batteries

One thing that is very important to consider when connecting two batteries together is they MUST be as close as possible date wise! The optimum would be to have 2 batteries with consecutive serial numbers. The reason is thw weaker of the two will bring down the stronger one, never the other way around! If you currently have an existing 12 volt that is a couple of years old, adding a new 12 volt in series will be a waste of your money, as the new one will fail prematurely! If you need to add batteries for dry camping or adding capacity, please buy two new ones and check both manufacture date as well as the serial numbers and get them as close as possible! Good luck!