Two Voltage Source Current Calculation
Why this calculation matters
Many practical circuits use more than one voltage source. A backup battery may sit beside a supply. A charger may oppose a cell. Solar strings may help or fight each other when polarity is wrong. Current depends on the net voltage and the total resistance in the closed loop.
This calculator uses a loop method. It treats each source as a signed voltage. Aiding sources add together. Opposing sources subtract from each other. Custom polarity lets you choose the sign for each source. The tool then divides the net voltage by total loop resistance.
What the results mean
A positive current means the assumed loop direction is correct. A negative current means the real current flows opposite to that direction. This is useful because the magnitude still shows the actual current size. The sign only explains direction.
Resistance entries should include every part of the path. Add load resistance, internal source resistance, wire resistance, and any extra series resistance. Small internal values can matter when currents are high. Long leads can also create measurable voltage drop.
The load voltage drop is found by multiplying current by load resistance. Load power is current squared times load resistance. The total resistive power shows heat produced by all series resistance. Source power values show whether each source delivers energy or absorbs energy.
Good electrical habits
Always check polarity before connecting two sources. Two batteries in series can create a high useful voltage. The same batteries in opposition may cause charging current, heating, or damage. Never rely only on labels. Test terminals when safety matters.
Use conservative resistance values when estimating fault current. Use measured values when checking a real bench circuit. Temperature can change conductor resistance. The optional temperature adjustment helps estimate that effect for leads.
This calculator is best for direct current series loops. It also works for simple equivalent circuits. It does not replace full network analysis for complex branches. For multi node circuits, reduce the network first or use Kirchhoff equations.
Common uses
Compare bench supplies, battery packs, charger paths, and sensor loops. Try safe values first. Then refine resistance, polarity, and temperature after measurements are available for the exact circuit.