Market demands starting reliability, deep cycling.

With the profusion of on-board computer controls for engines, transmissions, and brakes, the amount of "key off" power loss has risen dramatically -- from the milliamp range of years ago to losses that now exceed 5 amps/hr. At that rate of discharge, a tractor's batteries can be reduced to about a 65% state of charge in only 10 hours. In other words, over a long weekend a truck's batteries can deplete to the point whereby a jump-start would be needed Monday morning.

Further complicating this is the profusion of TVs, VCRs, refrigerators, and other creature comforts that longhaul drivers are demanding. Use of these devices can literally steal the life from batteries during off-duty, non-driving times.

Truckload fleets first began attacking this problem with isolated battery systems, protecting starting batteries by reserving one and sometimes two batteries -- deep-cycle models -- for the driver's use. To protect the starting batteries from drawdown, a more recent approach is a low-voltage disconnect that allows all four batteries to be used for driver purposes, but only until they are drawn down to 65%.

Battery manufacturers are responding to truck operators' needs with an increasingly sophisticated range of products, including some with extra starting reliability and others with deep-cycling capability to withstand heavy use.

For the majority of applications, maintenance-free batteries are available, some of which allow water to be added when necessary. These are generally of calcium-calcium or calcium-lead construction. Deep-cycling batteries for sleepers -- calcium-calcium or calcium-antimony construction -- require some additional maintenance.

Since a typical starting battery can be ruined after only 30-60 deep discharges, ACDelco produces a range of maintenance-free, heavy-duty cranking batteries that are also designed for better cycling application. The Freedom range includes the 1150-1151 High Cycle, claimed to be the first maintenance-free battery with high cycling capacity; the S2000, a deep-cycle flooded cell unit designed for sleepers; and the DC-31, which provides a greater number of deep-discharge cycles.

Mixon's Daystarter batteries are maintenance-free and come with a three-year free-replacement warranty in the event of failure in commercial service. A more common industry practice is to pro-rate battery replacement values according to how much of the battery's life has been used prior to failure.

Douglas Battery Manufacturing produces a line of heavy-duty diesel-starting batteries that are designed and manufactured under a TUV-certified quality system based on the international ISO 9001 standard. This includes calcium-calcium, calcium-hybrid, and low-antimony designs for a broad range of applications. Douglas also offers a 31 Fleet Series suited for high-mileage applications that is claimed to provide longer life and greater durability than other Group 31 batteries.

Dynacell says its objective is not only to sell products, but to work with customers and analyze their needs. The company says it has reduced customers' battery purchases and expenses by 50%, on average. For most commercial accounts, it recommends a calcium, maintenance-free starting battery. For sleeper-specific applications, Dynacell offers a deep-cycling auxiliary battery with lead-antimony plates. This product has the ability to take a deeper discharge, but again requires more maintenance than a calcium battery.

East Penn Manufacturing, which makes Deka batteries and accessories, has developed a system that combines starting batteries with specially designed deep-cycle batteries in different configurations, depending on need. For example, a "3 plus 1" system matches three starting and one deep-cycle battery. A "2 plus 2" system matches pairs of both types. Starting batteries are calcium and maintenance-free, while deep-cycling batteries contain gelled electrolyte.

GNB Technologies has introduced a new maintenance-free battery line, PC 31, designed to survive in the high-vibration environment of construction operation. Its plates are anchored in polypropylene for extra stability and insulated with durable polyethylene separators. Cases are made of a rugged plastic called Duratex. If the battery overcharges, which could cause electrolyte gassing, water can be added to the electrolyte.

GNB has also introduced the Champion PC isolator system, which consists of two deep-cycle isolator batteries, two starting batteries, and a jumper cable.

Johnson Controls is about to introduce a radically new starting battery made with tightly wound thin metal film technology that packs 20 times the power density of conventional storage batteries. The compact truck battery (6x5x4 in.), which will weigh only 6 lb. -- two or more need to be hooked up in parallel -- has high internal conductivity. These batteries will provide an intense burst of power to spin cranking motors and start diesels quickly. According to the company, use of the product could save upwards of 100 lb. of tare weight, thus increasing truck productivity.