When looking back at my posts, I thought I would pass on some of my knowledge on what I know about the electric system on your RV. But first a bit about me.
I am not a certified RV technician, but I am a Ceritfied Master Automotive Technician. I was in the field turning wrenches, for many years and then decided to go into teaching automotive for over 19 years. OK with that being said lets get started.
The Basics. We'll start with the 12 volts system first. The heart of the 12 volt system is your battery(ies) on your unit. Voltage is devided into two catagories. One Alternating Currect and the other is Direct Current, often called in the field ac or dc volts. We will be dicussing the dc voltage.
DC voltage is commonly refered to and associated with batteries, from the ever so popular AA's to the one in your RV. At this time you might be thinking that you need to get a voltmeter that measures both ac and dc, good thought. Measuring the voltage across the terminals on the battery is simple and should read about 12.5 volts. OK sounds easy enough but when I check mine is reads around 13.8 volts. Uh Oh, do I have a 13 volt battery instead of a 12 volt one? No what you are measuring is the charging volts going into the battery.
When you are plugged into shore power you have what they call in the industry a "converter". This is a fancy word for a "battery charger". Sometimes when your vehicle is connected to the RV, your vehicle's charging system may charge the battery when driving. So just like in the auto repair shop the charger is plugged into the outlet and "converts" ac into dc volts to keep the battery up.
So what is being used by the battery in my RV? Well your fridge may run off of the battery and propane (that's a different story). Let's see....Some of your lights, the furnace and the water pump for running water from your tank. Now lets take a ride and park the RV where there is no shore power, the RV is on its own.
What can I use: Well the fridge is still cold, I have some lights, I can take a shower, and have hot water. The hot water tank (on most units) ignites the propane by way of the battery.
What won't work is the tv's, microwave, coffee pot, hair dryer, basically anything that plugs into an outlet won't work and this includes the air conditioning unit. All of these items require ac voltage.
To maintain your battery is very simple. About once every two weeks go to the battery compartment and check the water level. Fill accordingly, and make sure the connections are tight. Oh I forgot, the battery also operates your sides and leveling legs on a 5th wheel. You may have heard that you should only use distilled water in your battery. This is true but tap water will work just fine.
Now lets talk about when something doesn't work. We'll say some interior lights. The system is protected with fuses just like on your car or truck. Somewhere in your unit you will find a fuse box and it should be marked which fuse controls what circuit. Find the fuse that controls your lights and check to see if has blown, if it has replace it with the same one and not a lesser or more rating than the one that has blown. If you are not sure check your owners manual. OK the lights are back on but one has to think, what caused the fuse to blow in the first place? If you put the new fuse in and it blew right away then you have what we call a "short to ground". This is something that a qualified service technician needs to look for.
I hope that I have gave you some information that will help in understanding your 12 volt system. A few maintance items once every two weeks and you are on your way in taking care of your battery.
Until next time................Be safe.