Battery Groups 101
There are 3 main group of batteries, Starting, Hybrid/Marine and Deep Cycle.
Starting Batteries are found in cars and trucks and will have Cranking Amps (CA) and Cold Cranking Amps (CCA) rating on it. A car engine will require 500-800 CA to start it and this battery is designed to deliver high current for a short time. If you discharge a Starting battery to 10.5v 2-4 times you will damage it and it may no longer start your car.
The Marine battery was developed for boats and will have a CA/CCA rating along with Reserve Capacity (RC) rating on it. The RC is a calculated number and doesn’t seem to have a purpose in the boondocking world. Sometimes they will have an Amp Hour – AH rating and this is the only rating that matters unless you have a generator with electric start.
Deep Cycle Batteries
The Deep Cycle battery will always have an AH rating on it, this rating is similar a gallon measurement of capacity of a gas tank. A typical Golf Cart (GC) battery will have 220AH at 6volts or 110AH at 12volts and weighs about 65 pounds. One 110AH battery will power all of the lights of my ATC RV (10 amps draw on the battery) for 5.5 hours and leave my battery at 50%. This chart shows you typical voltages in relation to State of Charge (SOC). The lower the SOC, the shorter the cycle life expectancy will be for any given battery. Not all Deep Cycle batteries are created equal! The automotive group sizes 24,27,31 and so on are made of less lead and will not give you the same cycle life as GC and industrial batteries. In my opinion, GC/Floor Scrubber batteries are the only type of batteries for boondocking.