I’ve been a long time fan of 6 volt batteries for my trailer. The amp hours in a pair of 6 volt batteries is about double that of one 12 volt deep cycle battery and with proper maintenance will outlive them as well. My last set of Trojan T-105’s lasted 7 years and were sold with my trailer so for all I know they are still going strong. By comparison, my friends with 12 volt batteries seem to change them out every 3 years.

When it came time to buy new batteries the plan was to buy another set of Trojans, that is until I looked at the price. My local Battery Systems store wanted $145 a piece, ouch! So I did some research and found that a lot of people were having good luck with Costco’s 6 volt batteries. So at $79 a piece I thought I’d give em a try.

After picking up the batteries I went down to my local A1 Battery store in Visalia, Ca. to have some custom length interconnect cables made from 4/0 welding wire and 3/8 lugs.

Next I connected the batteries in series. Now a lot of people get confused when trying to understand how to wire 6 volt batteries to make one big 12 volt battery. Buts its really not that complicated. Take two batteries at a time and connect them together from negative to positive as in the following diagram

Now do the same for the second set. Now you have two big 12 volt batteries. Next, connect the two sets together like you would two 12 volts; negative to negative, positive to positive. Study the following diagram and the light bulb will come on.