One night in November 1965, a simple relay in upstate New York’s power system failed. The outage marched eastward from Niagara Falls and engulfed New York City and New England.
Today’s truckers can experience similar overloads. More operators shut down the diesel overnight to save fuel and conform to environmental standards, and they also use more electrical appliances than before. The result in the morning is often the same empty feeling New Yorkers had that dark evening in 1965.
Trucks, though, have a major advantage over electric utilities, whose generators must constantly turn to make electricity: batteries. Knowing the right kind of batteries to install and managing use of their power will keep the tow truck away.
“We have begun to put everything you can conceive of into that cab – radios, CBs, televisions, microwave ovens, heated waterbeds and so on,” says Delphi Corp. engineer Tom Julian. In a truck shut down for the night, this puts the wrong kind of stress on the batteries. Furthermore, “The marketing people for some reason began to perceive that the higher the CCA number, the better the battery,” Julian says, but that’s a mistake.
CCA is cold cranking amps, one of two universal measurements of battery performance. CCA measures the number of amps a battery can supply at 32 degrees for 30 seconds with the voltage dropping to 7.2. The other measurement, reserve capacity, is how long it takes for the voltage of a fully charged battery at room temperature, supplying 25 amps, to drop to 10.5 volts.
The push for high-CCA batteries doesn’t make sense because of improvements in starting, says Julian. “As we adopted onboard computers that could advance injection timing for starting and better injection systems and the like, diesels, which had once required long crank times, became easy to start.” Nevertheless, “People remembered the hard starting and wanted high CCA batteries.”
To make matters worse, as battery performance improved, truck makers reduced the standard equipment complement of batteries from four to three. That saves weight, space and dollars, but it creates another problem. “We have a certain size cell we have to work with,” Julian says. “To get high CCA, we need 21 plates to give more surface where metal contacts acid. This makes those plates very thin.”
You get high CCA with all those plates, but the voltage drops off rapidly, and the life of the plates is much shorter than it should be. You also get much less reserve capacity than if you had, say, 15 much thicker plates – typical of a battery with more RC and less CCA. Julian says 21-plate models typically have only a third of the life of a 15-plate battery. “These days, batteries get blamed for a lot of troubles, but actually the problem is that they’ve been misapplied.”
This Xantrex inverter/charger operates house-current appliances off the batteries and it charges the batteries when you’re plugged into shore power. A factory-installed system, which includes premium features, costs $2,000 in Freightliners and Internationals, $1,500 in Volvos.
The ideal would be a battery with about 700 CCA, rather than some of today’s units, which go as high as 1,000 CCA. An RC of 200 minutes would be ideal, but Julian says “about the most you can get is 170-190 with a 700 CCA battery. With a 750 CCA battery, you can get only a 150-160 RC rating.” He says it’s best to match CCA with the engine size because an unnecessarily high CCA can actually burn out solenoid contacts with an initial power surge. Only very large diesels require more than three 700 CCA batteries. If you need more CCA than that, rather than installing three 750 or higher CCA batteries, considering installing a fourth 700 CCA battery.
If you have doubts about the importance of RC over CCA, consider this: Julian has found key-off parasitic losses from onboard electronics so high on many trucks that four 180-minute RC batteries will run down to the point where the truck won’t start if it sits for six days.
A battery with about 16 plates is “the best of both worlds,” says Bruce Purkey of Purkey’s Fleet Electric, a consulting business for fleets with electrical problems. He calls such a battery a “multi-purpose, combination, or high-cycle” unit. Strong cycling ability means the battery can handle running in-cab accessories every night and still last a long time. “Higher CCA batteries have thicker plates and limited cycling ability,” Purkey says.
There was a trend for a while of using separate, deep-cycle batteries alone to power cab accessories. This has faded because taking all the engine-off power from only a portion of the batteries led to early battery failure.
Whether the engine is off or on, Purkey and Julian say it’s critical to manage power consumption. Shut off everything you can as soon as you stop the truck, rather than leaving headlights or even the dome light on for even a short time. Both endorse low-voltage devices, which are designed to prevent running the batteries down to the point where they will be damaged and the truck won’t start. But, Purkey says, you’ve got to solve your battery problems first. He says the short-life, low RC problem can be so severe that a high CCA battery that’s only a few months old can fail to start the truck even when an LVD is working properly.
