LOUISVILLE, Ky. — Intermittent fault codes on a truck are often rooted in the starting and charging system, as so much of the truck depends on the electrical system, experts said.
“The truck is changing. The compression on the engine is changing, and the speed required to make that truck crank is changing,” said Homer Hogg, director of technical service for TA Truck Service. “So [truck makers] want that engine to turn faster, and they want it to turn with more power.”
TA Truck Service is a unit of TravelCenters of America Inc. Hogg spoke during a seminar on modern starting and charging systems at the Mid-America Trucking Show here.
Looking at batteries, their reserve capacity — defined as the number of minutes a fully charged battery at 80 degrees Fahrenheit will discharge 25 amps until the battery drops below 10.5 volts — is key for trucks operating auxiliary power units, said Daniel Mustafa, assistant manager of technical development, TA Truck Service.
Traditional flooded-cell batteries, with low reserve capacity of 140 minutes, are not up to powering microwaves, televisions, refrigerators and off-duty drivers who play electronic games, Mustafa said during the seminar.
But absorbed glass mat batteries — in which the electrolyte is absorbed in glass mats instead of freely flooding the plates — pack much more power into a same-size case reinforced to take the pressure of the compressed cells, he said.
However, they are very sensitive to overcharging and require special chargers, he said. “But they have very high reserve capacity of 190 to 200” while maintaining relatively high cranking amps,
A pure lead AGM battery has the highest reserve capacity, 225 minutes, he said.
They are standard on the Freightliner Cascadia, Mustafa said. “That battery costs a fair amount, but it is very, very good technology,” he said.
Freightliner is a unit of Daimler Trucks North America.
Some of these batteries come with bluetooth technology built into the battery to diagnose the battery’s condition wirelessly from a cellphone, Mustafa said.
“So there is a lot of new stuff coming with regard to battery technology.” he said.
With advanced batteries, changes to charging systems follow.
Turning to alternators, which charge the battery power and the electrical system when its engine is running, Mustafa said they are evolving, too.
For instance, traditional brush-type alternators, with 13 more parts, are giving way to more simply designed and efficient brushless alternators.
Mustafa by John Sommers II for Transport Topics
Those are common on trucks with auxiliary power units, Mustafa said.
Also, a remote-sense alternator has a separate wire running to the battery to sense its actual voltage. “The alternator is designed to adjust its charging rate based on actual battery conditions [sensed by the small wire] rather than constantly charging the battery at a fixed rate,” he said.
In some cases, a remote-sense alternator can shorten the battery charge timing by 50%.
“Consider what that means for your battery’s life,” Mustafa said.
Meanwhile, as batteries and alternators age, then the belts and drive system, and grounds need to be reviewed in the summer and the winter, Hogg said.
“If your gauge flickers, or have intermittent problems with the electrical system inside your cab, you have a ground problem,” he said.
Hogg recommended getting a digital multimeter with a 10 million ohm range, or the ability to block current up to that level. A typical multimeter can measure voltage, current and resistance.
“Most technicians go right to the battery and test all the power studs,” he said, “but they forget the grounds.”