Lesson 5: Generators


Nearly all motorized coaches will come with an onboard and integrated generator. The generator should be rated large enough to support the load your coach was designed for – usually between a 6500 and 8500 watt generator (to handle roughly 50 amps of service). The generator is doing a lot of work when it’s running: not only is it supplying power to the house, but it is charging batteries as well. This can create a large draw, hence why some generators actually exceed 50 amps (6000 watts).

In this lesson, we’ll cover the basics of the generator. Here are a few important tips to know:


– Don’t be afraid to run it! Once you turn it on, leave it on for a couple of hours! No 10-minute-bags-of-popcorn!

– You can run the generator while you’re driving. That’s how you keep your passengers in the house cool!

– The generator feeds off your gas tank. Once your tank is down to 1/4 full, the generator will starve and cease to run.

MasterTrack Lesson

Your coach is either a 30 amp or 50 amp variant. This refers to the power the coach was built to receive/use. Each item that requires electricity uses a certain amount of power (measured in amps or watts). If you turn on too many items, and go over your “amp” limit, you will trip a breaker (either in the coach or at the shore power receptacle). Therefore it is important to know and understand how power works in your coach.

Your power can come from 4 sources: Shore power (from a house or pole), generator power, solar power, or battery power.

  • Shore power: This describes the power when you “plug in” your coach to a power receptacle, either at a house or campground. You can use a ‘dog bone’ to convert your shore cord to the available power receptacle. 50 amp power is actually comprised of TWO 120 volt lines, versus a 30 amp connection is only one 120 volt line. There is often a delay between power and when it turns on in the coach… this is a safety pause…
  • Generator power: This power comes from your generator when it is running. Generators are often described by their wattage. For example, you may have an Onan 6000 watt generator, or a 3000 watt generator. Your coach should be equipped with a generator sufficient to run your major electric appliances together. This is usually measured by whether you can have your fridge on and run both air conditioners at the same time! Very few people will be able to power a microwave on top of all of that – but we’ll get to that later!
  • Solar power: Some owners opt to keep their batteries charges by putting solar panels on top of their RV. This is becoming more popular as the prices drop, however it is still an expensive option.
  • Battery power: This is the main source of power when not plugged into an outlet somewhere. Your RV will have a number of ‘house’ batteries – probably between 4 and 8, and a couple of ‘chassis’ batteries. The ‘house’ batteries are for all of your electrical outlets, and your chassis batteries are for starting and running the engine (like your car battery).

One more thing you must know is amps and watts. These are just measurements of power. They are just conversions of each other, meaning is something uses 5 amps, and you know your volts, you can calculate watts. You only need to know this because not all of your appliances will give you the amps used, but instead will measure it in watts. For example, a space heater will usually say 1,000 watts low – 1,500 watts high. This means that on the low setting, the heater uses 1,000 watts, and 1,500 on high. This doesn’t tell you amps. Yes, it’s math, but it’s easy to determine one or the other if you have the right information. The formulas are:

Watts = Amp X Voltage

Amps = Watts / Voltage

So our space heater from above on high will use 12.5 amps (since 1500 watts / 120 volts = 12.5 amps). You may never need to know this, but you might be surprised how helpful it is to know!

Auto gen-start

AGS stands for Automatic Generator Start. This is an optional module, but it is becoming a standard feature. This allows your coach to remotely start the generator upon certain conditions. These conditions are often low voltage or high temperature. For a low voltage start, the generator will start after the volts remain below a configured minimum for a short period of time. For high temperature, this is often to keep the coach cool on hot days, for convenience or for pets. First the A/C gets set, then the AGS will monitor the temperature and start the generator if it gets too high, which should turn on the A/C.

If the AGS turns the generator on, it will shut off after a preconfigured time. Remember, if you manually start the generator, you must also stop it!

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