How to Convert Cold Cranking Amps (CCA) to Amp Hours (Ah)

Conversion between Cold Cranking Amps (CCA) and Amp Hours (Ah) is not a direct one for one very simple reason: Cold Cranking Amps describe the ability of the battery to provide strong currents required for starting/cranking of internal combustion engines, usually for 30 seconds, while Amp Hours (Ah) describes the capacity of the battery and its ability to provide certain current for, usually, 20 hours.

Basically, Cold Cranking Amps (CCA) and Amp Hours (Ah) both describe the capacity of the battery and its ability to provide current for some time - they are just two extremes of battery usage.

Updated: November 28, 2022.

Cold Cranking Amps (CCA) vs. Amp Hours (Ah)

CCA (Cold Cranking Amps) is the value (given in Amps) of the maximum current that a new, fully charged, 12V battery can deliver for 30 seconds, with the voltage NOT dropping below 7.2V, at 0°F (-18°C).

Of course, there are several definitions of the CCA value, standard dependent, but this is the most common one.

Capacity is the value that directly describes the capacity of the battery and is given in Amp Hours (Ah).

The capacity of the new, fully charged 12V lead-acid battery is the value of the constant discharge current delivered for 20 hours without the battery's voltage falling below 10.5V, at 80°F (~27°C), multiplied by 20h.

For example, a lead-acid battery that is able to provide 5 Amps for 20 hours has a capacity of 100 Ah.

The capacity of the lithium and other similar batteries is the value of the constant discharge current delivered for usually 20 hours without the battery's voltage falling below cut-off voltage, multiplied by, usually, 20h.

Obviously, when dealing with lithium batteries, it is very important to check the actual values - some manufacturers provide 1h capacity, some 5h capacity, some 10h capacity, etc.

When trying to convert Cold Cranking Amps (CCA) to Amp Hours (Ah), the main problem is that this conversion depends on the battery model, chemistry, intended use, and similar - it is important to note that there are starting, dual-purpose, and deep cycle types of batteries, each designed somewhat differently from the other.

Starting batteries are the most popular type of car batteries and are used for cranking the engine and for powering various lighter loads (lights, audio, security system, and similar) while the engine is turned off.

However, starting batteries should not be used for deep cycle applications since their plates are relatively thin with a large surface, optimized for high current applications.

Dual-purpose batteries are unable to provide as strong cranking currents as starting batteries, but they tolerate much better deep-cycle use. Dual-purpose batteries are used as both cranking batteries and for powering various loads while the engine is turned off.

Dual-purpose batteries are very common industrial and marine batteries, becoming more and more popular even in cars due to the increased power demand during periods when the engine is off.

Deep cycle batteries are optimized for deep discharge and cycle applications - they are unable to provide strong currents, but they cycle well.

Cold Cranking Amps (CCA) to Amp Hours (Ah) Cross Reference Chart

The following cross-reference chart lists average CCA and Ah values for starting, dual-purpose and deep cycle car, RV, marine, and light industrial batteries, depending on their BCI group:

Note: again, these are 'average' values since they can differ significantly between the batteries of the same BCI group - for example, Optima batteries are known for their ability to crank large engines, despite having a relatively lower capacity (and weight!) due to their spiral-wound cells.

On average, CCA to Amp-hours relation depends on the battery type, and on average, it is:

- starting lead-acid batteries: Capacity (Ah) x 10-16 = CCA (Amps)

- dual-purpose lead-acid batteries: Capacity (Ah) x 8-12 = CCA (Amps)

- deep-cycle lead-acid batteries: Capacity (Ah) x 4-8 = CCA (Amps)

Note: many manufacturers limit (at least on paper) the maximum current of their deep-cycle batteries, emphasizing the fact that they are not designed for such use.

In order to check actual capacity and CCA dependency, always check the documentation of the battery and use these values only as orientation values.

Lithium Batteries CCA to Ah Conversion

Most automotive and light industrial lithium batteries are deep-cycle Lithium Iron Phosphate (LiFePO₄) batteries that feature Battery Management Systems (BMSs) which disconnect the battery when the temperatures are low, sometimes already at 32°F (0°C), although most often at 14°F (-10°C).

Also, most lithium batteries have limited currents to 1C continuously and usually 2-3C for 2-5 seconds - for example, a typical LiFePO4 12V 100Ah battery feature a maximum continuous current of 100 Amps and surge current of 200Ah for 2-5 seconds.

Thus, talking about the true CCA value for such batteries makes no sense.

However, for some starting lithium batteries, their manufacturers provide "CCA" values that are actually "MCA" (given for 0°C) or even "PHCA" (given for 25°C) but are still labeled as "CCA" values.

Direct conversion from CCA to Ah and back for lithium batteries is impossible to give since they vary significantly - for example, there are starting lithium batteries for Powersports applications that have their CCA (Amps) in the 100+ range of their nominal capacity given in Amp Hours.

CCA (Amps) = Capacity (Ah) x 100

Such batteries offer great weight savings and improve engine starting/cranking, but they tend to be more expensive than lead-acid batteries.