Batteries are the heart of the RV

Unless you only have one battery, few people want to spend the money to just completely replace all their batteries at the same time. But just like with a used car, you need to monitor the health of your batteries to keep from losing power while boondocking. At some point before batteries fail, you will want to replace them. Keeping the batteries in separate banks with a switch between them means you can replace the batteries only in the bank that fails saving you money. You can even use 12 volts in one bank and 6 volts in another making the combinations virtually endless.

Replacement
If you add more batteries, you will need space to store them in your battery box. You also have to take into account the added weight of any additional batteries. Don't forget when living the simple life, it is best to minimize your need for power instead of complicating your life with more things that fail. Two 12 volt batteries will supply a reasonable amount of power for boondocking. If one of the 12 volts fail, you can still have power from the other one. When replacing your batteries, select the same type or a slightly larger size. It will be the simplest way without having to make any more changes in your power system.

6 volt batteries
A golf cart style battery only provides 6 volts in about the same size package as a 12 volt. The increased space makes them a better battery but you will need more batteries. Two 6 volt batteries will supply about the same amps but if one 6 volt fails you are left without any power. So consider 6 volt batteries as half a battery and you will need two full batteries in case one fails. This means it takes four 6 volt batteries as a minimum. Most setups don't have enough space for those. If you have space and money, go for the 6 volts. If you have a monstrous RV, you aren't living the simple life anyway.

Things you need to know
Your system should include two 12 volts, four 6 volts, or possibly for the adventurous, two 6 volts and a 12 volt separated into two banks with a switch. There are a few rules to follow when wiring up batteries so you need to learn them or let someone else do it. Remember equal cable lengths, and don't wire house power to both terminals on one battery. It needs to be separated across the bank of batteries. See the diagrams. It is best to take a fuel efficient generator along with you.