If I have a device that requires 5V and 2A to function, what kind of power supply would I need to power 4 of these devices at the same time to their full capacity?

Here is an example setup: enter image description here Power bank-Portable Charger 30000mAh 2USB Ports (Output 5.0V 2.0A)

enter image description here USB Hub-4-Port USB 3.0 Hub

enter image description here Device-Electric Cloth Heater Pad Heating Elemen

===================================================================== Based on this battery, im pretty sure the portable battery must be able to at-least give off a total of 8 amps.. enter image description here ZeroLemon ToughJuice 30000mAh 7A Output Portable Charger t

But im willing to bet it needs more than that to maintain that sort of power for over two hours. I wonder if a USB hub can handle 4 amps in a single cable...


1 Answer 1


You will be connecting all devices in parallel, so the voltage requirement stays constant at 5V. To get the needed current just sum up all device input currents. If you have 4 devices with 2A each you need 8A. The power is V*I, in this case 40W.

If you want to power the devices from battery for a longer time, you obviously also have to keep in mind the capacity of the battery. 8A for 2h requires the battery to have at least 8A*2h = 16Ah = 16,000 mAh.
When choosing the equipment for this make sure all devices can handle the current you need. Check this question for more detail on power handling of USB devices.

Is this answering you question completely? Otherwise feel free to specify more precisley what you want to know.

  • \$\begingroup\$ Im pretty sure the first portable power-bank example I provided would not work for this scenario because it only says it outputs 2amps. Im thinking two of these will do the trick instead amazon.com/Portable-30000mAh-Flashlight-BONAI-Compatible/dp/… . Giving me 3.5 hours of heat for just under $80 \$\endgroup\$
    – eromod
    Jan 13, 2020 at 9:17
  • \$\begingroup\$ The first on also says 2A / USB-Port and offers two ports, giving you the 4A you want. \$\endgroup\$
    – jusaca
    Jan 13, 2020 at 9:24
  • \$\begingroup\$ Yea, but its unbranded and the wording it uses is "This" power bank output, instead of "each usb outputs". Im much more comfortable of risking the wording in the third battery I provided out of them all. \$\endgroup\$
    – eromod
    Jan 13, 2020 at 9:28
  • 1
    \$\begingroup\$ I agree, I would always use a branded one with specifications one can (hopefully) trust. \$\endgroup\$
    – jusaca
    Jan 13, 2020 at 9:30

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