Fleet Management News & Business Info | Commercial Carrier Journal
Issue link: https://read.dmtmag.com/i/85369
not designed to power the truck under conditions that also require heavy bat- tery charging, so an electric charger also helps lengthen alternator life. All wired up When truck owners believe they have a charging or battery problem, the battery cable often is the culprit. When checking batteries before cold weather, also check the cables. The Technology and Mainte- nance Council's Recommended Practice 129 recommends a voltage drop of .5 volts at 500 amps of current flow. Have a professional test each cable with a special instrument that uses electronics to measure resistance; in four seconds, a specialist using such a device can tell whether or not a cable needs to be replaced. A technician can do this in a shop without a tester by measuring volt- age at the starter positive connector while the engine is being cranked by someone else, then taking a similar measurement at the battery positive terminal; he then needs to subtract the first reading from the second. "It makes a lot more sense to replace a $4 battery cable than an $80 battery when the cable is actually the problem," Purkey says. Corrosion often develops under the cable's insulation, so it's normally invisible. Phillips' cables and battery jumpers have clear jackets. "This way, your technicians can see corrosion developing, " Walker says. Current travels on the wire's surface, and if corrosion attacks and pits the surface, the cable gets smaller rapidly. "Technicians often replace the battery when the problem is the cable," he says. "Cables, wires and terminals are the weak links in the system." Technicians should check wiring quarterly or whenever they see green corrosion developing on connections. "If you can see green, there is more of it from corrosion that is still invisible," Purkey says. Water containing road salts often wicks through the cable under the insulation, corroding the entire cable. Starter and alternator positive and ground connections and any ground wires on the chassis need to be checked to make sure all connections are both clean and tight. Techni- cians also should check for cracked or frayed insulation or rubbing against other parts, repair bad wiring and protect longer runs with ties to keep them away from surrounding surfaces. 34 COMMERCIAL CARRIER JOURNAL | APRIL 2012 Write 237 on Reader Service Card or visit ccjdigital.com/info