An inverter boosts your DC power 10 to 20 times by switching the power to create pulses of electricity in AC. This switching process is generally done by high frequency power mosfets.

There are two forms of electric wave output generated by an inverter, pure or true sine wave and modified sine wave. To understand the difference we need to look at their performance.

PureSine inverters

Pure Sine wave is the same as the power you have in your home. It is very clean and is the optimum for performance. Please take look at the graph below. You will notice the wave is very smooth. This smooth pure sine wave is most efficient. Therefore, appliances such as TVs, computers and stereos run cleaner and easier. Also, Pure Sine wave generates less heat than other waveforms.

Modified Sine wave or Square wave inverters

Modified Sine wave is an output that tries to imitate pure sine waves but comes up a little short. Nevertheless, modified sine wave inverters have their advantages. Modified sine wave inverters are great to run appliances and equipment such as power tools, non-digital microwave oven, lights, and other motor driven loads.

The main downside to modified sine wave output is slight interference. This interference can be seen on some televisions and computers. It will not cause any damage, but can be a little annoying. The upside to modified sine wave inverters is they will run most appliances, and are very affordable.

These figures are approximate representations. The actual power consumtion of your appliances may vary from these figures. Check the power tags on the appliances.

The inverter size you choose depends on the power in watts (or current in amps) of the appliance/equipment you want to run (find the power consumption by referring to the specification plate on the appliance or tool or you will find the information in the appliance manual. If this information is not available, check the table above). You need to know both the continuous rating in watts or amps; and the peak/surge rating in watts or amps. Without this information any further calculation is not possible.

CONTINUOUS vs PEAK/SURGE WATTS

Inverters are rated in continuous power and peak/surge power. Continuous power is the total WATTS the inverter can support indefinitely while peak/surge power is the amount of power that the inverter can provide for a brief period, usually when the equipment/appliance starts up. Induction motors driving such devices as air conditioners, refrigerators, freezers, pumps, etc. may well have a start up peak/surge of 3 - 7 times the continuous rating.

CONVERTING AMPS TO WATTS

Multiply the equipment/appliance AMPS x 230 (AC voltage) = WATTS (approximate)

WORKING OUT THE POWER

Multiply the equipment/appliance AMPS x 230 V (AC voltage) to give the approximate WATTS or AC power.

CALCULATE APPROXIMATE STARTUP LOAD (PEAK/SURGE WATTS)

Multiply the equipment/applicance WATTS x 3 = PEAK/SURGE WATTS (approximate)

So if you want to run an appliance with a continuous load of 5 Amps and a peak load of 15 Amps :
Power : V x I = VA i.e. 230VAC x 5A = 1150 Watts continuous power
Power : V x I = VA i.e. 230VAC x 15A = 3450 Watts peak/surge (also known as start or inrush current)

You would need an inverter with a continuous rating of approximately 1500 watts and with a peak/surge rating of approximately 3500 watts. It is always advisable to build in a safety factor by overrating the continuous rating by 20 - 25% .

Always mount the inverter in an environment which is:

• Well ventilated
• Not exposed to direct sunlight or heat source
• Away from water, moisture, oil or grease
• Away from any flammable substance

This depends on the battery size selected and the type of batteries used.

Deep cycle (marine/solar) batteries generally have the highest reserve ratings. They are specifically designed to withstand repeated drains of power and recharging.

Vehicle start batteries should not be discharged below 90% charged state, and marine/solar deep cycle batteries should not be discharged below 50% charged state. Doing so will shorten the life of the battery based on most battery manufacturers?recommendations.

Note: If you intend to use power tools for commercial use, or any load of 200W for more than 1 hour regularly (between battery recharging) we recommend installing an auxiliary battery to provide power to the inverter. This battery should be a deep cycle type and sized to meet your run time expectations with the vehicle engine off. The auxiliary battery should be connected to the alternator through an isolator/regulator module to prevent the inverter from discharging the vehicle start battery when the engine is off.