A basic camping RV does just fine at 12 volts. All of things that run on the 12 volts are designed to. The light bulbs. That small fan. Some small fridges. The water pump. When you are not plugged in, you are running these things off the batteries. Depending how big the batteries are dictates how long you can go between recharging them.
Your Inverter takes those 12 volts and ups them to 110 volts so you can use your coffee maker, hair dryer, xbox, and all the other crap that runs off 110 volts. Take a minute here. Stop. That means you have about 10% of the juice available that the wall plug in your home does. TEN percent. This is important to understand that batteries valiantly try to keep up with the demand most people want them to. In order to do that, you HAVE to treat that battery or batteries right.
Your RV also has a converter / charger. It does the opposite of the Inverter. It takes the 110 volts from your house or shore power, and knocks it down to around 14 volts to charge the batteries. Batteries are called 12 volts but they are really fully charged at 12.7 volts. The only way to charge a battery is give it higher voltage than it has. So most converter chargers deliver around 14.5 volts. And usually only in one stage. See the previous blog to understand the 3 stages of charging.
So unless your converter charger is 3 stage and high end, it will never really charge your batteries the right way. They work, but not as good as they could. A Trojan T-105 can go 12 years charged properly, or 4 years off a basic converter charger.
Another problem is the cheaper converter chargers never really know when to shut off. They just blast the battery with juice in bulk stage. And at how many amps they do so, is all over the map. So if you took a single 12 volt deep cycle battery out, and put two 6 volt T-105's in, already the converter charger may not have enough amps to properly charge the two batteries.
So while it is a process, if you take care of your batteries with a good charger that is stand alone from the RV, (if it has a cheap converter charger ) you will get years more out of your batteries.
Making sense? Batteries LIKE to be used, and like to charged harder than you might think. More batteries are murdered from undercharging than overcharging every day of the week.
Some people have asked us what about going to 24 volts? For off grid? There is a distinct advantage to this. When the electrical current is increased from 12 volts to 24 volts the thickness of all the wires in the system required drops dramatically. This is because of heat.
The less flow at 12 volts ( think of it as a narrow river ) causes heat build up. If you double the width of that river (24 volts) there is much less heat. Therefore you will save big money on the cabling over distances for how thick it is. The power to your house comes to your street at giant voltages, then drops way down to enter your house. This is because BC Hydro can send that energy with much thinner wires at those huge voltages than if they sent it at 110 volts.
Another advantage is that if you are using solar for example, the amperage rating max load on the controller for 12 volts get so high with a lot of batteries, that they are almost not even made. Switching to 24 volts allows the amp load for the controller to be much less and are readily available.
If you are at all serious about a small cabin off grid, then 24 or 48 volt systems are the only way to go.
Bonus information - A 110 volt dryer at home compared to a 220 volt dryer actually do the same thing. The difference is because the motor on a 220 volt needs SO much less and thinner wire than a 110 volt does to handle the heat, it is much less money to manufacture the 220 volt dryer.
Same principle applies to batteries. Higher volts = less heat = thinner wires = less money.