Precision 3551 charger and Thunderbolt

Question

I have a dell precision 3551 and upon purchase the configurator obliged me to take the 130w usb c charger (he said it was for the graphics card). So i have only one usb c port (thunderbolt) and i'm forced to use it for charger but i have also the barrel 7.4 mm AC port without any compatible charger. If I buy a 90W charger with 7.4 mm barrel (which the online configurator did not let me take) can I use it in order to free the usb c port? Is there any other accessory that allows me to free the usb c port? Is there any other accessory that allows me to free the usb c port or the only option are the dock stations?

The configuration: i7-10850H, 32 GB RAM, 1TB SSD M.2, Quadro P620, FHD display.

Thanks.

jphughan · Accepted Answer

@alessandrom  Looking at the full specs more closely, it looks like this system can be ordered with an NVIDIA GPU or only with an Intel GPU. That is probably the difference in power requirements, where Intel-only systems require 90W and systems with NVIDIA GPUs require 130W. It’s possible that at least in your region, 90W systems only come with 7.4 mm adapters and 130W systems only come with USB-C adapters. I don’t know why Dell would do that, but the fact remains that if your system is designed for 130W, then it will need a 130W adapter for optimal functionality regardless of which adapter type you use. It’s not like USB-C is incredibly inefficient and therefore you only need 130W when using a USB-C power source, while a 7.4 mm source means 90W is sufficient. That’s not how it works. It’s possible that Dell shipped the system with a 130W source even though it only requires 90W, but I’ve never seen that done. So again, if you want to use a 7.4 mm source, I would strongly recommend that you get a 130W version. Even if the Precision 3551 can be ordered with a 90W 7.4 mm adapter, the fact that you couldn’t choose that on YOUR order makes me think that your specific configuration would NOT work properly on a 90W source. Of course that doesn’t answer why Dell doesn’t just offer a 130W 7.4 mm adapter option with the system itself, but I can’t speak to that.

DELL-Cares · Answer

Thank you! We have received the required details. We will work towards a resolution via private messages to ensure the security of your information. In the meanwhile, you may receive assistance or suggestions from the community members as well.

jphughan · Answer

@alessandrom If your system is designed for 130W, then get a 130W 7.4 mm charger, not a 90W. Dell 130W chargers with 7.4 mm barrel tips have existed for over a decade, so they’re not difficult to find, and that way you’ll avoid issues such as slow battery charging and reduced performance by running your system from an undersized power source. But otherwise, yes getting that charger would free up your USB-C/TB3 port for something else. I’m surprised they forced you to take a USB-C charger with a system that only had one of those ports. Normally they give you a choice, at least in the US.

You could also get a Dell dock that supported providing 130W over USB-C/TB3. The Dell WD19 will do that when equipped with a 180W power adapter (the WD19 130W only passes 90W through), and the WD19TB will also pass 130W since it comes standard with a 180W adapter.

alessandrom · Answer

Thanks @jphughan , the system is designed for both 90W barrel charger and 130W type C chargers and it is written in the user manual (attached Italian page). This is why I doubted that the 90W charger could create problems or reduce the performance. This only because on the online configurator I was forced to choose the 130W usb c!

jphughan · Answer

@alessandrom  That doesn’t make sense at all. Dell makes 90W USB-C chargers, so if the system was only designed for 90W, I don’t know why they would have required you to get a 130W version. That might be an error in the specs on that page. Dell has absolutely had errors in their specs before, which I know because I’ve submitted them to their Documentation team and they’ve corrected them. I would suggest getting a 130W 7.4 mm charger just to be safe. They’re not much larger or more expensive, and if your system doesn’t need the extra power, then it won’t do any damage. If however you get a 90W charger and see a warning at boot about an undersized power source, then you’ll have to get a 130W charger for optimal performance.

FGPizz · Answer

What about buying an adapter USB-C female INPUT TO round barrell OUTPUT? Is it a good idea? Which kind of barrell OUTPUT? 7.4 mm? Male or female?

jphughan · Answer

@FGPizz  I’ve seen the opposite, meaning female barrel input to male USB-C, but not the adapter you're describing. However, with either type of adapter, you’d have to check the maximum wattage the adapter will pass through. Even 130W is already above the 100W max of the official USB PD spec. Dell did something proprietary on SOME of their products to support running 130W over USB-C/TB3, but you won’t find that everywhere. I think Dell’s own female barrel to male USB-C adapter is limited to 65W, if memory serves. So even if you can find an adapter that goes in the direction you want based on the type of power source and system you have, it might not pass through enough power to run the system properly.

Precision Mobile Workstations

Precision 3551 charger and Thunderbolt

Was this post helpful?