The electrical systems on our motorhomes are, aside from the drivetrain and its associated systems, the most complicated, error prone and least understood. I will attempt to provide some understanding of these systems so you can more efficiently operate them, and hopefully have less issues, or solve the ones you may encounter. I am not an electrical engineer, nor does the information below cover everything there is to know. It is to my knowledge correct, however in the case of a discrepancy with manufacturers literature the latter shall prevail. If you find any errors, or a better way of saying things, please let me know. Much of this many of you will already know. Bear with me as I am trying to help all, including those that are starting at the beginning. Much of the following is valid across all models and years. Where there are known differences I will highlight them. I do NOT know the specifics of all models. I most familiar with the early 2017 38A I own.
First off I will touch on some basic electrical concepts so as to better be able to explain the specific systems. Electricity is energy. It is the power that lets electrical devices do “work” for us, be it light up the room or dry the laundry. It is generated, stored and distributed to the users in a variety of ways. It comes, for us, in two types: AC: which stands for Alternating Current where the electrons (small sub-atomic particles) “run” back and forth, and DC, Direct Current, where the electrons run in a loop through the various circuits.
The potential of the electricity is expressed in Volts. The current that actually flows is expressed in Amps. Some people say it’s like a river…. Voltage is how steep and fast it is, Amperage is how wide and voluminous it is. The combination of the two determines how much work the electricity does and is expressed in Watts. This is also how the requirements of an electrical device are rated, for example a 1500W space heater…… There is one (and I promise the only one) formula that is very important to know:
Watts = Volts times Amps
If you have a 2400W (Watt) microwave operating at 120VAC (Volts AC) it will draw 2400W/120VAC= 20A (Amps) If you have a 24W light that operates on 12VDC, it will draw 24W/12VDC= 2A. If you run said light for an hour, you have used 2AH Amp Hour. Amp Hours come into play when you want to store electrical energy in a battery, and quantify its capacity.
We can convert electricity from one form to another, ie AC to DC or DC to AC. Using the knowledge above we can calculate what we can, and cannot do with the equipment installed. For example, why we CAN run the fridge on inverter, but can NOT run the air conditioning on inverter.
I highly recommend you buy a multi meter. A small device that can measure AC and DC voltage or test for “continuity” in a circuit (as opposed to a broken circuit). Slightly more expensive ones can measure AC or DC amperage. They are not expensive and there’s a gazillion Youtube videos on how to use them. Electricity is PURE physics. No voodoo (although we call “gremlins” when we don’t understand why it’s doing what it’s doing.) Trouble shooting is a logical process of elimination. Start at the energy source and work your way down the line until you find the problem. People tend to guess at what the problem is, often referring to what the problem was some other time. You can end up doing circles around the real problem….. So, with some basic knowledge we will now delve into the specific systems.
Note: I will refer to alternating current as AC. I will refer to an Air Conditioner as an A/C.