By far the largest volume of technical support I provide to RV owners is related to the electrical system. This is not surprising however, considering the electrical and propane systems basically comprise the entire house system. Many owners struggle with both these areas, but the electrical system remains the most elusive. Over the next few weeks, I will be discussing the RV electrical system.
Although the propane system is currently central to a recreational vehicle, manufacturers are moving towards electric appliances, which is resulting in less reliance on propane and more on electricity, making the electrical system truly the “heart and soul” of the RV.
The electrical system is complicated by the fact that there are really two sub-systems involved; the 12V DC and 120V AC components. Although this confuses some consumers, it’s relatively straightforward. In this multi-part column, I will attempt to simplify the topic and provide information that will enable any RV owner with basic technical skills to identify and troubleshoot RV electrical problems.
A logical place to start is with the 12V DC system. The 12V system provides power to all the interior lights (although there may be some 120V lighting in some coaches), range hood, water pump, vent fans, and some entertainment systems. It also controls many of the LP, and even 120V AC, appliances. This causes many owners to scratch their heads when troubleshooting AC or propane problems with their coaches, not realizing that the root of the problem lies with the 12V system.
The DC system begins with the batteries. Hopefully your coach has at least two deep cycle batteries powering the house system. Some dealerships provide only single batteries when they sell smaller trailers. They do this to save money, but a single battery is not sufficient, especially if the unit has a slide-out. If your RV has only a single battery, add another one.
The next question is whether to use 6V or 12V batteries. 12V batteries must be connected in parallel, which maintains the 12V, but doubles the current capacity. 6V batteries are connected in series, which doubles the voltage, but keeps the current the same. The current capacity is basically a measure of how long the batteries will last. Since 6V deep-cycle batteries contain much larger di-electric plates, the current capacity of a single 6V battery is more than twice that of a comparable 12V battery. The result is that using 6V batteries provides more current capacity than two 12V batteries, making it a better option. If you use primarily shore power for your RV, the battery question isnot as critical, and you can certainly save money by using 12V batteries, but the extra power capacity really comes in handy when you find yourself unexpectedly without shore power. Although it is true that the more batteries the better, this is not usually practical. Generally speaking, the ideal solution is to have four 6V batteries installed in the coach, any more than that takes up too much space and may create weight issues. If you have room in your battery bay, or you can create the space, I highly recommend the four battery setup. This requires a series-parallel wiring scheme. The details of this are outside the scope of this article, but wiring information for series, parallel, and series-parallel can be found on the internet.
Next week I will move on to the 120V AC electrical system.
About the Author:
Steve Froese, an avid RV owner, traveler, and Coach-Net member since 2013, is the principal of “A Word to the Wise Technical Communications”, a published RV author, certified RV technician, and licensed Professional Engineer. He frequently collaborates with the “RV Doctor”, Gary Bunzer, and has worked with the RVIA/RVDA as a technical and training writer and consultant. Professionally, he works as a quality engineer and musician. Watch for more of Steve’s work in upcoming Coach-Net publications.
Jean-Marie COUTAUD. said:
Just a little comment about parallel batteries in our design.
If you have 2 or 12 batteries in parallel, the positive connector is on the first battery in the row and the negative connector is on the last battery in the row.
J-M Coutaud, Electronic technologist retired.
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