"Intelligent" variable voltage USB chargers powering Arduino projects.

I have a number of Arduino projects which I power by 5volt single-way USB chargers and a powered USB hub. These work OK but I am now wanting to replace the powered USB hub with a multi-way USB charger. Now, I have come across "intelligent" chargers such as this:

https://www.banggood.com/OLAF-3_1A-Multiport-QC3_0-Intelligent-Fast-Charging-EU-US-UK-Plug-Travel-USB-Charger-For-iPhone-X-XS-Xiaomi-Mi8-Mi9-S10-S10-p-1554355.html

Which appear to be able to ramp up the voltage on demand on demand (depending perhaps on which socket you use on the charger) an now I am uncertain if this poses a risk for the 5 volt Arduino. I guess by default, the charger provides a maximum of 5 volts, however, it can test the appliance being charged to see if it requests a higher voltage. My concern is that a simple failure may cause an overvoltage. Has anyone experience of these ?

It appears, incidentally, difficult to find multi-way chargers which don't support this higher voltage feature.

My understanding is that intelligent chargers perform negotiation via the USB data signals with the attached device to get charging parameters. An Arduino won't be capable of doing this so the charger will default to standard USB voltage of +5V.

From a practical point of view it would be remarkably stupid if an industry standard like USB were approved that enabled blowing up legacy devices in seemingly normal operation.

Less than $40 for a 3.1A charger, so cheap! That's just too cheap, can't be good/safe. Not so long ago I opened up a failing single port adapter, and was quite impressed with the complexity of the PCB that was in it (dozens of components squeezed on both sides). And oh, the irony... It's shipping from a China warehouse, and "can not ship to your location". I thought Hong Kong is supposed to be an inalienable and inseparable part of China, that's at least what the politicians tell us all the time...

OK. I see a price of $4.99 ($=USD). I Don't know about Hong Kong, but if it is not orderable from there, then the retailer would have every reason to show an exaggerated price for the item.

I agree that any standard governing these fast mode USB charging products would respect legacy (5Volt only) devices. However, low cost manufacturers are prone to cost cutting measures and safety considerations implied by such standards (fuses, overvoltage protection, isolation between primary and secondary transformer windings etc. etc.) may be ignored. But, if there is no known history of these devices destroying equipment by incorrect activation of the enhanced power modes, I may chance it.

That’s pretty much the same value. I get to see my own dollars, that’s why I said <$40 is very cheap, as it is very cheap, indeed about 5 USD.

The part that I opened up did not have a transformer to begin with - it was about the size of a regular UK style plug, but where the cable normally comes out it had a USB socket. No fuse, either. The product linked to above probably also doesn’t have a transformer. Helps keeping it cheap, and you don’t need a transformer to convert 220V AC into 5V DC.

6v6gt: I agree that any standard governing these fast mode USB charging products would respect legacy (5Volt only) devices. However, low cost manufacturers are prone to cost cutting measures and safety considerations implied by such standards (fuses, overvoltage protection, isolation between primary and secondary transformer windings etc. etc.) may be ignored. But, if there is no known history of these devices destroying equipment by incorrect activation of the enhanced power modes, I may chance it.

Of course there's the (hopefully remote) possibility it destroys equipment, electrocutes you, and/or burns down the house because it's a cheaply made piece of garbage, but that's different than blowing stuff up specifically because it's an Intelligent USB device.

wvmarle: The part that I opened up did not have a transformer to begin with - it was about the size of a regular UK style plug, but where the cable normally comes out it had a USB socket. No fuse, either. The product linked to above probably also doesn't have a transformer. Helps keeping it cheap, and you don't need a transformer to convert 220V AC into 5V DC.

Well, that's not strictly true.

Of course it has a transformer, but a tiny little one. And it likely has a fuse also, in SMD format.

I found that rather odd as well. Of course you can get transformerless power supplies, normally low current and built into devices (say a time switch) where the lack of isolation with the mains power supply is not an issue. But not on a device with exposed contacts and not with 15 watts output.

I don't have the board any more so can't show you photos. Must have been such a small transformer I didn't recognise it as such.