- Thu, Nov 1, 2007
Late Fall Greetings from the Heartland….
Hello again from Nappanee! Here's hoping this writing finds you enjoying the beautiful colors and crisp mornings this time of year brings. The camp fires are all toastier, the hot chocolate is flowing, and the wardrobes change from cotton to cardigan. Before you know it we'll be roasting chestnuts on an open fire and Jack Frost will be nipping at our noses… but let's not get ahead of ourselves. Instead, let's savor the moment, the beautiful colors, and the great camaraderie.
Since we often bring out our space heaters and electric blankets with this change of seasons, this is probably a good time to talk about small appliances and some simple electrical common sense items. We all have those "plug-in" accessories we bring along in our units to make life a little nicer and more like home. Items like hair driers, curling irons, laptops, space heaters, coffee makers, and so on all help us in their own way, and are certainly common place in virtually any RV you enter. They do, however, have their own set of rules you must abide by… actually, you don't have a lot of choice because of how electricity and circuit protection works. Dealing with appliances (large and small) that use electricity means living within limitations. Sometimes those limitations are large, sometimes they are small, it just depends on how much current you have available. Let's look at some of those limitations.
I hate this part… there's always math in these things… let's see, where's that calculator….
Anyway… each appliance requires a certain amount of electricity to operate. It will draw a certain amount of "amperage", or "wattage" to operate. Unfortunately, there isn't always enough amps or watts to go around. There are enough outlets in most units to plug in half your worldly possessions, but try to run them all at once and what do you get - tripped circuit breakers and a cold, dark, quiet unit. That is the whole purpose of circuit protection; to insure the electrical circuits are not overloaded, and to make sure electrical short circuits are stopped before they can do any damage.
So how do you keep the lights on and the appliances operating? Learn to live within your limitations. So what's the first thing to do? Learn what those limitations are. Most units have either 30 or 50 amps of incoming electricity available to operate those appliances. That means you've got 30 or 50 amps of available current to operate them.
Every electrically operate appliance you own has some sort of label on it that tells you how much current it draws while in use. These labels will rate the current usage in either amps or watts so you will know how much of your available power it will consume. You can use a couple of electrical "laws" (or formulas) for calculating or converting amps to watts, watts to amps, and so on. "Ohms Law" defines the relationship between Power (P), Voltage (E), Current (I), and Resistance (R).
Using "Ohms Law" calculation chart, you can calculate amps, watts, and so on. Let's try something here; let's say we have a 1500 watt hair dryer. We want to know how many amps it is drawing so you know if you can use it while some other appliances are in use. Using the formula in the "I=Current" box, we know we can determine amps by dividing the watts the appliance uses by the voltage: 1500 watts 110 volts = 13.63 amps. Hmmm… better hold off on popping that popcorn while the hair dryer is in use. Knowing what appliances are on in the unit and how much current is being used will help you avoid those embarrassing black-outs that occur when the breaker out on the post trips.
Something else to keep in mind is the "hidden" draws on your power source; those items that use electricity without you consciously turning them on. For example, a convertor or inverter will draw some current as it charges your batteries. In the case of a large inverter charging a bank of weak batteries, it's possible that the charge circuit could draw 15 - 18 amps. Also, don't forget your refrigerator… it needs DC voltage to operate the circuitry, and AC voltage to run the heating element, all of which add to the load. The loads can be light, or heavy, but they all take their own "bite" out of the available current you have.
Of course, through the miracle of modern electronics, we have some wonderful devices now that watch those loads for you, and turn them on and off automatically based on pre-assigned priorities to minimize the chances of you attempting to draw too much current. Many modern inverters incorporate an "EMS" (Energy Management System) program that monitors incoming volts and amps, and will turn circuits on and off according to current supply and demand. Pretty cool, huh?
Well, hopefully there weren't any "shocking" revelations there. We just have to remember to respect electricity, and use it conservatively; after all, electricity IS our friend! We hope this information is helpful. Thanks again for tuning in, and we will see you here next month!