USB C mysteries

Off-Topic (In the weeds/General Discussion)
1

I have a USB C lap top charger. IE it is used to charge lap tops via a USB C connection.

Actually I have two of these. I use the spare one to charge my cell phone & my bluetooth headset (it’s faster than the wallwart chargers).

I also have a Snug power bank that I can use to charge cell phones (USB C or micro-USB), tablets, kindles, headset etc.

Now I bought my wife a very handy portable fan that can easily be placed where ever she is sitting and which also has a built in light. So this is very handy for her when she is knitting. It has a USB C port for charging.

Last night it ran out of battery. No problem… I’ll just use the lap top charger.

Only thing is it didn’t charge. No lights came on to indicate charging, and after an hour the batteries had no charge in them.

Puzzled I used the power bank. Straight away the charge light comes on. After 10 minutes or so the power bank is still on and the SOC display is going down. Eventually the fan was completely charged and the power bank then turned off.

So when is USB C not USB C?

2

Your mistake is to assume a laptop charger is just a laptop charger. They have a bunch of extra circuitries that does communication over the usb-c cable with the laptop. The laptop can dictate how much power it wants to draw etc on demand and the charger will change voltage etc to accomodate this. Now cellphones also supports this to a degree for quickcharge etc.

Anyways, there are things like USB PD (power delivery) protocols and QC (quick charge) protocols etc. It is possible the laptop charger is limited to only work when the communication for the laptop is opened up.

The fan’s problem is, it is possibly something very basic, doesn’t do communication, and so the charger turns off for safety reasons. Eg. to not blow up the fan in case it can’t handle the power the charger will put.

Technically, the charger is suppose to fall back to usb-a levels of power delivery, but I guess that specific charger does not.

Anyways, lots of reading you CAN do on the subject, but that is the summary.

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3

Yes. Silly me. The power brick supports but is not limited to Quickcharge 3.0. And obviously (now you’ve pointed it out) there has to negotiation between the charger and the object to be charged as to which charging protocol to use.

My phone has some sort of circuitry in it to manage charging and to allow various fast charge protocols. The fan, as far as I can see, has two no-name brand cells, slightly bigger than a flash light cell.

The power brick and the laptop charger obviously have different default modes. The power brick charges the fan, but not in any quick mode.

Thank you for your reply.

4

When I saw one of these for the first time (with the cable that was thicker than the USB C plug) I reckoned to myself I’ll avoid this lot for as long as I can.
Can’t say I’ve changed my mind either since then…

5

USB C standards or rather specs is a real minefield, almost like HDMI specs.

If you buy a USB C cable or charger, you have to read very carefully what you are buying and exactly what it supports.

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6

Correct me if I’m wrong but USB C doesn’t appear to taking over??

7

Indeed. If nothing is talking back, it should just remain at 5V max 2A or something like that. Like a dumb charger. At least, that is what I thought it does.

My wife forgot her USB-C style laptop charger at home one day. We were about 80km away when we realised this. We had to make a quick decision: Drive back to get it, try to buy one from a shop, or make do with what we have. Since it was Friday afternoon, Worcestor was the closest town (in the wrong direction) likely to have it, and trying a few phone calls were unsuccessful, I took the power bank from my bag and plugged it into the laptop, fully expecting it to not work. I was surprised to see the laptop accept the power and actually charge! Not very fast, not such that you can run it for hours on end, but enough that we could go with option 3: Make do.

The laptop is an Asus Zen-book. Pretty impressive little things.

8

Some of these cheap devices only connect the power pins. With USB-C you have to pull down one of the CC lines before you get 5V. My guess here is that the laptop charger actually implements the spec correctly, but the fan does not.

Some cheap chargers actually are just USB-A devices (some with a USB-C socket), so they just output 5V always, some support QC2, which can also output other voltages but with a much more primitive protocol.

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9

See 3rd pic
So this unit will auto select the correct voltage for your gizmo??

10

Yup. Unit powers up at 5V, 500mA, then communicates the preferred power requirements. If the charger can meet those requirements, then it ramps up to that setting.

