To make regular 120 volt AC electricity you need a Power Inverter. A Power Inverter increases the voltage, say from 12 volts to 120 volts, and changes the Direct Current into Alternating Current. The inverter is connected directly to the battery. Some inverters are so good at changing current that they provide a cleaner, smoother current than the one in your home. A Power Inverter can cost anywhere from $24.95 for a 150 watt modified sine wave inverter to $1,000.00 for a 5000 watt pure sine wave inverter (and up).   

Inverters and Sine Waves

Alternating Current forms a wave, a sine wave it’s called. Outside of the size of the inverter, the “purity” of the sine wave is a very important distinguishing feature to note in a Power Inverter.

There are basically two kinds of sine wave inverters in this context, the modified sine wave inverter and the pure sine wave inverter. The modified sine wave produced by the corresponding inverter is almost a perfect wave but not quite. Instead of being curvy and smooth, it’s boxy, more angular. The wave produced by the pure sine wave inverter, is, well, perfect, rounded and smooth. Just like what you have at home, maybe better. It’s a matter of filtering.

Modified sine wave inverters are much less expensive, smaller and lighter. Most devices will work quite well with them (check with the product manufacturer to be sure). Pure sine wave inverters run smoother, cooler, longer, and provide that very clean power more sophisticated, or sensitive equipment may require. They’re also considerably more expensive. This would be equipment like laser printers, medical equipment, digital clocks, electronic piano keyboards (otherwise they buzz), and portable computers to name a few things. (A portable computer can look like its functioning fine with a modified sine wave inverter but don’t believe it!) Lower end pure sine wave inverters can cost in the $110.00 area.

Choosing An Inverter Check List

A few basic things to look for/check in choosing your inverter are:

Is it made for a 12 volt battery? Most are. It will be on the specifications.

Is it big enough? Inverters are sold by watts. Add up the most watts you’d want to power at one time. (Many inverters have two or more outlets.) The wattage of the inverter must be higher than the total number of watts you’d want to run at one time including surges. A surge: often when devices first start up, they draw much more power than their normal operating rate. Inverters have what they call peak power or surge capacity which may be twice as high as their operating watts. This surge capacity only lasts for 10 seconds or so. Check your labels.

Do you need a pure sine wave inverter or is a modified sine wave inverter enough? See above discussion.

Most inverters have built in safety features like current overload protection and low voltage protection and lots of others. All these things make them pretty easy to use. You’ll find everything listed under “features’ or “specifications” in the product description. Except for the smaller inverters, most have fans to keep them cool. Some fans are on all the time. (It’s just a low level whirring noise.) Some only if they get warm. Others come on only at the beginning, at the surge. If you anticipate not liking that background noise while you’re reading for instance, look for one with no fan or one that only comes on at the “surge”, or when it gets hot.

Other Good Things to Know About Inverters

Like your outlet at home, an inverter handles an extension cord plugged into it fine and the length doesn’t affect the power. However, the further it is positioned wiring wise from the battery (the wiring between the inverter and the battery) the less power it may receive which may not allow it to function at its peak. Larger wiring/cable may be required. Being close to the battery is better.

A standard inverter designed to produce 120 volt AC electricity can’t run your 220 volt washer or dryer, ever.  

There are many sites that include estimated watts on common devices if you have trouble locating that information.  U.S. Department of Energy.


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