An alternator serves as the heart of a vehicle’s electrical generation, converting mechanical energy into substantial electrical current. While standard alternators suffice for typical applications, high output models like those American Power Systems manufactures are engineered for scenarios where energy needs exceed conventional supply.
This includes emergency vehicles, work trucks, cargo vans, recreational vehicles (RVs), marine applications, luxury motorcoaches, and even security vehicles. All of these often require additional power due to additional weight and specialized onboard electronic equipment.
But with a high output alternator’s enhanced amperage capacity comes an inherent challenge: increased heat production. Managing this heat is fundamental to both performance and longevity, making temperature monitoring essential. However, the effectiveness of temperature monitoring hinges critically on one often overlooked factor: the precise location of the temperature sensor within the alternator.
At APS we place temperature sensors on the inside of the alternator housing in the same location as the OE regulator. This gives the truest reading of temperatures most relevant to the behavior of embedded safety mechanisms.
Why do we say most relevant? Safety mechanisms are designed to trigger alarms or corrective actions such as reducing alternator load, adjusting fan speeds or even shutting down the system if unsafe temperatures are detected. But those triggers must be based on a true temperature reading.
Have you ever driven past a bank marquee on an 80-degree day, but the digital sign tells you it’s 96 degrees? It isn’t that the thermometer is broken; it’s most likely located somewhere – perhaps in a sunbeam – that has external factors influencing its reading.
The same can be true with an alternator temperature sensor: its location can be influenced by additional external factors that yield misleading readings.
For example, heat coming off the engine may build up under the hood, causing a spike in the temperature reading of an externally placed sensor. This high heat reading could trigger the alternator to pull back its load (a de-rating of the alternator). Conversely, exposure to ambient air can report a cooler temperature on the housing and fail to pull back the system until damage to the alternator has already occurred. Either way, readings from an externally placed sensor are far less reliable than an internally placed sensor.
“The significance of an alternator’s temperature sensor’s location cannot be overstated, which is why APS takes great care to position them for the most accurate thermal monitoring in our designs,” said Greg Yerington, APS’ Principal Director of Engineering. “This helps to safeguard against overload and ensure optimal performance under demanding conditions.”
APS uses temperature readings as part of our rigorous engineering and testing process during which an alternator is placed in an enclosure heated to 100°C (212ºF) while the alternator is running. Using this intensive saturated dwell test ensures our products withstand the most severe conditions while meeting the highest quality and safety standards. Having the most accurate sensor placement during this testing helps us to:
While APS sets temperature thresholds for the alternator at certain levels before it leaves our facility, it is critical for the end users to know and understand the environment in which they will use the vehicle in case they need to re-program the factory settings.
As alternator technology advances and electrical demands rise, the careful consideration of sensor location will remain a central factor in the quest for efficiency, durability, and operational safety. Even though there is no “correct” temperature for an alternator to be programmed, it is still very important to read the temperature from the most reliable source.
Ready to learn more? Contact our sales team about your specific vehicle application.
Temperature sensor placement is important because thermal protection systems rely on accurate temperature data to trigger alarms, reduce load, adjust cooling measures, or shut down equipment when necessary. An inaccurate reading can negatively affect performance and equipment protection.
APS places temperature sensors inside the alternator housing in the same location as the OE regulator. This location provides temperature readings that are most relevant to the alternator's safety mechanisms.
External sensors can be influenced by outside factors such as engine heat or ambient airflow. This can result in temperature readings that are either higher or lower than the alternator's actual operating temperature.
Alternator derating is the intentional reduction of alternator output when temperatures reach a level that could threaten safe operation. It is one of the corrective actions that may be triggered by temperature monitoring systems.
A falsely high temperature reading may cause the alternator to reduce output unnecessarily, while a falsely low reading may delay protective actions and increase the risk of alternator damage.
APS places running alternators in an enclosure heated to 100°C (212°F) as part of its saturated dwell testing process. Accurate sensor placement helps ensure meaningful thermal data is collected during testing.
Temperature monitoring helps APS identify durability and reliability improvements, uncover endurance-related design issues before release, and verify long-term performance expectations.
No. While there is no single "correct" programmed temperature for every alternator application. However, obtaining temperature data from the most reliable source remains essential.
