Introducing the Absolute Best Air-Cooled Alternative to Oil-Cooled Alternators

The Delco 24volt 270amp 50DN oil-cooled alternator was originally designed in the 60’s and has been a workhorse in the transit bus & coach industries going on 60 years. Tried and proven though outdated, versus the new technologies available today.

Almott is also an Original Equipment Manufacturer (OEM) and has an air-cooled 25AT-350 Series of alternators to replace the Oil-Cooled 50DN alternators.

These 24-volt 350-amp alternators are an environmentally friendly alternative that provides higher output than the 270-amp oil-cooled 50DN.

Red Bus

There are huge benefits and cost savings to be had:

  • Eliminates the environmentally hazardous oil leaks frequently associated with the 50DN alternator.
  • Greater fuel economy due to a higher 85% efficiency rating.
  • Higher output throughout all engine speeds.
  • Higher output at engine idle where it really counts.
  • Isolated ground to eliminate ripple voltage that can affect computers and electronics.
  • 3-year unlimited mileage warranty. (best in the industry

Are There Other Air-Cooled Alternatives Available?

Yes, there are so why choose the Almott 25AT-350?

  • An original design manufactured by an OEM and not a knock-off or aftermarket product.
  • Best Bang for the Buck! Very affordable versus other options out there.

Look at this comparative chart to see why the 25AT-350 is superior:

Comparative Chart
It’s all about the horsepower 

To explain the better efficiency and fuel savings resulting by switching from an oil cooled alternator to an air-cooled alternator, consider the horsepower that it takes to turn an alternator:

  • This horsepower is drawn from the vehicle’s engine and the more horsepower that an alternator draws results in more power being drawn from the engine and increased fuel consumption.

The spinning component of an alternator (the rotor), spins in air on an air-cooled alternator. Conversely this rotor spins in oil in an oil-cooled alternator.

Think of trying to run in a swimming pool; the fluid (water) creates resistance, requiring you to expend more energy (fuel) to cover the same distance, than if you were running on the ground.

It takes more than 2 times as much horsepower to turn an oil-cooled alternator as an air-cooled alternator for this very reason.

Easy to replace

The 25AT-350 is a “drop-in” replacement to the oil-cooled 50DN and does not require any modifications to the vehicle.

All key components are the same:

  • Mount.
  • Pulleys used.
  • Regulator.

This unit is “ductless” and does not require any external ducting.


Let us make your conversion smooth and seamless

If you are doing a conversion and require a kit to cap the oil lines that were used for the 50DN, Elreg Distributors can provide you with part #PX-8645.

Many fleets are making the change from oil-cooled to air-cooled alternators as environmental restrictions become more stringent.

It eliminates the potential for a bus to be pulled over and fined for a violation due to oils leaking from the alternator.

Also, as newer and more efficient engines are running hotter, the concept of an oil-cooled alternator really doesn’t work anymore.

Even more reason to contact Elreg Distributors today and change your oil-cooled alternator fleet over to the Almott air-cooled 25AT-350.