I have a selection of boards like this:

image
image460×375 46 KB

To use USB charger as a general power supply.

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11

At the last electronics show in China, I saw vendors selling Type-C cables capable of 240W power delivery and 40Gbps data transfer—48V at 5A.

One can only imagine what could be powered with that!

But one thing is certain: USB Type-C is working well across many devices. The current challenge with Type-C is that it can both send and receive power. not really a challenge, but more a “keep in mind”

For example, let’s say you’re charging your laptop from a Type-C power brick. There’s a chance that instead of charging the laptop, the laptop might start charging a power bank instead! It’s almost like a tug-of-war over who gets the charge.

This happens because both devices communicate their power needs, and whichever one gets the “right to charge” first will receive power. You will have to pull out the cable and try again!

Regardless, Type-C is amazing!

I also saw a Type-C to 12V cable at Outdoor Warehouse, designed to power small 12V lights from PD power banks—a very clever idea!

Remember, not all Type-C ports support charging with a Type-C to Type-C cable. To avoid this issue, use a A-C cable. AS @tinuva mention. Its all about communication.

But then you also get Type-C that that will only give the right amount of power if you use the correct charger, with the correct cable with the correct phone.

The EU told the world that Type-C is the way forward and that Type-A is not so welcome anymore… BUT… they it never talked about charging protocols!

Mens kan nie voorbly nie!!!

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12

I think that was really about getting Apple to abandon their proprietary socket.

13

That was a major reason, yes, but also to establish a universal charging standard.

Think about it—how many devices need charging, like laptops, cellphones, and others? When you buy a new device, it usually comes with a charger in the box (though I know this has changed recently). But looking back a few years, it was the norm.

Having a charging standard means everyone can use the same charger, reducing electronic waste.

Remember when you traveled a few years ago? You needed a separate charger or cable for your earphones, maybe a micro USB or a proprietary cable. Then there was the phone charger—either micro, USB-C, or Lightning. And don’t forget the bulky laptop charger, often with a connector or voltage that only worked with that particular unit (and if you forgot it at home, you’d have to buy a new one).

You also needed a travel adapter for your three-prong plug.

I remember the first time I traveled abroad—you literally needed a case for all your electronics, and everything had to be packed just right, because heaven forbid you needed to charge your laptop at an airport!

Now, with a common standard, you only need one charger and maybe two USB-C cables—one for your laptop and the other for everything else, like your phone, earphones, or power bank.

And with the new USB-C that supports up to 100W, along with new laptops supporting Type-C charging, I really believe you can travel so much lighter. It’s also better for the e-waste problem.

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14

There is no chance of that happening.

15

In a way, that standard already existed. Using USB for charging/power goes back to the first version of the standard. A charger could also indicate that it is a dedicated charger (or a dedicated charging port on a laptop would to this) by shorting the data lines together. When USB-C came on the scene, naturally you’d want to be backwards compatible while also adding higher power levels.

So I think this was more a case of not regressing towards not having a universal charging standard, when we already had a pretty good one, if less capable :slight_smile:

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16

Oh yes, I’ve seen that happen many times before (especially in my line of work)!

If both the laptop and the power bank have PD capabilities and support bidirectional charging, this can occur.

So, when you’re using a power bank to charge a laptop, a quick fix is to disconnect and reconnect the cable. Keep in mind, this issue only arises when a power bank is used to charge a laptop.

To address this, some manufacturers include a dedicated Type-C output port on their power banks specifically for laptop charging.

17

https://archive.ph/Ve4jI

18

The initial USB standards was developed by Intel. They were needing a universal interface to connect to PC peripherals.
Then it appears to have been controlled by a dedicated USB body since it became so big.

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19

The EU has become the last honorable standards custodian.
This is built into the way they operate so they can’t ditch it.
They are not the biggest market but are big enough to have to be factored in so effectively they determine the world’s standards.

20

Yes. Our own standards for appliance efficiency are based on EU standards. And EU test results.

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