Overview
This lecture explains the basics of electricity for beginners, focusing on volts, amps, and watts, how to calculate them, and their significance in designing electrical systems such as solar power setups.
Basics of Electricity
- Electricity travels through conductors (wires) covered by insulators for safety.
- DC (Direct Current) flows in one direction; like a river from positive to negative terminals.
- AC (Alternating Current) oscillates back and forth; like a wave, not physical flow.
Understanding Volts, Amps, and Watts
- Voltage (volts) is the electrical pressure or force, like water pressure in a hose.
- Amperage (amps) is the amount of electricity flowing, like the thickness/flow rate of water in a hose.
- Watts represent total power and are calculated by multiplying volts and amps: Watts = Volts × Amps.
- Appliances must match the voltage of the power source for compatibility.
- Larger wires are needed for higher amperage to prevent overheating and fire.
Watt Hours and Battery Storage
- Watt hours (Wh) measure how much power is used or stored over time (Watt × hours).
- Battery storage is often described in amp hours (Ah) at a specific voltage; multiply Ah × V for watt hours.
- To find how long a battery powers a device: divide battery Wh by device wattage.
Series and Parallel Connections
- Connecting components in parallel increases amperage, voltage stays same.
- Series connections increase voltage, amperage stays same.
- Combine batteries or solar panels in series or parallel to get desired voltage/amperage for a system.
Designing a Solar Power System
- Add amp hours of batteries in parallel for total capacity, then multiply by voltage for watt hours.
- Only half the capacity of lead acid batteries is usable for longevity.
- Total solar panel wattage divided by system voltage gives required solar charge controller amperage (size slightly higher for safety).
- Charging time = usable battery watt hours divided by average solar panel output per hour.
Fuse and Wire Sizing
- Choose wire gauge based on load amperage and distance, using wire gauge charts.
- Fuse size = 1.25 × load amperage for safety.
- Use copper wires for accuracy and better conductivity.
- Fuses are protective devices that disconnect circuit if current is too high, preventing fires.
Key Terms & Definitions
- Voltage (Volt) — Electrical force or pressure in a wire.
- Amperage (Amp) — Amount of electric current flowing through a wire.
- Watt (W) — Total electrical power; product of volts and amps.
- Watt Hour (Wh) — Measurement of power consumed or stored over time.
- Parallel Connection — All positives and all negatives connected; increases amps.
- Series Connection — Positive of one to negative of next; increases volts.
- Fuse — A device that protects circuits by disconnecting when current exceeds a set value.
- Wire Gauge — Thickness of a wire, determining how much current it can safely carry.
Action Items / Next Steps
- Look up a wire gauge chart for your specific load and distance.
- Practice calculating wattage, ampacity, and fuse size for different appliances.
- Review battery manufacturer data for accurate amp hour ratings.
- Read about the Peukert effect if detailed battery discharge rates are needed.