To understand the origins of the term “Cranking Amps,” it is important to delve into the history of the traditional automobile engine. Before the advent of electric starter systems, manual cranking was the primary engine starting method. This process was labor intensive and posed a significant risk to the person cranking the engine.
In 1912, Cadillac revolutionized the automotive industry by adopting electric engine starters on all its models. This innovative system utilized a battery to start the engine, providing enough power and current (called “starting current”) to start the engine without manually starting it. By 1920, other automakers had followed suit, paving the way for the rise of the automotive battery industry.
At first, the current required to start the engine efficiently and the effect of temperature on battery performance and the starting mechanism were poorly understood. But it soon became clear that starting batteries had to be able to deliver large amounts of current quickly – about 30 seconds of high-current discharge – and that temperature had a significant effect on the available current (starting current). Low temperatures can significantly affect the engine and its lubricants, as the oil’s viscosity increases at low temperatures, making the engine starting process more difficult.
Recognizing these temperature effects is critical because engines and other vehicle components behave differently at low temperatures. Sealed lead acid (SLA) batteries also experience performance changes at low temperatures. An increase in electrolyte viscosity raises impedance and limits the amount of current that can be delivered. In addition, battery voltage decreases in cold weather, resulting in less available energy. As a result, trying to start a vehicle during a cold Michigan winter may require multiple attempts to be successful.
Cold Start Current Temperature Graph
The current in cold conditions (typically below 32°F and often tested at lower temperatures) is called a “cold cranking current” (CCA). It is typically lower than the standard starting current (CA) measured at temperatures above freezing. In traditional SLA starting batteries, you will see CA (starting current) and CCA (cold cranking current) ratings to reflect this difference.
Because temperature affects both batteries and engines, global standards have been developed to ensure optimal performance in various climates. Organizations such as SAE, JIS, and DIN have developed standards for CCA and CA for automobiles (cars, trucks, and other heavy-engine vehicles).
Most of these standards involve similar test protocols at temperatures ranging from -15°C to -18°C for 10 to 30 seconds while conforming to specific voltage requirements that the battery must maintain during the test. For example, the SAE J537 American Standard, issued in June 1994, states that a 12-volt SLA battery must be maintained at -18°C for 30 seconds at a current of not less than 7.2 volts.
What is the DIN standard?
The DIN standard originated in Germany and is similar to the SAE standard, also testing at -18°C. However, this test discharges the battery to 6 volts and requires that the voltage remain at 9 volts or more for 30 seconds and that it does not take more than two and a half minutes to reach 6 volts.
What is the JIS standard?
Another common standard is the JIS standard D5301:1999, which tests at -15°C and uses 150A or 300A (depending on battery size) to reach 6 volts in 10 or 30 seconds. While this standard reliably evaluates battery performance, it does not accurately reflect true cold cranking current.
All standards discussed in this article apply only to SLA automotive batteries and do not apply to powersports, lithium automotive, or lithium batteries.
Powersports batteries are an interesting topic, especially considering lithium batteries have no cold start current (CCA) standard. Prioritizing starting current and watt-hours is critical when selecting a LiPo battery for a starter. In the next blog post, we’ll dive into standards for power sports batteries and explore the various CA/CCA aspects associated with lithium batteries.
Stay tuned for part two of our blog, where we’ll explore what CCA means for motorcycle batteries.