Fleet Management News & Business Info | Commercial Carrier Journal
Issue link: https://read.dmtmag.com/i/85369
Staying in charge in focus: ELECTRICAL SYSTEM MAINTENANCE T Attention to detail will prevent no-starts, power loss BY JOHN BAXTER he same electrical system symptom can signal a problem in several dif- ferent areas. When doing maintenance or troubleshooting, technicians always should avoid focusing on one or two components and inspect the entire sys- tem. Many assumed alternator or battery problems actually may be problems with wiring and connections. replace a $4 battery cable than an $80 battery when the cable is actually the problem." – BRUCE PURKEY, "It makes a lot more sense to PURKEY'S FLEET ELECTRIC Battery maintenance Some experts say that alternator maintenance is really more about maintaining the batteries than the alternator itself. A good alternator will last indefinitely if it doesn't overheat; to keep that from happening, keep the batteries working efficiently. The alternator's main job is to handle the vehicle's electrical load, with 75 percent or more of its output intended for that purpose. New batteries and good wiring reduce battery charging needs and make the alternator's life a breeze. But as batteries age or when cables and con- nections develop resistance, the alternator has to work harder and longer to replace what's used for starting or supplying overnight hotel loads. "The weak link is the 'key off' situation," says Randy Walker, director of North America aftermarket sales for Phillips Industries. "You draw a lot of energy out of the batteries while the alternator is idle. If you don't have strong cables and connections, you'll never get all that energy replaced the next day. " Batteries also deteriorate with wear and become inefficient, which means more power from the alternator over a longer period of time is needed to charge them. Higher loads and output mean more resistance and internal heat, so testing batteries to monitor their condition is critical. Batteries should be load-tested at least once a year, preferably just before the weather gets cold, as a temperature drop both reduces battery output and makes the engine harder to crank. While this test will help ensure reliable starts, it's harder to determine whether or not batteries gradually are starting to tax the alternator by losing their reserve capacity. "Batteries that pass a load test may still have lost a significant amount of their reserve capac- ity, " says Bruce Purkey, president of Purkey's Fleet Electric. To check this, establish a baseline for good batteries by testing them when new. Turn off the engine, measure battery voltage and then turn 32 COMMERCIAL CARRIER JOURNAL | APRIL 2012 Most trucks today use batter- ies with thicker plates that have more reserve capacity. While this lessens crank- ing power, these batteries are more durable when power is drawn down overnight to eliminate idling. on the headlights; let the lights drain the batteries for 30 minutes, and then retest the output voltage and record the reading. After a year or two, repeat the test; if the older battery's voltage drops more in 30 minutes than when it was new, the battery is losing reserve capacity. While conventional batteries require regular additions of distilled water, they are easier to test. Techs should fill the cells monthly for maximum performance and life; during this service, the top surface of every bat- tery should be wiped off to reduce the loss of charge during shutdowns. Maintenance-free batteries have an indicator that changes color when they deteriorate. Twice a year, technicians should dis- connect the battery connectors on each vehicle and use a powered brush to clean both the inside diameter of each connector and the post. Reconnect all connections securely and protect them with dielectric grease or a spray protectant. Typical soft lead connectors continually stretch; the fastening bolts should be tightened during monthly visits to the shop to ensure maximum conductivity. In cold weather, a jump- start may not be enough to get the truck ready for a shutdown only a few hours later. "It can take as long as two days for batter- ies to become fully charged in winter, " Purkey says. To bring a discharged battery to its full 12.6-volt charge, use a battery charger at a low rate for 18 to 24 hours. The alternator is