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Can you wire USB Ports in series? Answered

Hi, All.

New to the forums, but have used several instructables and love this site. I'm currently trying to make a notebook cooling fan using a 12 Volt fan pulled from an older computer. Obviously I can wire it to the USB ports, but the 5V I'm getting there aren't enough. Would it be possible to wire 2 usb connections in a series, giving me 10V at 500mA, or am I just asking to fry my ports? I've seen some external hard drives that use 2 USB ports for power, so I'm assuming it can be done, but I didn't know if you needed anything other than a series connection.



Low voltage fans are available relatively cheaply that will work on 5v from a usb. It is not too tricky to take a 12V ish tap off the battery if you feel confident enough.

Someday I'll hit that level of confidence, but probably not now under warranty! Thanks for the all the info though, guys.

Think about it, if you did that, you'd be connecting 5+ to the computer's ground. As ground is shared between all the USB ports and so is 5+. So it would be pretty much the same as connecting the 5+ to ground.

I am fairly sure you'll fry your ports. I have one of those "two port" drives. It uses one port for power, and the other for signal (in my case, the drive enclosure has two USBs and a firewire connector -- you can connect for I/O through either USB or FW, but you have to use the other USB for power).

Hmm. So much for an awesome 12V fan arrangement running. Thanks!