UNDER CONSTRUCTION, updated 12/07/2020
A lot of us are unsure of how our RV electricity works and what we need, to get our appliances running. All is well as long as it does what it needs to do but once there is a problem we need to know how it works because that is the way we can troubleshoot. In this post, we explain RV electricity with easy to understand terms and examples. We first start out naming the various components of the 120 volts and the 12 volts systems and a little explanation. Later on, we dive deeper into the electricity functions of each individual part.
Every RVer should have some multimeters to test the pedestal and use it as a troubleshooting tool.
See this video link Basic uses of a multimeter for RVers
The best multi-meters to use (for a reasonable price) In my opinion are these;
Proster 6000 Counts Clamp Multimeter Digital Auto-Ranging Tester AC DC Current Voltage Clamp Meter with Temperature NCV TRMS Continuity Capacitance Resistance Frequency Diode Hz Test
Non-Contact Voltage Tester 100-600V (NCV)
How-To RV Hot-Skin Shock Demonstration
And if you want to test GFCI sockets this one;
How to check a regular Wall Outlet using this tester: https://www.youtube.com/watch?v=b6ilpnbWt_I
To start with the RV electricity there are 2 distinct different sources, AC and DC
AC or alternating current
this takes care of running the microwave, coffee machine, instant pot, and the TV. In general everything you can plug into a wall socket but also your air conditioner.
AC is 120 volts like at home.
DC or direct current
this takes care of our lights, control boards, slide outs, and levelers to name a few.
DC is 12 volts and mainly provided by the batteries
|AC 120 volts is needed for:
To run all our 120-volt appliances and gadgets we need to get 120 volts from somewhere, the easiest method is from the campground pedestal, using a so-called “dog bone” if necessary. First, make sure that you test the power, then plug in the cable and flip the breaker. Usually, the pedestal is on the driver side.See this link to read about “dog bones” and how to test a pedestal. Campground power (shore power) can be flaky because the load will vary depending on the weather (many air conditioners running) and the constant plugin and unplug on the pedestal it is less reliable than at home. A pedestal is always outside and may have insects inside that can make it unusable. Therefore you need to test it but also have a surge protector or EMS to prevent damaging the RV.See this link for a surge protector and EMS discussion.
A generator will provide you with the same 120 volts as a cable but uses the fuel you have to provide. Depending on your RV you have to plug the power cable into a different socket or directly into the generator. Motorhomes generally have an auto transfer switch that can automatically provide the power from the shore power or generator. Some built-in generators use the fuel that is also running your engine. They will stop if there is only 1/4 tank left so you do not get stranded.
An inverter can make 120 volts AC out of your 12 volts DC battery bank. Make sure you have enough batteries to provide enough power. The bigger the inverter the more overhead power it needs. Don’t mix up an inverter with a converter, the converter makes 12 volts DC out of 120 volts AC, the inverter makes 120 volts AC out of 12 volts DC.Watch this video and read the article to learn about Inverters and ConvertersPower inverters explained: https://www.youtube.com/watch?v=iIqhAX0I7lI(See the CONVERTER below)
|ATS (Auto Transfer Switch) (Not used in all RVs)
An auto transfer switch will automatically switch power without changing the cable between the generator and shore power. Most ATS will favor the generator and will not switch to shore power unless you stop the generator. In case you need to replace an ATS make sure you use the same amps.More about the ATS via this link from Mike Sokol
120-volt connections are protected by breakers. To reset a breaker switch it all the way to Off and then to On again, you should hear a click.NOTE:
DC voltage uses fuses.
|A GFCI outlet contains a sensor that monitors the flow of the electrical current through the wires, and when it senses a ground fault (in electrical terms, “fault” means any variation from the normal current), the GFCI, which also contains an internal switch, shuts off the flow of electricity in the outlet.
In RVs here are multiple outlets daisy-chained so you need to know where every outlet is and check all of them. When one is tripped upstream then all the downstream outlets will not work.
|DC explained: https://www.youtube.com/watch?v=VV6tZ3Aqfuc|
|Depending on your RV the (house) batteries provide 12 volts for;
Inverter (Makes 120 volts out of 12 volts)
NOTE: Most motorized RVs have one or two separate starter batteries, they are only used for starting the engine.
Want to know what to buy? Follow this link from Thomas to a great article that explains the cost and usage.
