Specifications

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have to be changed out for one that converts 12 VDC to 100VAC at 50 hertz, as this is
the standard form provided by the electricity grid in Tokyo.
The modified sine wave inverter is the less desirable of the two types, mainly because
of its lower efficiency and the possibility that it could interfere with some sensitive
electronics such as TV‟s, motors, and medical equipment. There is also a small risk of
damage to electronics powered by such an inverter as they have been known to have
brief jumps in current. The signal from a modified sine wave inverter is sometimes
referred to as hybrid, meaning in this case that it is a mix between a sinusoidal and a
square wave. In order to create such a signal, these inverters simply supply various DC
voltages for specified time intervals in a repeated staircase like climbing and
descending fashion.
On the other hand, the signal provided by a pure sine wave inverter is exactly what the
name says, a perfect sine wave. This is exactly the same type of signal that is provided
by the power grid, and it virtually eliminates the possibility of interference or damage to
connected electronics. Because of its signal, a pure sine wave inverter is usually also
slightly more efficient than a comparable modified sine wave inverter. Most modified
sine wave inverters have conversion efficiencies between 85% and 90%, but pure sine
wave inverters usually have slightly over a 90% efficiency rating. The figure below
shows the difference in the signals provided by the two different inverter types. As
always, there is a cost for the better characteristics of pure sine wave inverters. The
construction and circuitry is much more complex, and they generally cost about three
times as much as a comparable modified sine wave inverter.
Figure 15 - Modified Sine wave inverter signal vs. pure sine wave inverter signal
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Nowadays, most commercially available inverters also include other important features,
which are important to consider when the final decision on a power inverter is made.
One such feature is a low battery shut down. This is important because it keeps the
battery from being drained past the point at which permanent damage may be inflicted
on it. Another important feature is overload alarms. Most purchasable power inverters
include overload alarms that sound or shut the inverter off and put it in a safety state
when too much power is drawn from the inverter, too much DC voltage is supplied,
temperature gets too high, or a short circuit is detected. Another helpful feature, known