An RV battery is a collection of lead-acid cells... which is why they are called batteries in the first place. Each cell, when fully charged, will produce close to 2.5 volts. It takes 6 cells connected in series... negative to positive... to make a 12 volt battery which when fully charge will produce approximately 12.6 volts. Of course it only takes three cells to make a 6 volt battery that, when full charged, will produce about 6.3 volts.

It doesn't matter how big the lead-acid cells are they will still only produce 2.5 volts. You can see this for yourself if you compare a standard RV/marine 12 volt battery to a standard 6 volt golf car battery. The two batteries are ruffly the same size and weight but the 12 volt battery has 6 cells while the 6 volt battery three. We can assume the cells in the 6 volt batter are larger and contain more lead than the cells in the 12 volt battery.

The larger cells in the 6 volt battery allow it to provide electricity longer while maintaining a usable voltage and that is partly why many RVers choose to use them. Since RV circuits operate on 12 volts, an RVer who chooses to use golf car batteries will need two of them connected in series... 6 cells x 2.5 volts = 12.6 volts... just as the individual cells are connected in series.

It's important to note that while connecting two 6 volt batteries in series will double the voltage it does not increase the amount of time the batteries will provide usable power. That is determined by the size (amount of lead) of each cell.

A parallel arrangement connects all the positive sides of each battery together and all the negative sides of each battery together. When connecting two 12 volt batteries in parallel, the voltage stays the same but the battery bank will provide electricity longer while maintaining a usable voltage.

The critical difference is that series batteries add voltages together at a common current while parallel batteries add currents together at a common voltage. This is important because lead acid battery energy capacity is significantly influenced by the current drawn from them and not by their voltage.

You may want to read these articles on RV Batteries:

• RV Electrical System Basics
• RV Battery Use, Care & Maintenance
• RV Battery Power Management
• RV Batteries - How long will a charge last?
• RV Batteries - What's draining my battery?
• Absorbed Glass Mat Battery - Pros & Cons
• Troubleshooting a 12-volt DC Problem