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Myth: Cold Cranking Amps

Mazourka Battery Rack

In one sense, Cold Cranking Amps are real. The number of amps that are produced by a charged battery during a 30-second period while maintaining at least 7.2 volts at a temperature of 0°F. In application though, there has been a problem with store presenting this as the only spec that matters. Recently, when setting up for Special Olympics we had a battery failure on one of the trailers. I went over to a local auto parts store where a sales person intercepted me on the way to the battery rack. The first thing he asks is what model car, so I have to tell him it is not a car. Not to be discouraged he starts telling me the Cold Cranking Amps on various batteries. At this point I need to remind him multiple times that there is no engine so Cold Cranking Amps is irrelevant and I ask him for the Amp Hour ratings. An Amp Hour rating is the number of hours that 1 amp could be drawn off the battery. This is the spec we use when calculating standby power applications such as DAS systems or Radio Sites. This number can be used to calculate the battery run time for various applications. For instance a 100 amp hour battery feeding a piece of equipment that draws 5 amps will last 20 hours. This is the scenario that applies to the power requirements of the trailer, or the secondary battery (for the radios) in my truck since cranking an engine in cold weather is not what they do. This sales person continued to push CCA and would not attempt to look for the AH ratings. I selected and bought a battery over his objections and it did the job for me.

In a similar incident, I encountered a woman whose car wouldn’t start at night. I stopped to assist her by performing diagnostics. It was evident that the battery voltage was initially low and decreased further when a load, such as the headlights, was applied. Clearly, the battery was not fully charged. I successfully jump-started the car, which indicated that the charging system was functioning. Therefore, I concluded that she needed a new battery and advised her to contact the Auto Club for assistance. When the driver arrived, I shared my observations with him. He proceeded to lecture me, using an automated battery tester, about how “voltage doesn’t matter.” He argued that as long as the battery had the necessary Cold Cranking Amps, it could be at 0 volts. However, this statement contradicted the definition of CCA. Anyone familiar with physics understands that without voltage, there is no current (amps). According to the formula Volts/Resistance=Amps, having 0 volts would result in 0 amps.

Understanding the relationship between the starting current of an engine and the Cold Cranking Amps (CCA) is essential when selecting a suitable battery for cold weather conditions. However, it’s important to note that the relevance of CCA diminishes in warmer temperatures and becomes completely irrelevant when the focus shifts to applications requiring runtime rather than starting current. In such cases, Amp Hours (AH) are the key parameter, or alternatively, Watt Hours (WH) can be used and converted as necessary. The formula AH*Volts=WH can be applied for this purpose. In general, a battery with a higher CCA rating will also have a larger AH rating. However, it’s crucial to understand that there is no direct correlation or conversion between these two specifications. It’s a common misconception that the runtime calculations can be derived from the CCA specification. Unfortunately, this misconception has led to a significant number of individuals in the automotive industry being trained incorrectly and lacking a comprehensive understanding of these principles. To further emphasize the importance of this knowledge, let’s delve into the practical implications. Picture yourself in the depths of winter, standing in front of your vehicle, eagerly trying to start the engine. The chilling wind pierces your skin, and you’re desperate for the engine to roar to life. This is where the starting current and CCA come into play. With the starting current in mind, you can make an informed decision about which battery will provide sufficient power to start your engine even in the coldest temperatures. Now, let’s consider a different scenario. Imagine you’re planning a camping trip, and your primary concern is not starting the engine in cold weather, but rather ensuring a reliable power source for your appliances and devices throughout the trip. In this case, the focus shifts to runtime, and the Amp Hours become the crucial factor to consider when selecting a battery. By understanding the AH rating, you can ensure that your battery has the capacity to power your devices for an extended period. To illustrate the significance of AH and WH even further, let’s explore an example. Imagine you have a battery with a capacity of 100 Amp Hours and a voltage of 12 volts. By applying the formula AH*Volts=WH, you can determine that the Watt Hours of this battery would be 1200. This information is invaluable when planning your power consumption and understanding how long your battery will last before needing to be recharged or replaced. However, it is disheartening to acknowledge that despite the importance of these specifications, there is a prevalent lack of understanding within the automotive industry. Many individuals have been trained incorrectly, leading to misconceptions and misinformation being perpetuated. This highlights the need for accurate education and awareness regarding the principles of CCA, AH, and WH. With the correct knowledge, both consumers and professionals in the automotive industry can make informed decisions and ensure optimal performance and longevity of batteries in various applications.

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