I have a 12V 5A CPAP device that I'm looking to use while camping for 2 nights. Therefore, I'm trying to determine a deep cycle battery to meet my needs without burning a hole in my wallet. Based on calculations I've seen while browsing the net, I need a battery that can deliver 200AH. Calculation is based on C'' found here: http://www.powerstream.com/battery-capacity-calculations.htm
However, searching various car batteries at different stores, they are not listed as deep cycle, but rather CCA (Cold-cranking amps). Searching for a 200AH Deep Cycle battery results in batteries that are over $300.
Am I calculating this incorrectly? I was hoping to spend far less considering I won't use the battery very often.