Resistors in battery-powered LED device and Arduino
A better way of doing this would be to test it yourself. Measure the off-load voltage of your battery pack, then connect a resistor with a known value (can measure it first) and then measure the on-load voltage.

Using Ohm's law, you should be able to find if there is any built in resistor in the battery pack, and an approximate value. If you find that the value is very low (probably less that 1 Ohm), chances are it will just be the batteries internal resistance and the battery pack does not have a built in resistor.

I would never say it is safe to assume anything, always better to test first!







simulate this circuit &ndash; Schematic created using CircuitLab