How to Brace Your Electrical System for Winter

Winter is an equal-opportunity hazard for most truck equipment, but it’s especially hard on electrical systems. Battery power sags. Starters and alternators strain under heavier workloads. Caustic road chemicals gnaw at any exposed wiring and connections.

Trouble is always on the horizon, especially considering that roadside breakdowns in frigid, remote areas can be uncomfortable, even dangerous. Prevention, of course, is the key to lowering your risks.

Truck electrical systems are composed of three main subsystems: starting, charging and wiring. The condition of each affects the performance of all. A faulty output cable on an alternator, for example, can result in insufficiently charged batteries, which will soon cause the starter to self-destruct. Excessive amp-draw from too many electrical appliances will have the same effect.

Ken Soules, director of technical training at Leece-Neville, says most standard alternators can’t keep up with the growing number of creature comforts found in truck cabs today.

“A typical 130-amp alternator generates less than 120 amps at full capacity,” Soules says. “To make matters worse, truckers draw down their batteries at night with televisions, toaster ovens and electric blankets, then expect the alternator to recharge them the next day while the truck is going down the road and the heaters and lights are pulling 100 amps. In this situation, you’d need to drive to Venezuela before your batteries were fully recharged.”

Leece-Neville builds a range of heavy-duty alternators, but the company is probably best known for its high-output models: 160 to 320 amps. Although helpful (or necessary) in some applications, the units are just one piece of the electrical puzzle, and they cannot compensate for failures elsewhere in a system.

Several years ago, engineers at Delco Remy America decided to take a comprehensive approach to improving electrical reliability. They developed a new alternator, starter, low-voltage disconnect and batteries – collectively known as the Road Gang Premium Electrical System – designed to work best when connected to each other.

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Mike Crull, account manager for Delco Remy America, says each Road Gang component contributes to the longevity of the others: The alternator uses remote-voltage sensing to compensate for cable volt drop and to keep batteries properly charged. The starter has over-crank protection and other features to help prevent meltdowns resulting from excessive cranking. The low-voltage disconnect – a device drivers love to hate because of its unpredictable interruptions of in-cab power use – preserves battery power for engine starting. And the batteries, with 700-amp cold-cranking capacity and 190 minutes of reserve capacity, deliver ample energy for both engine starting and appliance needs.

This beefed-up technology obviously has the potential to reduce unscheduled downtime. Truckers, however, can have as good an impact, if not better, with regular preventive maintenance. A good PM program should include the following:

A coat of dielectric grease helps prevent corrosion from starting in light sockets. It also makes bulb removal easier.


Ensure alternator is delivering enough power. With your truck’s engine off, turn on all electrical devices (heater fans, lights, etc.). Hang a clip-on ammeter on the main positive cable going to the batteries. Check the readout and add 15 or 20 amps if the truck isn’t attached to a trailer. Then add another 15 amps for each starting battery. The total should be equal to, or slightly lower than, your alternator’s rated amp output, which is indicated somewhere on the housing. If the ammeter reading exceeds your alternator’s rated output, you should start shopping for a beefier model that will handle the load without working itself to death.

Check belts. Closely inspect the alternator belts, for cracking, chaffing and fraying. Replace anything that looks marginal. Mechanics suggest swapping any molded double-V belts with a new matched set of singles. The double-V design prevents belts from sinking to the bottom of a worn pulley, eventually resulting in slippage.

Test alternator performance. Locate your alternator’s output-cable terminal (usually marked with a +). Start your truck’s engine and run it at an idle. Set a multimeter to DC volts and secure its ground wire to a nearby piece of truck metal, such as a frame rail. Touch the meter’s positive probe on output-cable terminal. If the batteries are fully charged, the alternator should be generating 14 to 14.5 volts. The voltage output should remain fairly constant, regardless of engine speed. If the actual output is more than 10 percent below or above the voltage target – roughly 13.2 volts on the low end and 15.5 on the high end – you’ll need to invest in a new alternator.

Check for volt drop. Repeat the previous volt test at the batteries, grounding the meter and touching its positive probe on the main positive cable. With the truck’s engine running, the amount of voltage reaching the batteries should be within a half-volt of that generated by the alternator. A difference greater than one volt indicates looming trouble in the alternator’s output cable or its connections. You might be able to resolve the matter with a thorough disassembly and cleaning. If that doesn’t fix it, you’ll need a new cable.


Load test batteries. Remove the batteries from your truck and inspect them for leaks, damage and bloating. Make sure they’re all fully charged and take them to a shop or auto parts store to be load tested.

Inspect and clean cables. Unbolt the battery ground cable from your truck’s frame and check the ends for cracks, fatigue and corrosion. Then check the other cables and cable ends. Clean all ends with a steel brush and replace any marginal parts. Install the batteries and attach and tighten the cables. Apply anti-seize compound to the frame-mounted ground’s bolt and use a commercial sealant to protect the battery terminals from corrosion.

Corrosion, a colorful and natural chemical reaction, is almost always present inside a battery box. Although you can’t stop it, you can slow its growth and limit its damage by regularly disassembling, inspecting and cleaning battery posts and cable ends. Once corrosion starts building up inside a cable end, the part must be replaced.


Seal wiring. Bare copper wiring rots fast, and even faster when moistened with road chemicals. Sealed wiring doesn’t rot, usually. It’s impossible to keep a truck’s wiring harness totally sealed. But with persistence, an assortment of silicone products and plenty of heat-shrink tubing, you will be able to limit the crawl of bluish-white powder, the calling card of electrical corrosion. You should routinely look for potential trouble spots (light-fixture mounts, connections, chaffed or cracked wiring) and seal any area that threatens to expose the submerged wiring. It’s also wise to coat all bulbs and plug-ins with dielectric grease before installing them.

Secure wiring. Loose, hanging wires should be secured with cable ties. They should be further protected from nearby metal objects with lengths of old heater hose or wire loom, sometimes called gator wrap.

Check and clean ground straps. It’s important to periodically remove and clean the contact surfaces of frame-mounted ground straps on your truck. Corrosion commonly accumulates under the bolt and nut, causing problems for electrical components. Be sure to apply anti-seize compound to the bolt before reassembly. That will make disassembly much easier the next time.


Avoid abuse. Cold weather is doubly tough on starters. It makes engines harder to turn while lowering the available amount of battery power. Starters require no preventive maintenance, outside of tight bolts and cables. Their longevity is mostly determined by the way they’re operated. Excessive cranking – defined as more than 15 continuous seconds – and low battery voltage will quickly melt a starter’s internal organs, giving it boat anchor status. You can avoid this disappointment by preheating your engine before starting, when possible, and giving your starter a minute (or two) to cool between cranking intervals, when necessary. Also, if your starter begins making a clicking sound, the sign of a power-starved solenoid, consider it Morse Code for: Stop twisting the key!