Multiple RV Batteries
Connecting Multiple RV Batteries
When installing more than one battery for use with the 12 volt RV system, it is recommended to purchase the
batteries at the same time. The batteries should be matched with regard to capacity, brand, and age. This will give
you the best possible life from your RV battery bank.RV Battery Voltages
RV Batteries are constructed to supply 12 volts or 6 volts (for the purpose of this article). In most cases two
six volt batteries will have about 20% more capacity than two similar sized 12 volt batteries. This is due to the
larger plates that are built into a six volt battery.
RV Battery Circuits
Two 12 volt batteries are connected in a parallel configuration with the two positive terminals
connected together and to the positive trailer lead. The negative terminals are connected together with the
trailer negative lead.
Two six volt batteries need to be connected in a series circuit in order to get the 12 volt
needed to run the coach system. In this case the trailer positive lead is connected to the positive terminal
of the first battery. The negative terminal of that battery is connected to the positive terminal of the
second battery. Finally, the negative terminal of the second battery is connected to the trailer negative
lead. The size of the jumper wire should match or exceed the size of the trailer leads.
RV Battery Polarity
It should be noted that the positive lead from the trailer is normally the black colored wire(s) while the
negative lead is the white colored wire(s). This is sometimes confusing, as most automotive applications use red as
the positive and black as the negative. Polarity is very important to the electronics and the various motors in the
RV and must not be reversed.
Note: battery terminals (or posts) are marked with a plus sign for the positive terminal and a minus sign for
the negative terminal.
To make it even more confusing, makers of after market items, such as solar panels will have the red wire as
positive and black as the negative.
Before disconnecting your RV battery for any reason, it is suggested that you tape the wires together near the
terminal that they are attached to and then mark them with respect to what terminal they go to. This will avoid
confusion and reversed leads when re-connecting the terminals.
Hard to reach your batteries?
Qwik-Fill™ 12-Volt Battery Watering System with Filler
Remote battery watering systems lets you fill all batteries to proper electrolyte levels from a single
fill tube, using a simple hand pump. Safer and more accurate than conventional filling.