When using a power bank with adjustable current I'm just wondering how the current is adjusted? it can't be anything to do with resistance of the recieving component because this would be constant, using ohm's law is this done by increasing or decreasing the voltage from the power bank?

  • \$\begingroup\$ adjusting current means simply changing voltage. There is no way to keep the output power constant while a load is dynamic. \$\endgroup\$
    – emre iris
    Commented Aug 7, 2020 at 13:52
  • \$\begingroup\$ @TMax: Show me a power bank with adjustable current, then we can talk. Power banks usually have a fixed output voltage, and a maximum current limit. They don't normally have an adjustable current. \$\endgroup\$
    – JRE
    Commented Aug 7, 2020 at 14:02
  • \$\begingroup\$ I'd have to get a photo next time I'm at that particular site I can't remember the make of it but it's and old school one by the looks of it \$\endgroup\$
    – TMax
    Commented Aug 7, 2020 at 14:07
  • \$\begingroup\$ what is an "old school powerbank"? Are you sure you're using the right word there? \$\endgroup\$ Commented Aug 7, 2020 at 14:39

1 Answer 1


When you're regulating based on current you are actually converting that current to a voltage. This is done either through a shunt, a current transformer, or some hall effect sensor. You then end up regulating THAT voltage in the same way you would regulate your output voltage.

It really goes deeper than that depending on how you're regulating, but for voltage mode control that about sums it up.

EDIT: I should mention that I'm talking about SMPS, there are other ways of creating adjustable current sources that don't work like this.


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