Alternators: How Many Amps Do You Really Need?

Written May, 2023

The History Behind Alternators

The first alternator, referred to as an electric dynamo, was invented by Frenchman Hippolyte Pixxi. The brothers Perry and Frank Remy entered the technical scene in 1895 when they purchased a 14’ x 20’ shack in Anderson, Indiana, to start their own experiments and build their own alternators.

In only a few short years, they introduced their own manufactured dynamo. In just over thirty years, the Remy brothers’ company expanded from a two-man operation. It grew to 10,000+ employees under the company we now know today as “Delco Remy”. During this time, the Remy brothers continued to invest in the improvement of the electric dynamo.

Modern automotive alternators were introduced into vehicles in the 1960's. This was due to the rapidly evolving need to provide electricity for lights, horns, radios, and other equipment. To meet those needs, an increase in battery voltage from 6V to 14V was made. Delco Remy has continued to remain an important contributor to these advances.

Fast Forward: Choosing the Right Amperage

Choosing the right amperage for your heavy duty application is imperative to protecting the life of essential electrical components, such as your alternator, battery, and electrical systems. Whether you're a truck owner, fleet manager, or mechanic, choosing the right heavy-duty truck alternator is crucial for maintaining optimal performance and minimizing downtime.

With over 125 years of experience, Delco Remy is committed to ensuring your uptime stays up.

Alternators operate most efficiently when using 50%-60% of their rated output. Remember, more amperage is better than less when it comes to the right alternator. Insufficient amperage can lead to underperformance, electrical system failures, and a drained battery. It's also important to know that the number of amps you need is heavily dependent on your unique operation. Here are a few questions you may want to consider when answering, “How many amps do I really need?” :

• How many starts & stops do you perform each day?
• Are you using heavy duty equipment like a lift gate that can drain your charging system?
• Do you use an Anti-Idle System?

If your answer is “yes” to any of these questions, you may need a higher output alternator. The Delco Remy 28SI™ series offers a range of outputs from 160 to 200 amps. Alternatively, an upgraded Delco Remy 40SI™ series may be suitable. With the 40SI™ series of high output alternators, you get not only outputs ranging from 240 to 320 amps, but the added durability of its brushless design. Made with 13 fewer moving parts, experience enhanced service life and performance with the top output at idle in the industry - as high as 190 amps (depending on the model).

If you're planning to operate your truck for three or more years, investing in either the Delco Remy 36SI™ or 40SI™ brushless alternators, the most efficient alternators available in class, will deliver less wear for longer life. Don't just take our word for it; ask the top 100 national fleets, of whom 90% choose Delco Remy brushless alternators. Delco Remy's brushless alternators provide low operating costs with the durability fleets needs.

Delco Remy: Superior Performance

Delco Remy alternators are known for operating with superior efficiency that provides measurable fuel savings, remote sense technology that reduces battery charge time and helps to prevent warranty claim, and brushless designs that provides the highest in class durability. With decades of experience in the industry, Delco Remy alternators are engineered to withstand the demanding conditions of commercial vehicles. With our extensive All-Makes product offering, Delco Remy partners with FleetPride to ensure you stay Ready for the Road Ahead™.

* The forgoing is provided for informational purposes only. Please consult your local FleetPride Heavy Duty Experts to verify the suitability of a part for the intended application.