Several major industry trends are helping shape today's truck alternator. First, stricter emissions regulations in 2002, then again this year, have spawned a new generation of hotter running diesels. There has also been a significant increase in electrical loads being put on today's trucks, and anti-idling laws are becoming more commonplace.

To address the issue of added heat under the hood, Delco Remy has been increasing the temperature ratings of both its brush-style and premium brushless alternators. Tim Barnes, Delco Remy's aftermarket product manager, reports that the 28SI brush-style alternator, scheduled for OE Production during the last quarter of 2007, is being built on the same DIF (dual internal fan) platform as the 24SI model, except the temperature rating will increase from 105-deg. C to 125-deg. C.

A 125-deg. C rated brushless alternator — the 36SI — is currently available from Delco Remy. It too, Barnes states, was increased from a 105-deg. C rating to meet the hotter running 2007 engines. Pre-2002 models, he noted, were rated at 93-deg. C, which shows just how much alternators have had to evolve to keep up with each new tier of engines. In 2008 the company will release the next generation brushless alternator — the 40SI model — which will have a significantly higher output rating.

“While cooling the operating temperatures of our alternators, we've simultaneously increased the amp ratings of our brush and brushless alternators to support the higher electrical loads on trucks,” explains Barnes.

He says when the new 28SI model becomes available later this year, it will offer an output in the 180-amp range with 120 amps at engine idle. The brushless 36SI is rated as a 160-amp alternator with 110 amps at idle.

According to Rick Hehman, marketing director of Delco Remy, all Delco Remy alternators use a unique technology called Remote Sense. It improves charge because it regulates voltage directly at the batteries, he explains. “Studies have proven that with Remote Sense technology, we can reduce the time it takes to charge a battery by 50%. ”

Dave Stone, executive director, Powertrain & Chassis, Mitsubishi Electric Automotive America (MEAA), says that in addition to increasingly higher vehicle hotel loads in trucks, 2010 emissions regulations will also require the development of alternators with greater electrical output. “New alternators will also be designed to better deal with excessive heat from these engines.”

Eric Karr, heavy duty account manager, MEAA, adds: “As the industry moves toward meeting the even stricter 2010 emissions standards, we are working with truck OEMs to determine their requirements so we have the best designed, engineered and highest quality alternators on the market.” He notes that Mitsubishi Electric heavy-duty truck alternators are all brushless for better performance and longevity, are pad-mount for reduced vibration, and are designed to provide the greatest output-to-mass ratios for better fuel economy and increased payloads for fleets.

Earlier this spring, Leece-Neville Heavy-Duty Systems Division of Prestolite Electric announced a redesign of its high-amperage, high-temperature 4000 series alternators, including a solid lead frame for rectifiers that greatly reduces the number of wiring connection points within the alternator. The manufacturer also released a new 185-amp brushless model, initially approved for applications up to 110 deg. C. Leece-Neville says units with a rating of 125 deg C. will become available later this year.

Robert Bosch LLC, which manufactures the Long Haul alternator for commercial vehicles, just introduced a new model especially for the school bus market. The AL9962SB Long Haul alternator provides a maximum output of 200 amps, the company reports, to accommodate buses which often have installed electricity-eating accessories like chair lifts and operate them with the engine at idle. And like Bosch's AL9960LH and AL9961LH truck alternators, the school bus model also incorporates a 125-deg. C temperature overload cutoff.

This feature “is ideal for commercial vehicles in a lot of stop and go driving,” says Lee Reighart, group product manager, starting & charging products for Bosch, explaining how the temperature cutoff allows the alternator to come back producing current immediately as the temperature drops below 125 deg. C. The Long Haul alternator, he notes, operates at 70% efficiency, produces 160 amps output at 80 amps idle, and can replace more than 220 different OE models.