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I have a USB-C PD & QC3.0 device. It takes 20V @ 2.25A (45W), or 15V@3A to charge.

I also have a 15V 5A portable charger with a female 5.5mm x 2.5mm output port. I plan to connect the 5.5mm x 2.5mm female output port to the USB-C device via a 5.5mm x 2.5mm-to-USB-C-adapter.

adapter

I do not need the fast charge modes. I just want to know : will it charge my device? Will it break my device?

p/s (My portable charger also has other output modes - 12V, 9V, 19V & 5V, I've only used the 5V all this time, curious to try other modes)

Azrudi
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  • Impossible to answer without knowing all the details of the device you want to charge. Some devices (from Apple, Dell etc.) simply refuse to charge when the power adapter is not recognized. It might indeed break your device also. Do you really want to take the risk of breaking your device ? Also off-topic: "Questions on the use of electronic devices are off-topic" – Bimpelrekkie Aug 21 '17 at 14:15
  • This cable looks to be intended the other way: getting 5V out of USB C and put it into the barrel connector. – user3528438 Aug 21 '17 at 15:05
  • I suspect 19V out mode is most efficient and 5V in is least efficient method to charge device, but it "may" work – Tony Stewart EE75 Aug 21 '17 at 15:18
  • If you don't want fast charging mode (higher voltage/higher current), why do you want to try 15V? – Ale..chenski Aug 21 '17 at 18:27
  • @AliChen the laptop is rated 45W, and its native charger has a mode 15V@3W. I am wondering if I could use this alternative portable charger (hack it into a battery pack) at the same voltage & current rating - also it could charge 19V @ 3A as well. – Azrudi Aug 22 '17 at 00:17

1 Answers1

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The question is essentially this: If I boldly apply a plain 15V/5A source to a device designed to QuickCharge 3.0 proprietary specifications, will my device charge?

The answer is: likely not. The QC process starts with the default 5V level, and then device request higher profiles by manipulating with D+/D- wires and setting certain DC levels. This is a sequential process, and if the initial handshake fails, the device will likely not engage higher charging rates and consume more power from charger.

The second question is, will the bold 15V5A fry my QC3.0 input circuitry? The answer is "who knows", unless the device datasheet explicitly says that it is tolerant to any voltage up to 20V regardless of QC presence, or the schematics of the charger section inside your device is known, with all related datasheets.

You have made the right choice to use 5V only, please continue to run it in this mode for your safety and safety of your device. However, in all likelihood, your device will take only 500 mA and charge very slowly, if at all.

Ale..chenski
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  • Thanks. I do not see any mention of QC presence, I think the laptop manufacturer simply assumes that users will use the supplied charger. But the original supplied charger does have 5V, 15V and 20V modes (2A, 3A and 2.25A respectively) labelled on the plug. I can't select those modes manually on the charger I suppose QC 3.0 takes care of that. My portable bank does have 5V, 12V, 15V and 19V modes up to 3A. I ask the experts here who understand more about the PD/QC3.0 standard - I would rather not experiment (yet) – Azrudi Aug 22 '17 at 00:20
  • @Azrudi, you said you have "USB-C PD and **QC3.0**" device. The power profile selection could be over PD, or over QC 3.0, we don't know. It looks clear however that your other charger, having just two-wire jack, can't provide any intelligence to Type-C end of cable. Therefore the laptop wouldn't know how to deal with that input. There is not much information if you just say "a device", "a charger". So you got "an answer". – Ale..chenski Aug 22 '17 at 01:01
  • Thanks for your replies. I am looking for a hard yes or no answer really, when the words "probably" used it implies we don't know for sure & the answer could be wrong at a later date. Your paraphrasing of my question is essentially correct. When I said device, I meant laptop. I used the term device because I also would like to know the generic answer too to other new PD + QC3.0 compliant devices like tablets, phones, wireless cameras, hand drill trickle chargers. To simplify, my specific case: 1) laptop that complies to QC3.0 2) charger that complies to QC3.0 3) plain 15V/5A source – Azrudi Aug 22 '17 at 10:27
  • @Azrudi, The QC protocol is not public, only indirect descriptions of functionality from some ICs (that support QC) give some hints. And details of "compliance to QC3.0" are unknown (if this thing ever exists), so no one knows how your particular "device" will react when subjected to straight out-of spec high voltage. And yes, the answer to questions like "will my interface withstand shorts to 5 or 15 V" is a moving target, because specifications do evolve, and test requirements change over time. – Ale..chenski Aug 22 '17 at 15:51
  • Fair enough, thank you very much. Although I am not sure what you mean by out-of-spec voltage, because the 15V and 5V are also what the charger that came with the device provides. The portable charger I'm trying to make could also output 9V, 12V etc but I am wondering if its worth pursuing 15V@3A. – Azrudi Aug 22 '17 at 23:21
  • @Azrudi, I believe it was already explained, that QC negotiation protocol starts with 5V, so starting from 15V would be out of protocol specifications. – Ale..chenski Aug 23 '17 at 00:20