Read volts as the electrical difference a battery provides between its terminals. Compare open-circuit, nominal, fully charged, and cutoff voltages so labels like 3.7 V, 4.2 V, and 12 V stop feeling interchangeable.

Track current as the rate electric charge moves through a circuit, using amps, milliamps, coulombs, amp-hours, and milliamp-hours. Calculate how much charge leaves a battery when a device draws a steady current for a known time.

Use Ohm’s law, V = I × R, to predict how much current a load will draw from a battery. Reason through high resistance, low resistance, short circuits, internal resistance, voltage sag, and why large currents can become dangerous.

Apply the previous explanations in a guided problem.

Calculate electrical power with P = V × I and connect watts to how hard a battery is working right now. Compare small electronics, heaters, motors, and chargers by their power draw instead of only by their voltage or current.

Estimate stored or delivered energy using watt-hours and joules, including Wh = V × Ah and runtime = Wh ÷ W. Spot why mAh alone can mislead when two batteries have different voltages.

Apply the previous explanations in a guided problem.

Check your understanding with a short quiz.

Trace how series connections raise voltage while parallel connections raise capacity and current sharing. Use simple cell examples to predict pack voltage, amp-hours, watt-hours, and the basic tradeoffs behind battery packs.

Interpret discharge ratings such as C-rate, continuous current, peak current, and cutoff voltage. Decide whether a battery can safely supply a load, while accounting for heat, voltage sag, state of charge, and temperature limits.

Apply the previous explanations in a guided problem.

Check your understanding with a short quiz.

Review this chapter with practice based on your mistakes.