In my last post about solar power, I completely ignored one essential part of any functioning solar installation: Batteries to store energy for when the sun is not shining.
All RVs have at least one house battery so that it is possible to use it without plugging in. This battery will be just fine for running a few lights and the water pump, but for anyone planning to stay longer than a night or two at a time without hookups, it will probably not be enough.
Our travel trailer came with a standard dual-purpose 12v marine battery.
This battery came installed in our trailer.
This type of battery is a compromise, it is designed to function as a starter and as a deep cycle battery. Like so often with this type of compromise it just means it isn't very good at either function. I discovered just how bad our battery was the first night we slept in it without hookups.
We wanted to stay close to my inlaws and there is, unfortunately, no way to get a trailer this size up their driveway so we had asked a church just down the block from them if we could stay in their parking lot for the night. This was in the late fall which meant we needed to run our heat. The battery was freshly charged but I discovered at about 4 in the morning that it no longer had enough power to run the fan for our forced air heating. It was getting very cold in the rig! The only thing I could do was to hook up to the car and run the car to charge the battery. This allowed us to run the heat and bring the temperature up again. I think I ran the car for almost 40 minutes before going back to bed. At 7 the battery was empty and it was very cold so I had to run the car again. I knew that this would not work and that I would have to get a new battery.
I did some research and decided that instead of one 12v battery it would be better for us to get two 6v true deep cycle golf cart batteries. Cost, as always, was a major concern and I settled on getting 2 Duracell 6v 225AH golf cart batteries. This would more than double our amp hours of battery power. It would also allow us to use more of the power without damaging the batteries, as with this type of battery you can use about 50% of the power without any damage. I know that there are other types of batteries that are even better, lithium-Ion for example, but they cost much more.
To house and protect the new investment I also got a quality battery box and mounted it where the old battery was.
I had to modify the battery tray to fit the new box.
The new box before I put the batteries in.
We have now had these two batteries installed and working for a little more than one year. I don't worry about using the heater overnight if needed. With the 100w solar panel deployed we have boondocked for as long as a full week without any problem, although this was in southern Florida and heat was not needed at all.
Right now I'm writing this parked without hookups on BLM-land in southern Arizona, the heater just kicked in for the first time of the night, and I know that we will have all the power we need. Outside in the dark, the solar panel is ready for sunrise in about 10 hours.
Thanks for following the journey of me and my family
as we travel and roadschool our kids around the USA.
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