Electrical Repair: How To Diagnose & Repair Your Charging System Part 1

The charging system in your vehicle can be thought of as a small power plant which helps to supply the necessary electrical current in order to operate your vehicle and its accessories. With the ever-increasing complexity of today’s cars, trucks, SUVs and other vehicles, the role of the charging system is now more important than ever.

The charging system normally consists of three major components: An Alternator (or in some cases a Generator), A Voltage Regulator, and the associated wiring which connects the output of the system to the battery for charging. Most consumer vehicles built within the last 30 years or so use an alternator with the regulator built in.

Strictly  speaking, the purpose of the charging system is to do just what its name implies; charge and maintain a full charge on the vehicle battery or batteries. Therefore, the first important thing to realize is that in order for the charging system to work correctly and reliably, a good battery is essential.

If you are experiencing symptoms such as slow engine starting, dim lighting, and/or frequent dead batteries, the first place to look for trouble is the battery itself. The battery should be fully charged before performing any  tests. The best way to test a modern car battery is to use a Load Tester, a device which is made for the purpose. Such a tester will apply a constant electrical load(usually equal to one-half of the battery Cold Cranking Amp or CCA rating)to the battery for a specific amount of time, usually 15 seconds. Some advanced models of battery testers have a built-in database which contains CCA rating information on many types of batteries.

The battery tester will usually have a meter or some other indicator which shows whether or not the battery is good.

Most auto parts stores, repair shops, and even some large department stores can quickly perform this test, and will often do it for free if you take your battery to them for testing. You can also perform the test yourself if you buy or have access to a battery load tester.

Another type of test which can be used for non maintenance-free batteries uses a device known as a Battery Hydrometer. This instrument is used to measure the specific gravity of the chemical electrolyte inside the battery, thereby indicating the state of electrical charge. Nowadays, the above-mentioned load test is the preferred testing method because it works very well and unlike the Hydrometer test, it doesn’t involve any exposure to the liquid battery electrolyte.

In the next part of this series, we’ll discuss the alternator and regulator and methods for troubleshooting them. Go To Part 2