1. What is Internal Resistance?

Internal resistance (r) is the opposition to the flow of current within a power source itself. It causes voltage drop when current flows and is measured in ohms (Ω).

2. How Does the Calculator Work?

The calculator uses the internal resistance formula:

Where:

• \( r \) — Internal resistance (Ω)
• \( \Delta V \) — Voltage drop (V)
• \( I \) — Current (A)

Explanation: The internal resistance is calculated by dividing the voltage drop by the current flowing through the circuit.

3. Importance of Internal Resistance

Details: Internal resistance affects battery performance, power efficiency, and voltage regulation. Lower internal resistance generally means better performance.

4. Using the Calculator

Tips: Enter voltage drop in volts (V) and current in amperes (A). Both values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What causes internal resistance in batteries?
A: It's caused by resistance in electrodes, electrolyte, and other components. It increases with battery age and temperature changes.

Q2: How does internal resistance affect battery life?
A: Higher internal resistance reduces available voltage under load and decreases usable capacity, effectively shortening battery life.

Q3: What's a typical internal resistance for AA batteries?
A: New alkaline AA batteries typically have 0.15-0.3Ω, while NiMH rechargeables are around 0.02-0.1Ω.

Q4: How can I measure internal resistance?
A: Measure open-circuit voltage, then voltage under load. The difference divided by current gives internal resistance.

Q5: Does internal resistance change with state of charge?
A: Yes, it typically increases as the battery discharges, especially in the last 20% of capacity.