Power is everything when you are RVing off grid. Solar and generators are awesome for generating power but in the end you still need the good ole battery in which to store that generated power. Batteries these days come in a variety of different types, styles, and voltages, but for RV’s the most common battery used is the flooded cell deep cycle battery.
The flooded cell battery has been around for a very long time and is the most common battery used in RV’s and or vehicles. This type of battery lends itself very well to storing power at a reasonable price. These batteries come in two type’s standard or deep cycle and they come in two voltages 6 volt or 12 volt. For the RV’er the best battery around is the deep cycle 6 volt battery.
Now a lot of RV’s will come with the 12 volt variety, and this is typically found in travel trailers and fifth wheels, and while good, these batteries tend not to last as long as the deep cycle 6 volt, and their interior plates are typically not as thick and robust as the 6 volt variety. This really comes into play when deep cycling the battery. What is deep cycling? It is when you discharge a battery below its mean voltage. For example if you discharge a 12 volt battery below 12 volts you have deep cycled that battery. Now deep cycle batteries are designed to do this but every time you do you shorten the life of the battery, and if you do this enough times the battery will no longer charge and it will need to be replaced.
Now I have used both 12 volt and recently 6 volt batteries in my new RV. The 12 volt batteries worked well and in our old RV, and I had three of them for a total power load of 12 volts with 600 amp hours of reserve. What is amp hours? That is the time that it will take for a battery to discharge while under 1 amp of load. This is important to know as you assess how much power your rig needs to run all of its systems while off grid. This is really important to know but it will require another article to fully explain.
The 12 volts batteries I used in my old RV as I said worked well for what I used them for, which was running all of the systems of the RV, but over time I found that they did not hold up very well and failed more frequently than I would have liked. I also found that they tended to discharge quicker than the new 6 volt batteries I have in our new RV. Most 12 volt batteries will only last a few years, maybe four if you look after them. Whereas the 6 volt battery has much thicker plates, they can store power longer and have a high resistance to sulfating. These qualities make the 6 volt the better option for an RV battery bank and may see them last longer.
So if 6 volt is better how do you get 12 volt out of them? Well you connect two 6 volt batteries in series, this will then combine the voltage to 12 volts, but keep the amp hours the same as if you had only one battery. So a 6 volt that has 230 amp hours when connected in series to an identical battery will then produce 12 volts with 230 amp hours of discharge time. If you require more power and who doesn’t then you will need to connect more 6 volt batteries.
In my new RV I have four 6 volt batteries in two banks. So two batteries per battery bank. Each of these banks is connected in series to its twin battery, and then the two banks are then connected in parallel in order to combine the banks. This keeps the voltage at 12 volts and increases the amp hours of discharge by double the original amount.
For example if I have four 6 volt batteries each with 230 amp hours by combining them as described above I now get 12 volts with 460 amp hours of discharge. In the end this is a much better setup than using multiple 12 volt batteries in parallel.
I have found that over the year that we have owned the new RV the 6 volt battery bank lasts longer and powers my inverter better than the old 12 volt batteries. I also find that I am not deep cycling my batteries in between charges, whereas with my old 12 volt system I was always in a deep cycle mode prior to recharging.
Lastly we should discuss types of batteries. We already know about the flooded cell batteries that will require regular maintenance (Adding Water to the cells) in order to keep them in tip top shape, but there is another option that is maintenance free. Welcome to the AGM battery. These batteries are sealed and require no maintenance other than charging. These batteries utilize a glass mat plate that is highly resistant to sulfating, which in turn allows the battery to provide a more steady power discharge and deeper deep cycle. Now AGM’s are great if you want maintenance free, but there is a drawback. The batteries don’t provide a higher spike discharge when compared to flooded cells. For most of us this is not a big issue, but if you use your batteries to provide power to start big ticket items like A/C or multiple devices all at once then these batteries may not be able to keep up with the demand. Another issue with these batteries is charging. These batteries require a higher charge cycle than flooded batteries and therefore your standard charger may not be capable of properly charging these batteries and a new charger would be needed to implement AGM’s.
Other batteries that are available are Gel and lithium. Now Gel batteries use a gel medium between lead plates to provide the charge. These batteries are similar to AGM in function and also require a special charger in which to charge the batteries. Lithium batteries are still really new and very expensive, though we are starting to see them utilized in newer RV’s. When it comes to solar power storage the best batteries to use are still flooded cell or Lithium.
In the end batteries are at the heart of any RV’s power system. The bigger the RV the more batteries will be in your bank. For the average Class “C” you will find that they come stock with two 6 volt batteries. It is very easy to add two more batteries, (if you have the space for another bank) that will double your amp hours of discharge, so that you can run your RV’s electrical system without having to worry if you will have enough power to last the night.
Over the years of RVing I have tried both systems, 12 volt and 6 volt, and I can honestly say I prefer the flooded cell 6 volt variety. These batteries provide the best bang for your buck and perform exceptionally well in a RV environment. Since power is the heart and soul of an RV, you will get more bang for your buck to use flooded cell 6 volt batteries over any other battery variety. Flooded cell technology still provides the best power storage and discharge rates and at a reasonable price so that you’re RV will always have power when you need it.