USB Type C charging question

Leo did an “Ask the Tech Guy” show about Type C charging recently - but even he admitted that it was complicated…

I had a quick question… I have two Chromebooks with 45W type C charging plugs. Both are HP Chromebooks, and they have the giant brick in the middle of the cable - like most laptop plugs do…

And, I have a Samsung S8 cell phone that uses Type C, but it appears to be 15 watts (according to what I found on Google just now - I don’t have the charger in front of me)…

I have made sure not to use the phone charger on the laptop, or the laptop charger on the phone. The phone charger likely would not hurt the laptop - it just would provide less power. But, I suspect that the laptop charger might possibly damage the phone…

Anyway, I have made no efforts or attempts to try to cross the chargers. However, my 12 year old son has wanted to do this several time with his laptop and cell phone - and I told him that I thought he might regret plugging in his Huawei cell phone into his 45W Chromebook charger.

This page seems to suggest it might be okay on my Samsung, but I am not sure about his phone:

What is the opinion here? For now, I have tried to stick with the appropriate wattage chargers for their particular device. I have done some Google searching, and I find arguments on both sides of the issue…

I’m no expert but just because something can supply 45w doesn’t mean that it will automatically give out 45w. The wall socket that you plugged the charger into it is capable of outputting well over 2000w but that doesn’t blow your laptop charger up.

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The USBPD spec says that devices are supposed to be able to negotiate the proper power for their rating -

The question then is whether or not your device abides by the spec. One example of a device that absolutely does NOT is the Nintendo Switch.


Most technology today has tech built into it to determine if what is plugged into it is okay or not. Sometimes plugging a high watt charger into the phone will result in nothing because the tech refuses the connection other times it will simply limit the amount of charge that can be delivered to the battery. I would not be to worried about plugging a high watt charger into a device unless it is some sort of cheap Chinese device that may not have the tech to do this. The galaxy S8 will limit it to the max 15w indicated your sons phone will most likely limit to the max wattage it will accept.

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Yes, do not use a non-nintendo charger on your switch. It’s probably okay to use a matching watt charger when its off but especially avoid this when playing the switch.

They need to come out with a new iteration where they add bluetooth headphone support, better charging capabilities and for the love of god fix those joycons.


You probably don’t want to mix them up unless you had not other choice. Under-powering one thing and over-powering the other will probably work if all devices follow the specs, but of course they were not tested that way by their manufacturers, so you risk unexpected results. In particular, if the phone is not well designed but chooses to attempt to charge faster than it should, it may work, and you may get a faster charge, but you may be harming the battery life significantly from heat.

That is definitely always a risk when dealing with batteries but I can tell you that I work with phones and laptops and tablets and chrome books daily and I have plugged them into multiple different types of chargers and never had an issue and have left them plugged up for days or weeks. I mean there are Dell USB-C docking stations that you can plug a Samsung galaxy S8 into and get Samsung Dex functioning even though the dock is a 45 watt dock it works just fine and if you look it up in the tech specs it actually tells you that it is compatible for this use but that the phone will only charge at a max of 15 watts. But some technology makers put cheap tech or non at all in their technology so yes you do have to be careful in that aspect.

Edit: I will say though it probably isn’t advisable to plug in tech into the wrong chargers when you have the right chargers available.

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You would be perfectly safe using the 45w charger on the Huawei phone IF they both follow the USB-PD spec as noted in several other comments. You’d have to look up your sons phone model and the charger (maybe marked on it).

This ”downward wattage” compatibility is what the PD spec is all about. The problem is determining whether the devices comply with the spec. As an example, I have no fear about using a 30W or 45W MacBook USB-C charger with my iPhone or iPad because they adhere to the USB-PD spec. (The other way around would likely be bad or just bit work.)

Many devices ship with chargers that are lower in Wattage than the device can handle, likely for the manufacturer to save $$. With today’s standards you cannot make the blanket statement that the included charger is ALWAYS the best option. In the end, better safe than sorry tho.


That was my opinion when making my post

Power is very complicated. There are lots of variables, I think it’s also about the voltage and amperage.

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