How a (car) battery works: https://www.youtube.com/watch?v=VnPRX5zQWLw
A converter provides 12 volts in case you have 120 volts via shore power or the generator. It converts the 120 volts AC to 12 volts DC and takes over from the batteries and/or charges the batteries.
(See batteries for 12 volts consumers)NOTE: The converter will not work when there is no 120 volts.Watch this video and read the article to learn about Inverters and Converters
|Charging the batteries
You surely can charge your batteries using a battery charger. We do that in the winter when we remove the batteries and store them in the garage.
Other options are:
While driving the engine alternator charges the batteries
Solar panels will also charge the batteries
Generator via the converter or inverter-charger
Shore power via the converter or inverter-charger
A converter makes 12 volts DC from 120 volts AC
| A note about solar panels;
Solar panels are only for charging batteries, nothing runs directly from the solar panel. In addition to the panels, you need a charge controller that regulates the charge voltage and sufficient batteries to store the power that the panels generate. Often times they also talk about the inverter although it is technically not part of a solar panel setup it is sized to match the power consumption and the battery’s capacity.A great 15 video series about solar by Thomas from I’m Not Lost I’m RVing click here!.
A lot of 12 volts lights and vehicle functions are protected with blade type fusesNOTE:
AC uses circuit breakers.
|Fuses other than automotive
There are a lot of different fuse types for 12 volts. Sometimes an inline fuse, a glass fuse, or just a resettable fuse. Inline fuses are often used in water heaters and furnaces or fuses that are accessible on a control board. Whenever you find a fuse or fuse box take a picture and save it on your computer, in that way you can find it again when needed.
How to find a short in your DC system using a clamp meter:
This is a 3 part series from Mike Sokol, a great video series that teach you most of the things you need to know!
AGM (Absorbed Glass Mat) Battery A lead-acid, maintenance-free battery.
Ah Capacity The ability of a fully charged battery to deliver a specified quantity of electricity (Amp-Hr., Ah) at a given rate (Amp, A) over a definite period of time (Hr.). The capacity of a battery depends on a number of factors: active material, weight, density, adhesion to the grid, number, design, and dimensions of plates, plate spacing design of separators, specific gravity and quantity of available electrolyte, grid alloys, final limiting voltage, discharge rate, temperature, internal and external resistance, age and life of the battery (bank).
Alternating Current (AC) An electric current that reverses direction at regular intervals. Sources of alternating current are shore power, generator power, inverter power or household current.
Ampere (Amp, A) The unit of measure of the electron flow rate of current through a circuit.
Ampere-hour (Amp-Hr., Ah) A unit of measure for a battery’s electrical storage capacity, obtained by multiplying the current in amperes by the time in hours of discharge (Example: a battery hat delivers 5 amperes for 20 hours delivers 5 amperes times 20 hours, or 100 Amp-Hr. of capacity.)
AWG (American Wire Gauge) A standard used to measure the size of the wire.
Current The rate of flow of electricity or the movement rate of electrons along a conductor. It is comparable to the flow of a stream of water. The unit of measure for current is ampere. Cycle In a battery, one discharge plus one recharge equals one cycle.
Direct Current (DC) Current flows continuously in one direction such as that from batteries, photovoltaics, alternators, chargers, and DC generators.
Gel Cell Battery A type of battery that uses a gelled electrolyte solution. These batteries are sealed and are virtually maintenance-free. Not all sealed batteries are the gel cell type.
Ground The reference potential of a circuit. In automotive use, the result of attaching one battery cable to the body or frame is used as a path for completing a circuit in lieu of a direct wire from a component. This method is not suitable for connecting the negative cable of the inverter to the ground. Instead, route the cable directly to the negative terminal of the battery.
LED (Light Emitting Diode) Indicator light.
NEC National Electric Code
Negative Designating or pertaining to electrical potential. The negative terminal is the point from which electrons flow during discharge.
Positive Designating or pertaining to electrical potential; opposite of negative. The positive battery terminal is the point where electrons return to the battery during discharge.
Volt The unit of measure for electric potential.
Watt The unit for measuring electrical power, i.e., the rate of doing work, in moving electrons by or against an electric potential.
Wet Cell Battery A type of battery that uses liquid as an electrolyte. The wet cell battery requires periodic maintenance; cleaning the connections, checking the electrolyte level, and performing an equalization cycle.