USB Meter - For Measuring Capacity of a USB Power Bank & Other 5V Devices


You have bought a power bank and are wondering if it really measures up to the advertised Capacity?

Check with this Power Meter.
USB Meter

  • You can connect it to any USB Power Source like your Power Bank.
  • It will Show you the Output Voltage of the Power Bank - This should be 5V
  • On the USB Female side you connect your Load.
  • You can then see the Current that the Device Consumes.
  • Leave it on for a while and it can give you an indication of the Power Consumed.  This is also the Power delivered by the source (Could be your Power Bank)

It measures Voltage & Current - Power = Voltage x Current (For DC Voltages like this one)
The Total Energy that can be delivered by your Power Bank = The Capacity of your Power Bank.
Energy (Or Capacity) is the ability for the Power Bank to give X Watts for T Time before it runs out of juice.
Hence TIME is the factor that comes into play to measure the Total Energy that can be delivered by your Power Bank or The Capacity of your Power Bank

Capacity = Total Energy that your Power Bank can deliver = Watts x Time = V x I x Time

Since a Power Bank is usually 5V it is sometimes mentioned as AH - = I x Time (Assuming Voltage is fixed at 5V)

To measure the capacity you can do the following;

  1. Charge your Power Bank till it is full  - Indicated by the LED or display on your Power Bank.
  2. Disconnect it from the charging source
  3. Connect the USB Meter to the Power Bank - Ensure that the AH display reads 0 - else press the button for a few seconds to reset the reading to Zero).
  4. On the output side connect a simple USB LED which draws (These usually consume between 0.5 to 1W - the exact value does not matter)
  5. You can see the current drawn by the device (LED).
  6. Leave it on until the Power Bank exhausts its energy/capacity.
  7. Check the AH directly on the display. - After reading you can reset it back to zero for the next reading - Some Meters can store multiple readings and cycle through them numbered as 1,2...
For Video details check this youtube video







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