When connecting multiple loads to a single battery, how can one calculate the total current output of the battery? Is it possible to simply add the current across all loads, or is the current of the battery equivalent to the current of only one load? Please take the example below as a simple way to visualize the scenario so that it may be answered in a simple and effective manner.


Say I have a battery and three LED lamps connected to it. If, for instance, each lamp is rated at 100 milliAmps, what is the total current output of the battery at a given point in time?

Is it:

A) 100 mA


B) 300 mA

If it depends on parallel or series, please explain what would happen in either situation.


closed as off-topic by Martin, JamalS, Rob Jeffries, Neuneck, ACuriousMind Dec 8 '14 at 14:03

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  • $\begingroup$ I believe I have remediated this by including a more general question above. Please let me know if this is satisfactory so that the question can be unlocked and for my future reference. Thank you. $\endgroup$ – salamander Dec 9 '14 at 5:58
  • $\begingroup$ Furthermore, if you vote down, please give a reason. This will make things more productive. $\endgroup$ – salamander Dec 9 '14 at 6:00
  • $\begingroup$ A good resource which also answers my question: physicsclassroom.com/class/circuits/Lesson-4/Parallel-Circuits $\endgroup$ – salamander Dec 11 '14 at 8:14

Each LED has both a voltage rating and a current rating (100mA).

When connected in parallel, they will all receive the voltage of your power supply and draw 100mA each, so the total will be 300mA.

When connected in series, they will split the supply voltage between them, so the supply voltage will have to be 3 times the individual LED voltage rating. Each LED will have its rated current of 100mA passing through it (since they are all in series), so the total power consumed is still the same as in the parallel case.


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