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<blockquote data-quote="Thnking" data-source="post: 2329128" data-attributes="member: 571105">In terms of discharge:Reserve capacity is the number of minutes that a battery can support a 25 ampere load at 80°F until its terminal voltage drops to 1.75 volts per cell, it’s not very useful for a car audio application.&nbsp; It’s probably the least important.The Ah rating is more important, because with a properly sized alternator, there will only be leakage and pulse loads.&nbsp; The Ah tell you the capacity of the battery for a specific time with a specific discharge rate.&nbsp; These are long discharge times, typically something like 10hours or 8 hours with X amps.&nbsp; It also important for determining capacity when many batteries are hooked up to support a load.The CCA is kind of important to competitors (as a vague guideline due to temps), because it tells us the number of amperes a battery can support for 30 seconds at a temperature of 0°F until the battery voltage drops to 1.20 volts per cell.More important than CCA would be HCA (you guessed it Hot Cranking Amps), because it tell us the same info as CCA only at 80°F.&nbsp; MCA (Marine Cranking Amps) is at 32°F.Probably the most important battery spec. to audio and the least defined and used is Pulse Cranking Amps (PCA).&nbsp; Hawker coined this as a shorter than 30sec time period discharge at 77°F until the battery drops to 1.2 volts per cell.When a battery discharge time is decreased, capacity decreases.&nbsp; So a battery with a CCA or HCA rating, when discharged into a small time period like 3 seconds or 1 second, loses much of its capacity.</blockquote>

[QUOTE="Thnking, post: 2329128, member: 571105"] In terms of discharge: Reserve capacity is the number of minutes that a battery can support a 25 ampere load at 80°F until its terminal voltage drops to 1.75 volts per cell, it’s not very useful for a car audio application. It’s probably the least important. The Ah rating is more important, because with a properly sized alternator, there will only be leakage and pulse loads. The Ah tell you the capacity of the battery for a specific time with a specific discharge rate. These are long discharge times, typically something like 10hours or 8 hours with X amps. It also important for determining capacity when many batteries are hooked up to support a load. The CCA is kind of important to competitors (as a vague guideline due to temps), because it tells us the number of amperes a battery can support for 30 seconds at a temperature of 0°F until the battery voltage drops to 1.20 volts per cell. More important than CCA would be HCA (you guessed it Hot Cranking Amps), because it tell us the same info as CCA only at 80°F. MCA (Marine Cranking Amps) is at 32°F. Probably the most important battery spec. to audio and the least defined and used is Pulse Cranking Amps (PCA). Hawker coined this as a shorter than 30sec time period discharge at 77°F until the battery drops to 1.2 volts per cell. When a battery discharge time is decreased, capacity decreases. So a battery with a CCA or HCA rating, when discharged into a small time period like 3 seconds or 1 second, loses much of its capacity. [/QUOTE]

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