into that connector, but it would still be able to use it.

The WD19TB supports Thunderbolt 3 if it's supported on the attached system, but it can also run in USB-C backward compatibility mode for non-Thunderbolt systems.  But in that mode, it has reduced functionality equivalent to a regular WD19.  That means that the "downstream TB3" port at the edge of the dock won't be usable, and your video bandwidth will be reduced.  The Latitude 5300 supports DisplayPort 1.2 over USB-C, which means that when the WD19TB is in USB-C backward compatibility mode, your display setup would be limited to either dual displays up to 1920x1200 each or a single display up to QHD/1440p (or 4K but only at 30 Hz rather than the normal 60 Hz).  Thunderbolt mode with the Precision 3551, which also uses DP 1.2 rather than 1.4, would allow dual displays up to 4K 60 Hz each or triple displays up to QHD/1440p each.  But of course if you plan to mix a Thunderbolt and non-Thunderbolt system, you'd pretty much have to limit your display setup to something that would work with both systems, unless maybe you wanted to disconnect one display or run lower resolutions/refresh rates on the non-Thunderbolt system.