[Linux-aus] USB-C chargers

Adam Nielsen a.nielsen at shikadi.net
Mon Nov 28 23:39:59 AEDT 2022

> I've attached a message I get from KDE when I hover the mouse over the battery 
> icon, it says "The power supply is not powerful enough to charge the battery".
> My problem is that I don't know enough about this topic to know what to look 
> for.

It would be interesting to see what a USB power monitor says in this
situation.  I guess the laptop needs more than the 1.5 A the charger
can deliver.

> I know the USB-C cables work for "fast charge" of phones.  I don't know if 
> that means much, probably not.

"Fast charge" usually refers to various proprietary standards that came
about before USB-PD was designed in an attempt to replace them all with
a vendor-agnostic solution.  Fast charge usually doesn't need any extra
signal wires in the cable beyond what came with USB 2.0, but it has
various other limitations (requiring certified cables to get peak power,
not allowing data and charging at the same time, etc.)

> Thanks for the suggestion!  I sent the URL to a friend who's really good at 
> buying stuff from China.

For the record, Aliexpress is very straightforward to use.  You just
have to put in the effort to pick out the fake products from the real
ones, and test everything that gets delivered so you can claim a refund
if you were sent a lesser version of what was advertised.  Oh and be
prepared to wait 2-6 weeks for delivery.  But they have things you
can't buy anywhere else.

> The power monitor has a male USB-C connector to go to the PSU and a female one 
> to go to the device being charged.  So to put it between a laptop and a laptop 
> PSU I'll need 2 adaptors.

If you get adapters, remember they are just as suspect as USB-C cables.
So you'll need to independently verify that each adapter correctly
works for USB-PD before you rely on it when testing other devices.

> > So why were we trying to get a low power charger?  I don't find the Thinkpad
> > one very bulky... is it?  
> It's not that big, but when you already have an inverter for powering things 
> in a car it adds up.  Also I can fit my Thinkpad in my jacket pocket and a 
> small charger takes less space in one of my other pockets.

I assume you've looked at USB-C PD car chargers?  A quick Google for
"thinkpad car charger" shows a few that run off 12 V and can deliver 90
watts which should have no trouble charging any USB-C laptop, and as a
bonus, they don't need the inverter running as they run off 12 V
directly.  But they probably aren't any physically smaller than what
you have now, although maybe you can leave it in the car permanently
instead of having to carry it with you.


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