This complete indroduction to the 12-volt electrical systems used on small boats to power everything from reading lights to bilge pumps is written for boaters who are not skilled electricians. It explains how 12-volt systems work, how to maintain them in a good operating condition, how to recognize an electrical problem and how to troubleshoot that problem. This second edition has been updated to include the latest on marine batteries, charges, inverters, new wiring conventions, alternative energy sources and modern test gear.