Practical Motor Home Inverter Applications

July 13, 2008

Two weeks ago week we looked at the type of inverters commonly used in motor homes. This week we will touch on applications of inverters in our home on wheels. We will deal with integrated types only, generally these are 2,000 watt output and larger. We will also focus only at the inverter operation, not the charger function.

The inverter basically takes 12 volt direct current from the batteries and inverts it to 120 volts alternating current, similar to that in your house.

In doing this, it produces either a M.S.W. (Modified Sine Wave) or a T.S.W. (True Sine Wave) depending on the make and model. Modified types are the cheaper of the two to produce, and are the ones found currently on the majority of motor homes today. True sine types are becoming far more popular recently. This is due to lower prices recently and more sine wave affected electronics that are being introduced into today’s modern coaches.

The inverter in a standard configured propane equipped motor home is generally wired to power the following.

TV’s, receivers and entertainment centers
Most duplex 120 outlets
Microwave
Awnings, if 120 VAC (Such as Gerard)
Refrigerator (If 120 volt AC)
Ice maker (If 120 volt AC)

The balance of AC powered loads such as air conditioners, hot water tank, electric stoves and of course, battery chargers only operate on shore power.

Some microwave models can be damaged if used to cook using a modified wave inverter. This damage can result in causing the efficiency to drop substantially after continued use. While wiring the inverter to the microwave outlet is normal, which at least keeps the clock on time, it may be wise to run the generator for any microwave cooking while boondocking. This applies to M.S.W. inverters, but is not applicable to T.S.W. installations. Additionally, some models of modern residential refrigerators may be susceptible to modified sine wave inverter current. The issue is control board related. This primarily affects newer all electric coaches. These really require a true sine wave inverter to assure trouble free operation.

Inverters in conventional propane equipped motor coaches are generally turned off when not required, particularly if dry camping. This is due to a continuing draw, albeit light, of electric current, even if all loads are off. First, there is a search mode that essentially searches for a load, even in stand-by mode. Secondly, TV’s, microwave readouts and many modern receivers use power in the “off” mode. The TV’s and receivers remain on stand-by to be instant “on”.

Inverters in all electric coaches are generally always left on. This is required as the refrigerator, if it is a residential type, is 120 volt AC only. Inverters can be left on even when connected to shore power. Once connected, the unit shuts down the inverter and operates as a charger and will automatically take over in the event of a power disruption.

Now, as if the inverter/charger didn’t do enough, there are models available with a built-in automatic generator starting board. These will automatically start and stop the generator as required to keep the batteries within operating voltage range. Additionally, the auto start can be wired to the air conditioning thermostat and provide instant start should the temperature within the coach rise above a user preset value. Once the temperature is within the set temperature range, it will automatically shut the generator down until the next event.

If you have never had a coach with an inverter/charger, you don’t know what you are missing. The convenience of having household power without the need for continually running the genset, is well worth the costs involved. If you already have an inverter equipped coach, you probably wouldn’t have a coach without one again.

With A Current Alternate View – Lug_Nut – Peter Mercer