When you need 110 volt power, but you live “off the grid” on a boat, RV, in a cabin or due to emergency circumstances; an inverter can turn a battery (12 volts, direct current) into 110 volts (household alternating current) of useful power. Inverters and Inverter / Chargers are manufactured by industry respected names like Magnum Energy , Go Power! , Xantrex Technology and others, There are several considerations when choosing an inverter.
Your Power Usage – most tools, appliances and lights are rated for power draw in the form of watts. A 60 watt bulb uses 60 watts! If an item is listed in “amps”, then multiply the amps draw (rated at 110 volts) by 110. A motor that requires a 12 amp start up would use approximately 1320 watts.
Your Power Supplied – you need to have a battery supply that can keep up with your needs. The longer you want to run without charging and the higher the watt usage, the more batteries you need.
Inverters are primarily chosen on 3 criteria:
- The maximum number of watts of power at 110 volts.
- The type of Sine Wave they put out.
- The charging ability and capacity.
Inverters are available from 300 watts to over 4000 watts. The choice for wattage is dependent upon usage and the ability to draw on a battery reserve to meet the power demand. Any inverter over 300 watts should be connected as directly to the battery as is possible. Remember, motors at start up may use 20-50% more power than is needed for running operation.
300 – 500 watts: For a single household appliance, TVs (up to 27″), VCR, desktop computers, other mobile office equipment. Most of these connect via a 12-Volt vehicle plug. Great for keeping up with a laptop, portable TV or other small items when travelling.
600 – 1500 watts: For larger household appliances, large screen TVs, 5-12 amp power tools. Most of these inverters have three or more grounded outlets for powering several products at the same time and are connected directly to the 12-volt battery.
1750 – 2500 watts: For any household appliances, larger power tools, microwave ovens, toasters, and hair dryers. All of these inverters are designed for direct connection to the battery network and can generally supply 1500 watts of continuous power. These may have a charge built in as well as some self monitoring features.
3000+ watts: With output power generally rated at 90% for continuous loads, these inverters can power virtually all household appliances and equipment. For loads of this magnitude, special wiring and battery banks may be required. Most of these large units have chargers to top the batteries built in to them and are self monitoring.
There are two types of sine wave produced by inverters; pure sine wave or modified sine wave. Pure sine wave is a nice smooth sine wave current similar to what you get when you plug into your home outlet. Modified sine wave is a slightly ‘square’ or boxed off wave that is cheaper to set up in the world of electronics. Most items will run from well to ‘ok’ on a modified sine wave, but there are some exceptions where the electronics or motor are a bit fussier.
Lastly, if you have your inverter / battery set up so that you can recharge frequently as is the case with a boat, RV or backup power source for emergencies, an inverter / charger will work well. When AC power is available, the inverter/charger recharges the supply batteries while also allowing AC power to pass through and power the system AC loads, such as a television set or microwave oven. When AC power is disconnected, the unit inverts DC battery power into AC electricity.