Avoiding the Pitfalls and Gremlins of Charging Systems
Often taken for granted and rarely inspected, the charging system in today’s modern performance vehicle is responsible for keeping the battery fully charged and supplying the proper amount of voltage to the electrical system. This sounds relatively simple, but charging system problems are often unpredictable. And when they occur, they can quickly cause a myriad of problems from dimming lights to even a stalled engine and dead battery.
The 12-volt automotive charging system consists of an alternator, battery, charge wiring and ammeter/voltmeter gauge or indicator light. While most late model vehicles have the voltage regulator built into the alternator, many early models located the regulator externally. Mounted either on the firewall or inner fender well. The “heart” of the system is the alternator. Which includes the rotor, stator, rectifier, and voltage regulator. Fastened directly to the alternator pulley, the rotor spins within the fixed stator assembly, producing Alternating Current (AC), similar to the power used in homes. The AC is then converted to Direct Current (DC) through a series of diodes that are specially arranged within the rectifier. At the same time, the voltage regulator maintains the DC at 13.5-14.8 volts as it is fed via the charge wire to the battery and throughout the electrical system, ensuring that all system components function correctly.
When searching for an alternator, it’s important to know that the chosen unit offers sufficient amperage for the intended application. After choosing the proper alternator, it should be rigidly mounted to the engine, properly grounded, and fit with the correct diameter pulley so that it will operate effectively within its specified power curve. Powermaster recommends that circle track applications use a pulley ratio of 1:1, while drag racers need approximately 1.75:1 and street-driven vehicles require 3:1-3.5:1. Powermaster offers a full line of high-performance alternators.
The alternator drive belt has to match the pulley for correct type (V-belt, serpentine, or HTD), width and length, and be tightened properly so that it does not slip. To ensure that the belt is tight enough, apply a 1/2” breaker bar with the necessary socket on the nut that secures the alternator pulley and attempt to rotate the pulley in a clockwise rotation. If the engine begins to turn over and the belt does not slip, the belt is tightened sufficiently.
One of the most common pitfalls of charging systems is using an alternator charge wire that is of insufficient size. This is particularly concerning on race cars where the battery has been relocated to the rear of the vehicle, requiring a longer and heavier gauge wire than would be required for a front-mounted battery. Basic automotive electric wiring principles require that wire diameter be increased when length is extended or amperage is increased. If the charge wire is of insufficient size, it can cause a condition referred to as “voltage drop”. This condition can often become the source of a hard to diagnose electrical “gremlin”, caused when the wire is overloaded and subsequently overheats, leading to system shorts or even potentially causing a fire. All charge wire terminals should be crimped and soldered to ensure positive connections.
The battery also plays an important part in the equation. If battery condition is in question, it can be quickly checked using a battery load tester. If the battery requires charging, care should be taken to ensure that the charger is truly compatible with the battery.
With the availability of lead-acid, gel, AGM, and lithium-ion models, mismatching batteries and chargers is a relatively recent problem that can significantly shorten battery life. Braille, Lithium Pros, Odyssey, Optima, Turbo Start, and XS Power are good sources for high-performance batteries and chargers. Battery cable lengths should be as short and direct possible, using four-gauge if the battery is located in the stock under hood position, while two- or zero-gauge is preferred if the battery has been relocated to the trunk. QuickCar offers a full selection of premium battery cables and highly conductive, gold-plated battery terminals when an upgrade is desired.
The system may be closely monitored using a permanently installed voltmeter. Available from vendors including QuickCar, Allstar Performance, and Auto Meter, a voltmeter provides instant notice to the driver in the event of a problem, while also aiding system diagnosis.
Often ignored or overlooked until there’s a problem, the key to reliable charging system performance is not only choosing the correct, quality components, but also ensuring that the associated wiring is correctly sized, installed, and terminated.