Dual USB Cigarette lighter adapter problem

[jbs]

Hi,

I have bought this dual USB adapter and I want to connect a Gopro Hero 11 on USB type A and a 12V micro fan on USB type C.

https://www.amazon.co.uk/UGREEN-Charger-Charge-Adapter-Compatible/dp/B09DSV9G78

I have connected the fan to a 12V USB C PD trigger modul, to force it to pull 12V.

My results:

-) When I only plug in the fan, the voltage reads 9,14 V

-) When I plug in both, the Gopro and the fan, the voltage reads 5,14 V on the fan.


Do I have the wrong adapter? I basically want the fan to run with at least 9 V...how can I achieve that?

Thanks in advance,
Joël

[sparkydog]

Have you checked what simultaneous outputs are supported? A.co.uk hates me, so I'm not sure what exact charger you're using, but if it's a 30W, well...

As you may already know, USB PD doesn't have a 12V out; your options are 5V, 9V, 15V, ... So your "12V USB C PD trigger module" is most likely only requesting 9V, and your voltage reading with only the fan plugged in is expected. Also, 9V only delivers up to 27W, which is basically the limit of a 30W charger. The moment you plug something else in, it's probably limiting both ports to 5V/15W, which would explain why the fan drops to 5V.

I suspect you need a charger that can deliver 15W on USB-A and at least 27W on USB-C simultaneously. For example, https://www.ugreen.com/products/ugreen-69w-usb-c-car-charger.

"But I don't need 27W for the fan!" I hear you complaining. True, but I'm not sure USB PD works that way; I'm not sure you can negotiate for low wattage at high voltage. (Mind, I'm fairly confident nothing will go wrong if you draw less wattage, but the charger has to assume that, if you're asking for 9V, you might draw no less than 15W, and so won't give you the requested voltage if it can't guarantee at least 15W and possibly 27W.)

Your other option is to either use a 5V fan, or use a DC-DC converter to run the fan off 5V. If you just need "a fan", Noctua makes fans from 40mm to 200mm in 5V.

[jbs]

Thanks for your help with the USB adapter issue! 🤗 Upgraded as you suggested, and everything's working great now. Really appreciate it. You saved my project 👍

[sparkydog]

Cool; glad that worked! Thanks for sharing the update!