The monitor comes with a USB-C port that sends power as well as image. But it's unclear to me:

  1. What's the wattage it sends?
  2. Is that enough to charge an MBP that's in use?

Your model MBP ships with an Apple 87W USB-C Power Adapter and USB-C Charge Cable. However, you don't need the full 87W in order to be able to charge the MBP. Apple's adapter is designed to provide an ideal amount of power in order to both use the MBP and charge it at a certain rate.

You can use lower rated power adapters, but depending on the quality and actual power output, they may not last long if used continuously for charging the MBP, or they may not be able to charge it while it's operational. Obviously, I can't cover all scenarios here.

However, in terms of the U2419HC Dell UltraSharp 24 USB-C Monitor, one of the USB downstream ports does provide up to 65W of power. By way of comparison, Apple typically provides:

  • 30W adapters for their MacBooks and MacBook Airs
  • 61W adapters for their 13" MacBook Pros
  • 87 W adapters for their 15" MacBook Pros

In a nutshell, what this means is that you will be able to use the U2419HC Dell Monitor and also charge your MBP at the same time, but it won't charge your MBP as fast as your Apple 87W USB-C Power Adapter will.

How fast it will charge your MBP will also depend on its usage - if you're just doing some word processing it'll charge faster than it will if you're rendering videos or playing graphics intensive games, so that may factor into your considerations. However, for most people most of the time, this monitor will work fine as a display and charging source.

Since you're interested in understanding the rate of charge and discharge of your MacBook Pro, I thought I'd recommend you download and try coconutBattery. It provides a whole heap of information that you'll find useful, and from memory includes both Discharging with and Charging with measurements in watts (obviously, only one is displayed at a time since your device can't do both simultaneously).

Also, I should point out that macOS also provides a great deal of information. Follow these steps:

  1. Got to Apple > About This Mac

  2. Click on the System Report... button

  3. In the left pane under the Hardware heading, select Power (it's about 2/3 of the way down)

  4. On the right-hand side, scroll down to view the AC Charger Information

  5. This will show you whether it's connected to a charger, the amount of wattage it's receiving, and if it's currently charging or not

Note: I am not affiliated with coconutBattery in any way.

  • Thank you for a very detailed answer. I've marked it as correct, though one thing that would improve it is if you could point to a resource which would show me how much power I'm using at the moment. – Mystic Dec 11 '18 at 14:56
  • When you say "show me how much power I'm using at the moment" what do you mean exactly? – Monomeeth Dec 11 '18 at 22:10
  • I'm asking for information on how can I know whether I'm getting a net charge from the monitor or just maintaining power levels? Is there a case where I'm still draining the battery despite being plugged in? – Mystic Dec 14 '18 at 3:57
  • @Mystic For most people most of the time you'd still be getting a net charge. Even for the edge case in the low minority of users, it's not likely to be an issue very often because computers aren't typically under a heavy CPU/GPU burden for much of the time. Can I ask what you use your MBP for? Unless your MBP spends a lot of time rendering video, animation, audio or software - or you spend a lot of time playing graphics intensive games, then I can't see this being a problem for you. – Monomeeth Dec 14 '18 at 6:48
  • @Mystic I've updated my answer to add info on coconutBattery. I think this may be something you're interested in. I've also explained how you can view the System Report within macOS and access power info from that. However, these options only show you the current status of what's going on, so it won't help you decide on whether to buy the U2419HC Dell Monitor - although I suppose it could help you decide if you want to keep it. All the best with it. :) – Monomeeth Dec 14 '18 at 8:24

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