how to read battery amps

[captainKJ]

I looking at several types of 6 volt batteries. each has about 225 A.H. If I put 2 of these batteries together to make a 12 volt battery do I have a total of 450 A.H. at 12 volt or only 225 A.H. at 12 volt. I am talking the total not the usable amperage

[GordMay]

Batteries, connected in Series, doubles the Voltage (2 @ 6V = 12V), but the A/H Capacity remains the same.
Batteries connected in Parallel, DOUBLES THE CAPACITY (2 @ 220 a/h = 440 a/h); but the Voltage remains the same.

Hence: Your (2) 225 A/Hr, 6 Volt batteries, connected in Series, will produce a 225 A/Hr, 12 Volt bank.