When I was deciding what batteries to use for my 5th wheel, the first decision that I had to make was 6 Volt vs. 12 Volt batteries. Based on my research, I found that many avid RVers swore by 6 Volt batteries as being superior to 12 Volt batteries. I know that some people may be a little confused by this as they ask, “Don’t most RVs rely on 12 Volts?” The answer is yes, however, you can use 6 Volt batteries if you wire them properly to output 12 Volts. So the next question that many people ask is, “Why would you use 6 Volt batteries instead of 12 Volt batteries? Why not just use 12 Volt batteries?” If you do some research on the web, you will find endless debates surrounding this topic. In reality, the most important thing to consider is the total Amp Hours you will receive from the batteries in relation to what you can fit into your RV in terms of weight and space. However, there may be some truth to the idea that 6 Volt batteries are superior.
If for instance you use two Group 27 12-Volt batteries that are rated at 105 amp hours each and you wire them in parallel (we will discuss parallel vs. series wiring below), then you will receive a total of 210 amp hours out of your batteries. However, if you use two 6-Volt batteries that are roughly the same size and weight that are rated at 210 amp hours each and you wire them in series for 12 Volts, you will also receive 210 amp hours out of them. So in both situations you are using two batteries and in both situations you are getting roughly the same amount of Amp Hours. So the question still remains why choose the 6 Volt batteries over the 12 Volt? The reason is simple when you consider the batteries construction.
Remember from our discussion earlier that a 12 Volt battery is actually made up of six individual battery cells that each output approximately 2.12-2.15 Volts each. Each one of these cells is made up of a lead plate that is surrounded by an acid solution. Generally speaking, the heavier these plates are, the longer they will last and the better suited they are for deep cycle discharges and recharges. Since 6 Volt batteries only contain three cells per battery as opposed to six cells for a 12 Volt battery and since comparable batteries (in terms of amp hours) are roughly the same size (dimensions and weight will vary), the 6 Volt battery is usually constructed with larger plates and therefore tends to last longer in deep discharge situations. Similarly, you may even find that 6 Volt batteries are slightly cheaper than 12 Volt batteries. As a result of the 6 Volt batteries being constructed better and being slightly cheaper, most avid RVers will choose the 6 Volt batteries if they have the space to mount them. If you do some additional research on the web, you can even find people that have tested 12 Volt and 6 Volt batteries side by side. In all of these tests, the results seem to confirm that 6 Volt batteries are superior.