Our RV came with a single 12v deep cycle battery, the type that you would buy at a local store like Walmart. This single battery is just fine if you plan on being plugged in when you camp, but for off grid camping or boondocking, it will fall short. To compliment our 1280 watts of solar on the roof of the RV, this was a must do upgrade. While we will definitely be on hook ups from time to time, we will also be out in the middle of nowhere where hookups are not an option, hopefully most of the time.
I had to decide what batteries I was going to upgrade to. After lots of research, I selected the Trojan T-145 6v battery. It is a true deep cycle with 260 amp hours (ah). Although my final plan calls for a total of 8 batteries, I am starting with four, both for cost and simplicity. Once wired in series and then parallel, this will give me 520 ah with 260 ah usable at 12v.
Since 4 batteries would not fit in the stock location, I had to get a battery box. I needed it to be durable and stackable, so my additional 4 batteries could be stacked on these to save space. After a lot of research, I went with a Century Plastics box which I bought from here (best price by far, even with shipping). It is extremely strong, comes with holes for cables, and is rated for being stackable. My four Trojan T-145s fit perfectly in it.
To connect the batteries, I wired each pair in series, then each of those pairs together in parallel. Since each battery is 6v and 260 ah, this gives me a total of 520 ah at 12v. I used the thickest wire I could get, 4/0 ordered off ebay with studs already on both ends. You can order any length you need. This wire is massive and not too expensive. Don’t go small here as this is critical, especially if you are going to be pulling larger loads from the battery bank.
From there, it’s just a matter of installing the box as close to all your other electronics, such as an inverter, solar charger, and so on. Since I use lead acid batteries, I have to vent my box. This is very simple. Find a large diameter flexible hose of your liking from a place like Home Depot or Lowes. Then drill a size and drill a hole in the box so the hose is a nice tight and snug fit. Then just route the hose to the outside. Since you will be venting hydrogen, which is lighter than air, the hose should be on a constant rise to an exit point higher than the battery box. Then connect the batteries to the existing RV wiring (more pics coming soon) and you’re done.