Mains Power Inverters Tips & FAQs

Using The Cigarette Lighter Plug:

The cigarette lighter lead supplied with the 400W inverter is suitable for operating the inverter at power outputs up to 150 Watts. This is because most vehicle cigarette lighter circuits are only rated at 15 to 20 Amps. If you go over this it will blow the fuse for the cars cigarette lighter socket.

To operate at full power, either use the battery clip cable supplied or directly wire to the power source with user supplied wire and fuse.

Rated Versus Actual Current Draw Of Equipment:

Most electrical tools, appliances and audio/video equipment have labels that indicate the power consumption in amps or watts. Be sure that the power consumption of the item you wish to operate is rated at the specified watts or less (if the power consumption is rated in amps AC, simply multiply by the AC volts to determine the wattage). The inverter has overload protection, so it is safe to operate equipment rated at the specified watts or less. The inverter will shut down if it is overloaded. The overload must be removed before the inverter will restart; resistive loads are the easiest for the inverter to run. However, larger resistive loads, such as electric stoves or heaters, usually require more wattage than the inverter can deliver on a continuous basis.
Inductive loads, such as TVs and stereos, require more current to operate than do resistive loads of the same wattage rating. Induction motors, as well as some televisions may require 2 to 6 times their wattage rating to start up. The most demanding in this category are those that start under load, such as compressors and pumps. Testing is the only way to determine whether a specific load can be started and how long it can run. The unit will simply shut down if it is overloaded. To restart the unit after a shutdown due to overloading, remove the overload and if necessary turn the power switch Off then On.

CAUTION: This inverter will not operate high wattage appliances or equipment that produce heat, such as hair dryers, microwave ovens and toasters.

Power Source Requirements:

The power source must provide between 11 and 15 volts DC and must be able to supply the necessary current to operate the load. The pwoer source may be a battery or well regulated DC power supply. To obtain a rough estimate of the current (in Amps) the power source must deliver, simply divide the power consumption of the load (in watts AC) by 10.
Example: if a load is rated at 250 Watts AC, the power source must be able to deliver:

250 divided by 10 = 25 Amps

Caution: The inverter must be connected only to batteries with a nominal output voltage of 12 volts. The unit will not operate from a 6 volt battery and will sustain permanent damage if connected to a 24 volt battery.

Battery Operating Time:

Operating time is dependent on the capacity and condition of the vehicles battery and the load being run. Battery capacity is measured in Amp/hours or Ah, eg 100Ah.

To give a rought estimate of the running time divide the Ah rating of the battery by the current (in Amps) that the inverter will draw for your specific load (see “Power source requirements” above).
Example: if a load requires the battery to deliver 25 Amps and the battery is rated at 100Ah:

100 divided by 25 = 4 hours

Therefore a 100Ah battery in good condition should be able to run a 250W load for approx 4 hours.

Note: The inverter may be used whether or not the vehicles engine is running. However the inverter may not operate while the engine is starting since the battery voltage can drop substantially during cranking.

Inverter Voltage Output:

Why do inverters output 230V and not 240V, will my equipment work?

Yes, as far as your equipment is concerned they are the same. In fact the voltage from your mains sockets at home while a nominal 240V varies. The official standard for mains supply voltage was harmonised across Europe in 2003 at 230V and for the UK was set as 230V with a tolerance of +10%/−6% (216.2V to 253V). In 2008 this widened to 230V ±10% (207V to 253V). Anything within this range is considered acceptable and won’t affect the operation of your equipment.

What does modified sine wave mean?

Mains voltage is AC (alternating current) where the charge periodically reverses direction (50 times per second in Europe), this alternating current forms a smooth sine wave as it changes from one direction to the other whereas the output of a modified sine wave inverter forms an approximation of a sine wave by changing in steps instead of a smooth transition. This method keeps the cost down is compatible with most electronic devices except for certain sensitive or specialised equipment. More expensive inverters are available that produce a closer representation of a true sine wave, these are commonly called pure sine wave inverters and the output is essentially the same as that from a domestic mains socket.