# Can I split a USB cable's male end, add a second male plug, and draw 10V from 2 ports instead of 5V from one port for a single device?

Say I have a device that accepts 10V @ 2A, and I have a wall-wart with two USB plugs that both output 5V @ 2A. Can I add a second male connector, connect both connectors to the wall-wart's two ports, and draw a cumulative 10V @ 2A?

This question's answer indicates that this would cause havoc for motherboards or other electronic devices, but there's a lot more going on with a motherboard than with a power block. Does this answer still apply?

• No, the grounds will be shared and you'll short your system out. – Majenko Oct 31 '14 at 22:06

## 1 Answer

No you cannot! Both USB sockets are probably even the same power supply so the 5V of both USB ports is connected to eachother and the 0V/GND is also shared.

If you had two different adapters with internal galvanic isolation (transformer) it would be possible to make 10V 1A of two 5V 1A USB ports.

• Or 5V 2A without isolation. – Ignacio Vazquez-Abrams Nov 1 '14 at 0:01
• My original question had a typo, the power outputs on the wall plug are 5V @ 2A, not 1A, but that doesn't change the answer in the original context. Thanks! – Bryson Nov 5 '14 at 19:14
• Would a "power supply" that takes in both USB inputs (5V 2A) and outputs 12V at an amperage greater than 1A be difficult/impossible/complex to build? Or is it something I could do as a learning project? – Bryson Nov 6 '14 at 19:21
• If I unstand you well, you want to make a device that converts 5V into 12V. This is normally done using a boost converter. However you need at least the same input power as output power. Output power is at least 12W (12V * 1A), and input is 10W (5V * 2A). So this is already impossible. When you have 5V * 4A it would be possible given an efficiency of 60% which is possible to make. To make a boost converter look for example at the LMR61428. If you don't have much experience with electronics I would however advice against building a boost converter because it is not very straightforward. – Douwe66 Nov 8 '14 at 9:35