As commercial vehicles become ever more loaded with electrically powered systems and accessories, fleets are demanding greater battery performance.

The effect of voltage drawdown is staggering, considering the number of electrical devices -- some unheard of just ten years ago -- that are becoming common to many fleet trucks.

Fleets also want batteries with enough reserve capacity for reliable starting under heavy electrical load and use conditions and the ability to survive deep discharges.

Batteries with more starting power and deep-cycling capability are coming on the market. In most cases, the maintenance-free design remains the rule.

In general, maintenance-free batteries still rely on calcium-calcium or calcium-lead technology. Deep-cycling batteries -- aimed at trucks with power-hungry sleeper cabs -- use calcium-calcium or calcium-antimony construction and may require extra maintenance.

Bear in mind that a "starting battery" can be shot after anywhere from 30 to 60 deep discharges. If this is a potential concern, fleets may consider spec'ing new or replacement batteries that promise deep-cycling performance.

East Penn Manufacturing Co., maker of Deka batteries, now offers two Group 31 Cycle Service/Dual Purpose batteries. The maker says the batteries are designed specifically for commercial "cycling-service applications," such as multi-stop delivery and reefer-equipped vehicles.

The batteries provide 640 cold-cranking amps (CCA) at 0 degrees F for easier starting, as well as 180 minutes of reserve power for "moderate-duty cycling" in most commercial applications. Heavy-duty plates with high-density oxide help withstand "high-cycling" service.

Other features include full-frame, Compu-Cast grids that resist internal short circuits and anchor-locked elements to reduce vibration damage.

All Deka cycle-service batteries use a calcium design with flush covers and covered screw-in vents to make them maintenance-free, says East Penn, but not "maintenance-impossible." Indeed, in case of overcharging, water can be added.

East Penn has also debuted what it terms the "Deka Systems Approach" to combine starting-type and specially designed deep-cycle batteries.

According to the manufacturer, this system design will ensure sufficient power to meet power demands of auxiliary equipment while the truck's engine is off, yet provide the necessary cranking power to start the engine when it's time to hit the road again.

What's more, East Penn says this approach will provide longer, more reliable battery life, increasing vehicle productivity and reducing battery replacement costs.

There are several Deka battery systems offered. A "3 plus 1" system uses three starting and one deep-cycling battery and a "2 plus 2" system combines two batteries for starting and two for auxiliary power.

According to GNB Technologies, its Champion PC 31 maintenance-free batteries feature a longer shelf life and require less recharging time than conventional calcium batteries.

The battery is also designed to withstand the high vibrations typically incurred by shorthaul and vocational trucks. The PC 31's silver-calcium plates are anchored in polypropylene for extra stability and are isolated with polyethylene separators.

In addition, the battery case is made of high-strength Duratex plastic. Champion PC 31 batteries are available in ratings of 650, 750, and 925 CCA.

Exide Corp. says its commercial batteries feature the latest in power-storage technology. For example, the lineup includes the HC-31 High-Cycle maintenance-free series.

According to Exide, its heavy-duty batteries boast computer-designed radial grids to add power and resist vibration.

To help offset vibration, the batteries use the manufacturer's trademarked Armored-Plate construction, consisting of extra-thick plates anchor-bonded to the internal container.

A center lug design also suppresses vibration. Cases are made of reinforced polypropylene or hard rubber to weather rugged on- and-off-highway applications.

As for power performance, the batteries feature a "super-tough" separator design that Exide says "virtually eliminates the possibility of shorting, even under the roughest conditions."

In addition, the company says use of through-the-partition welds reduce electrical resistance with shorter current paths to deliver more usable power.

Exide commercial batteries also feature a manifold vent that prevents corrosion by venting gases away from terminals and cables.

On the light-duty front, Johnson Controls has introduced its Equalizer battery to combat excessive vibration and high under-hood temperatures that can cause batteries in light trucks to fail prematurely.

The Equalizer boasts extra-thick, "commercial-grade" plates that are corrosion- and heat-resistant, as well as ribbed end walls that resist vibration.

According to Johnson Controls, the battery is eight times more vibration-resistant than standard automotive batteries.

The manufacturer also states that compared to standard batteries, the Equalizer provides 20% more reserve capacity to handle extra electrical accessories. It also features a state-of-charge indicator for checking the power level.