Voltage Drop Calculator (DC Circuits)

Battery animation
Battery or system voltage.
Current flow in the circuit.
One-way distance. Calculator will use round-trip automatically.
Copper has lower resistance. Aluminum requires thicker wires.

This DC Voltage Drop Calculator estimates voltage loss across long wire runs in low-voltage battery systems. Enter voltage, current, wire length and conductor type to know how much voltage is lost end-to-end.

Why Voltage Drop Matters

DC systems are sensitive to voltage loss because the supply voltage is already low. Excessive drop causes devices to underperform, shuts down controllers, increases heat and wastes power.

What Affects Voltage Drop

  • Wire length
  • Current (A)
  • Copper vs Aluminum conductivity
  • Low system voltage (12-48V more sensitive)

Where This Calculator Is Useful

  • Solar systems
  • Battery banks
  • eBike wiring
  • Low-voltage DC projects
  • Off-grid systems

Frequently Asked Questions

Q: What is acceptable voltage drop?
Many DC systems target a maximum of 2–3% drop for reliable performance.
Q: Is copper better than aluminum?
Yes, copper has lower resistance and provides lower voltage drop for the same current and distance.
Q: Does cable length matter more or current?
Both contribute equally — long cable and high current dramatically increase voltage loss.
Q: Does low system voltage increase drop?
Yes. 12V and 24V systems are more sensitive to voltage loss than 48V or higher systems.
Q: Is this calculator only for DC circuits?
Yes, this version is optimized for DC wiring. AC versions use different impedance calculations.