Electronic – Why is the circuit’s current far lower than expected with 2.6v / 220Ohm / and LED

current measurementledohms-law

I have a very simple circuit which I have measured the current to be only 3mA but should be in the range of 18mA.
I have a simple circuit using 2 AA batteries (NiMH) at 1.3V each in series for a total of 2.6V and a 220Ohm resistor along with my basic red LED.

schematic

simulate this circuit – Schematic created using CircuitLab

I = E/R

Using Ohm's law I calculate that I should get approx. 11mA of current
.011 = 2.6 / 220

Double-Checked Resistor Value

I double-checked my resistor with meter and they are at 215 Ohms but that would mean I would get slightly more current anyways.

Double-Checked Voltages

I also measured total voltage in circuit and it does measure at 2.6V.
I measured the voltage drop across the LED and it was at approx 1.775 which seems correct also.

Why might I be getting less current than expected (3mA versus 11mA)? Is there something I'm not calculating properly for?

Best Answer

The diode has a forward volt drop of 1.775 volt hence the current that this circuit drives might be only (2.6 - 1.775)/220 = 3.75 mA.

You don't have the full 2.6 volts across the resistor hence 2.6/220 is meaningless.

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