Pls help me clear up USB-c mess

hiii i’m looking to buy an HP AC adapter 65W USB-C LC
it’s just a basic adapter which works over usb-c, but it has the marking of LC which means low current maybe? i wonder if it would be all fine to use it with an asus laptop, as i dont wanna carry my big adapter everywhere. my laptop has an USB-C port with 65w PD
( i’m a student and this is a cheapest usb-c adapter with these specs that’s why i would want to buy this)
can you please help if it would be alright going with this

my laptop has these requirements for USB-C charging:
USB Power Delivery power adapter* information:
• Input voltage: 100-240Vac
• Input frequency: 50-60Hz
• Rating output current: 3.25A (65W)
• Rating output voltage: 20V

So is that LC marking fine or should i pass on that?

Do you have a phone charger that can put out 65W ? they are pretty common these days and would work in place of that HP adapter.

hiii nope sadly, it’s not very common in my area,
i had previously a 65w charger but it broke down, still have one C-C cable for it i bought but
i dont have a charger that has an USB-C port xd

It should be fine with an ASUS laptop if thats your cheapest option. I would try maybe some 2nd hand stores if they exist / e cycling. Might be able to find something cheaper .

Depends on the voltage expectation of your laptop. Can you figure out what voltage it expects from the charge port?
If it supports 20v charging, then 20v 65w charger will be 3.25A. The charger you’re looking at may not support going much above 3.25A at lower voltages, assuming it can even negotiate those at all, so make sure your laptop is happy at 20v charging.

yes, i dont need more, as my laptop only supports 65w
here’s an image from the manufacturer’s manual:

well i think i should go with these specs

1 Like

yeah, i thought about that, but i rather get something with at least a little warranty, as i had bad luck with some second hand tech

USB PD negotiates over the cable what voltage and current limits it should run at, before starting the >5v delivery.

This means that if the adapter is capable of delivering at least the laptop’s requirements, it will work.

1 Like

I did not realize USB-C powered laptops ran at 20v, I would have just assumed the same 5v. Do they HAVE to run at 20v, or can you still plug them in to a USB cable that’s powered off of some 5V source (obviously at lower power capability)?

well, if you run on 5V it wont gona take more than 1A probably
which basicaly limits this to 5W -and this is very for all current laptops i think
tho i wonder if i connect 2 laptops, where both have usb-pd, and one charges another then can the host laptop provide higher voltages too or it wont?

Lots of USB C laptops don’t have the boost converter to take in 5v (or anything below 20v, for that matter) and charge the battery. Some do though, like the framework. I’ve trickle charged my framework off a 5v2a USB C before, but it took ages. 10w is not a quick charge haha.

That said, the USB C PD spec is 1-3(or 5) amps, and 5-20v. There is a new spec coming out and some companies have “addons” that allow you to go beyond that. For example, the new spec allows up to 50v, and IIRC, certain Dell adapters allow for up to 7A or 140w.

What it comes down to is if the laptop has the internal circuitry to take in a varying voltage. Most don’t, because of the power required to operate them, the manufacturers assume no use case for low voltage charging circumstances.

This is another “it depends” answer. If the source laptop has a power delivery “source” circuit, it can deliver whatever that specific circuitry is capable of. Often times, this will be 15v3a or 20v3a. Very rarely will you see a computer (desktop or laptop) that can output 5a. 5a requires an electronic tag in the cable you’re using, that indicates the cable is capable of carrying that current. 3a is a standard and universal limit, but 5a requires beefier wires.


pretty sure LC just means long cable

65w has to be delivered over 20v as per spec so you should be fine

1 Like