The most common term for describing the amount of power a starting battery will deliver is CCA or cold cranking amp. This is a measurement of how much power the battery will deliver for 15 seconds at -17.8C. They are several other different cranking amp and hot cranking amp ratings, and the difference is the temperature at which they are rated, these are always higher than CCA.
Another measurement of capacity a battery will deliver is amp hour rating. Amp hour is a measurement of how much power the battery will deliver over a set period of time. This is common in standby emergency lighting batteries, AGM batteries, and we're starting to see some starting batteries rated an amp hour now as they do commonly in European products. Amp hour is typically a measurement over a 20-hour period of time. So, as an example, if a battery is rated at 100 amp hour that means it will deliver a continuous 5 amp for 20 hours. There are several different ratings when it comes to amp hours as far as the period of time and those are generally for forklift batteries that can either be rated at a 6-hour rate and other UPS and renewable types that are rated at sometimes 8-, 10-, and 100-hour rate. But the common terminology or the common rate that we use is a 20-hour rate per amp hour.
Reserve capacity is another common number we use for measuring the amount of amps delivered over a period of time. This is a common measurement for staring batteries and RV deep cycle batteries. As an example, if an RV battery is rated at 150 minutes reserve capacity, that means that that battery will deliver a continuous 25-amp draw for 150 minutes until the battery is considered discharged. Again, like the other ratings, there are different amperage discharge ratings. So in heavier golf cart and deep cycle type batteries, they may be rated at a 56-amp draw or a 75-amp draw to represent electric vehicles that are drawing more amperage. But the common amperage draw that we use that we're talking about and referring to when we're talking about reserve capacity is a 25-amp draw.
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