Just because the engine is running doesn’t mean there is an excess of power to recharge the batteries. “Don’t write your name in chicken lights on the side of the truck,” Purkey says. Even when the alternator and regulator are working right, the batteries get only what’s left over after all the accessories are powered.
He adds, “Because of such accessories, many an owner-operator truck uses all but 30 amps of the alternator’s output to operate the truck; a typical fleet truck usually has 60-70-amps left over.” You might find that the batteries don’t charge up even during a full day’s drive. If you find shutting off accessories takes your voltmeter from the yellow area into the green, it’s an almost sure sign your alternator is working, but doesn’t have enough capacity.
The Xantrex-Delco 1750-watt inverter/charger is marketed through Delco Remy and sells for $499. A 1000-watt model goes for $349.
You can, of course, put on a bigger alternator. But, Purkey cautions, “Have you got money to burn? It takes 9 horsepower to run a 200-amp alternator. It’ll sure affect your fuel economy.”
To eliminate no-starts, don’t fall for any myths of the road. You don’t need high CCA just because some people say you do. And you don’t need to light up the sky with the lights on your rig. Use restraint in fitting electrical accessories onto your truck and fit the right type of batteries in sufficient number. Remember to shut things off when they aren’t needed or at least manage your power with an LVD. You’ll end up with reliable starting and long battery life.
Bob Maddox, co-owner of Nick and Dees Trucking in Hereford, Texas, says modern diesels don’t need much cold-cranking amps except in severe climates, so he fits his trucks with four high reserve capacity batteries. His trucks have few no-starts, even though idling is kept to a minimum.
Maddox also uses refrigerators in his trucks that have their own low voltage devices to shut them off – good for both batteries and the fridge, though he’s been known to lose a sandwich now and then. Since his trucks spend more than half their downtime in the fleet’s yard, he keeps each plugged in to a trickle charger whenever it’s home. Even when the drivers use the microwave or the television for short periods, the charger has time to get the batteries topped off before the truck leaves on its next journey. The trucks are also equipped to use truck stop shore power when it’s available.
Like Maddox, you can use technology to manage your power drain – and not just for one appliance. Brian Lawrence, heavy-duty truck manager at Xantrex Technology, says his company makes a lineup of heavy-truck inverters that cut off cab power at 12 volts so the truck will be sure to start. They give a warning 30 to 60 seconds before the unit kills the in-cab power.
Xantrex inverters are actually inverter/chargers. They not only convert 12-volt DC to 60-cycle AC for in-cab use, but when you plug into shore power, they convert 60-cycle AC back to 12-volt DC. This means you get a thorough battery charge when you plug into shore power overnight. Lawrence believes this feature is particularly helpful. “Although alternators are good machines, the regulator on an alternator is designed for cost purposes and is really just a bit crude. In normal truck operation, batteries never get fully topped up.”
Bruce Purkey of Purkey’s Fleet Electric suggests a remote-sensing alternator, which senses voltage at the battery’s positive post, to help with this inadequacy.
Intra Technologies Vice President Will Watson notes the consequences of not cutting off in-cab power at 12 volts can be more severe than most operators realize. You get longer cranking times with starter stress and engagement problems, battery sulfation (which greatly shortens their life), and even shorter alternator life. The latter occurs because the alternator works too hard trying to charge a very low battery. Protecting the electrical system from low voltage, which is often not obvious to the driver, can reduce alternator costs alone by 30 percent, he says. Yet many trucks are loaded with in-cab appliances powered by an inverter with no low-voltage protection.
Intra’s low-voltage devices also cut the power off to protect batteries. At 12.1 volts, the driver gets a short, audible warning. This continues at intervals for more than 5 minutes, giving the driver “time to pop his popcorn,” as the company puts it. Or if the driver turns off loads, the warning stops until things get critical again. The driver even gets a warning if he’s cruising down the road and the alternator quits charging.
Watson says there aren’t any factory-installed LVDs, and those in the aftermarket aren’t “retrofit-friendly.” Intra makes kits for specific truck models for all the major truck brands so they can be installed efficiently.
