Battery ratings explained
There can be some confusion when purchasing a new battery, I hope to clarify some of the terminology used here……
Depending on the application the 2 important ratings are AH (Ampere Hours) and CCA (Cold Cranking Amps.
AH is important to know when you are buying a battery for cycling, i.e.. running a fridge or light in your caravan, motorhome or camper.
And CCA is the important rating for start batteries that are required to start the engine in your car.
Cycling or Deep Cycle batteries
These batteries are available in lead acid, sealed lead acid (SLA), AGM or Amalgamated Glass Matt, Lithium and are designed to be cycled between Full and the minimum cell voltage, which is usually 2.0v or 12Volts for a 12 volt battery. Now I know you can use them below 12 volts but for battery health and longevity consider 12 volts as a minimum.
A Rule of thumb for a battery not on charge is:
12.75v – Full
12.50v – Half
12.25v – Empty
Start Batteries are usually lead acid, Calcium (Still lead acid but with a calcium component in the plates), AGM.
What is AH (Ampere Hours)?
The most common battery rating for cycling batteries is the Amp-Hour rating. This is a unit of measurement for battery capacity, obtained by multiplying a current flow in amperes by the time in hours of discharge. (Example: A battery which delivers 5 amperes for 20 hours delivers 5 amperes times 20 hours, or 100 ampere-hours.) 20 Hours is a standard discharge time that has been adopted by most manufacturers for AH rating.
What is CCA (Cold Cranking Amps)?
The industry recognised standard for defining starting power is Cold Cranking Amps (CCA). The battery’s ability to perform is measured by the amount of current the battery can deliver at -18°C over 30 seconds, while maintaining a voltage equivalent of 1.2 volts per cell or higher.
What is RC (Reserve Capacity)?
The Reserve Capacity (RC) rating represents the number of minutes at 26.7°C (80ºF) a battery can supply a load of 25 amps and maintain a voltage of 1.75 volts or higher per cell (10.5 volts for a 12 volt battery).
Higher rated CCA batteries will last longer and perform better in all vehicles than a lower CCA rated battery.
We sell Century batteries are guaranteed to exceed the CCA rating advertised on the battery, while some other manufacturers only claim to be within 10% of the rated capacity as required by the standard.