Winning the Power struggle
48 Commercial Carrier Journal December 2008 W ith overnight shutdowns becoming more and more the rule, it's more impor-tant than ever to enable the driver to rely on the truck's ability to start in the morning. The most critical part of ensuring alternator and starter reliability, experts agree, is proper testing and maintenance of the entire electrical system. A common problem that we see is that the vehicle's charge/start system is not analyzed and viewed as a , says Eric Karr, national account manager for Mitsubishi Electric. Each component's performance affects the operation and longevity of the other components within the system, and focusing only on one component often results in a misdiagnosis or repeated failures before its design life has ended, Karr says. Fleets should use the appropriately rated alternator for its application to ensure the product's longest pos-sible life, says Orlando Braga, senior application engineer for Denso Sales California. They also should check battery condition regularly and dis-card batteries that no longer take a charge or show physical wear, Braga says. Also, checking for proper cable connections in the charging system including the alternator, starter and battery as well as replacing old cables that are worn and create high resistance can ensure correct alternator life, he says. Many problems with the alterna-tor have their source from elsewhere within the electrical system, says David Canfield, director of global marketing for Leece-Neville, a divi-sion of Prestolite Electric. It is important to consider the entire system when developing your pre-ventive maintenance program, Canfield says. The alternator, starter motor, battery, cabling and all of the electrical loads make up the electri-cal system, and an issue anywhere within that system will affect the life expectancy of all the individual com-ponents within that system. Troubleshooting tips Worn batteries take more energy to recharge than good ones, and doing so also increases the alterna-tor's operating temperature. The alternator's internal resistance increases with temperature, reducing its output, so bad batteries quickly snowball into a serious shortening of alternator life. Checking and replacing alterna-tor belts, ensuring the correct ten-sion, and using the correct alterna-tor pulley and belts also will help ensure the correct alternator life, Braga says. A slipping belt creates tremendous heat, which the steel shaft carries to the bearings, causing the grease to boil off and resulting in almost immediate bearing failure. High cable resistance can lead to chronic undercharging of batteries, which shortens their service life and requires frequent replacement, Karr says. By properly understanding the start/charge system as a whole, the offending component can be identi-fied and corrected. In this case, it's a wiring issue. Mitsubishi has devel-oped technician training materials that are available on the company's website, he says. Technicians also should make sure the cabling size is adequate for the loads expected, Canfield says. The cabling size will need to be increased any time an alternator with addi-tional output is installed, he says. It's like installing a water pump on a garden hose you're only going to get so much water through a hose of a given size. WINNING T H E P O W E R S T R U G G L E Keep your trucks moving by catching electrical problems early and spec'ing the right alternators and starters. By John Baxter Denso's product lineup includes its Y con-nection brushless alternator and R5.0 starter.