Battery Equivalents and Replacements

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

optima 34 78 redtop w150px
optima 34 78 redtop w150px

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 the battery usage.

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.

car battery amps m
car battery amps m

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:

BCI Battery Group Starting / Cranking Dual Purpose Deep Cycle
Group 8D - 220 Ah, 1450 CCA 250 Ah, -
Group 24 - 76 Ah, 840 CCA 85 Ah, -
Group 31 - 100 Ah, 1000 CCA 120 Ah, -
Group 34/78 50 Ah, 800 CCA 65 Ah, 850 CCA -
Group 35 44 Ah, 720 CCA 60 Ah, 740 CCA -
Group 47 (H5, L2, 55L2) 60 Ah, 600 CCA 50 Ah, - -
Group 48 (H6, L3, 66L3) 70 Ah, 760 CCA 70 Ah, 750 CCA -
Group 49 (H8, L5, 88L5) 92 Ah, 850 CCA 90 Ah, 850 CCA -
Group 51 (51R) - 60 Ah, 700 CCA 60 Ah, -
Group 65 - 75 Ah, 850 CCA -
Group 75 55 Ah, 760 CCA 55 Ah, 750 CCA -
Group 94R - 80 Ah, 800 CCA -
Group YTX20L-BS 18 Ah, 270 CCA - -
Group YTX24HL-BS 21 Ah, 330 CCA - -
Group YTX30L-BS 30 Ah, 385 CCA - -

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 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 the 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.

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