this post was submitted on 24 Aug 2024
87 points (93.9% liked)

No Stupid Questions

35780 readers
989 users here now

No such thing. Ask away!

!nostupidquestions is a community dedicated to being helpful and answering each others' questions on various topics.

The rules for posting and commenting, besides the rules defined here for lemmy.world, are as follows:

Rules (interactive)


Rule 1- All posts must be legitimate questions. All post titles must include a question.

All posts must be legitimate questions, and all post titles must include a question. Questions that are joke or trolling questions, memes, song lyrics as title, etc. are not allowed here. See Rule 6 for all exceptions.



Rule 2- Your question subject cannot be illegal or NSFW material.

Your question subject cannot be illegal or NSFW material. You will be warned first, banned second.



Rule 3- Do not seek mental, medical and professional help here.

Do not seek mental, medical and professional help here. Breaking this rule will not get you or your post removed, but it will put you at risk, and possibly in danger.



Rule 4- No self promotion or upvote-farming of any kind.

That's it.



Rule 5- No baiting or sealioning or promoting an agenda.

Questions which, instead of being of an innocuous nature, are specifically intended (based on reports and in the opinion of our crack moderation team) to bait users into ideological wars on charged political topics will be removed and the authors warned - or banned - depending on severity.



Rule 6- Regarding META posts and joke questions.

Provided it is about the community itself, you may post non-question posts using the [META] tag on your post title.

On fridays, you are allowed to post meme and troll questions, on the condition that it's in text format only, and conforms with our other rules. These posts MUST include the [NSQ Friday] tag in their title.

If you post a serious question on friday and are looking only for legitimate answers, then please include the [Serious] tag on your post. Irrelevant replies will then be removed by moderators.



Rule 7- You can't intentionally annoy, mock, or harass other members.

If you intentionally annoy, mock, harass, or discriminate against any individual member, you will be removed.

Likewise, if you are a member, sympathiser or a resemblant of a movement that is known to largely hate, mock, discriminate against, and/or want to take lives of a group of people, and you were provably vocal about your hate, then you will be banned on sight.



Rule 8- All comments should try to stay relevant to their parent content.



Rule 9- Reposts from other platforms are not allowed.

Let everyone have their own content.



Rule 10- Majority of bots aren't allowed to participate here.



Credits

Our breathtaking icon was bestowed upon us by @Cevilia!

The greatest banner of all time: by @TheOneWithTheHair!

founded 1 year ago
MODERATORS
 

Basically I'm trying to de-clutter the cables to my charging station, and was hoping to use a 3-way cable for my phone, watch, and headphones.

My main concern is if one device is able to successfully negotiate QuickCharge or PD, would that send 9-20 volts to the other devices?

e.g. if I grabbed the wrong cord and hooked it into my laptop, the laptop requests 20v, would that PD negotiation succeed and also send 20v to my 5v devices on the other two leads?

I've only used these kinds of cables with USB-A and chargers that can only output 5V. Most of my chargers now are QC/PD so I'm curious if I should avoid those or take any particular precautions.

you are viewing a single comment's thread
view the rest of the comments
[–] NeoNachtwaechter@lemmy.world 25 points 2 months ago* (last edited 2 months ago) (1 children)

My main concern is if one device is able to successfully negotiate QuickCharge or PD, would that send 9-20 volts to the other devices?

Yes.

QC negotiation works by changing the voltage. This communication would be broken if you plug several devices to 1 charging port.

So you better get a charger with several ports where each port is capable of delivering QC / PD. They have independent communication then, and each device gets it's proper voltage.

[–] AVincentInSpace@pawb.social 15 points 2 months ago (2 children)

That's assuming this cable forwards PD signals at all.

[–] PM_Your_Nudes_Please@lemmy.world 3 points 2 months ago* (last edited 2 months ago)

That would actually be the safer scenario, as a failure in the PD handshake simply defaults to 5v which every USB device can accept. It would be more dangerous to only have the PD negotiation be on one of the three ports, because then you could potentially burn out devices on the other two by sending them too much voltage.

I guess the best case scenario would be to have the PD signal run on all three, then default to low voltage if any of them fail. But that's likely not what they're doing, because then things would only fast charge if all three ports are plugged into fast charge devices. Because an unplugged tail would likely register as a failed PD handshake.

[–] NeoNachtwaechter@lemmy.world -1 points 2 months ago* (last edited 2 months ago) (1 children)

No. In QC it is the main voltage that is changed. No extra signal lines.

[–] AVincentInSpace@pawb.social 7 points 2 months ago

USB-PD changes thr main voltage in response to a handshake protocol on the C1 and C2 data lines, which this cable likely doesn't connect for precisely this reason. Qualcomm QC still uses D+ and D- to negotiate the higher voltage, which this cable likely wouldn't connect either.