Power Drive 300 - Manual (Page 7)

Operating Limits
Power Output
:
The inverter can deliver 300 watts for about 60 minutes. The inverter must
cool for 15 minutes before it can resume operation at 300 watts.
NOTE: Operating time will vary depending upon the type, capacity charge
level of the battery, and the power draw of the AC products you are using.
With a normal vehicle battery and a 100 watt load (such as a small television)
you can expect an operating time of 2 to 3 hours. It is recommended that you
start your vehicle once an hour when using the RPPD300 for extended
periods of time to prevent draining the battery.
WARNING
: To prevent personal injury or loss of life, never start or leave your
engine running in a poorly ventilated area such as a garage.
Helpful Formulas:
To Convert AMPS to WATTS: AMPS X VOLTS = WATTS
To Convert WATTS to AMPS: WATTS ÷ VOLTS = AMPS
These formulas yield a close approximation of the continuous loads of a
product.
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Multiply: WATTS X 2 = Starting Load
This formula yields a close approximation of the starting load of the
appliance, although some may require an even greater starting load. NOTE:
Induction motors such as air conditioners, refrigerators, freezers and pumps
may have a start up surge of 3 to 7 times the continuous rating. Most often
the start up load of the appliance or power tool determines whether an
inverter has the capability to power it.
For example: You have a freezer with a continuous load of 4 amps, and a start
up load of 12 amps:
4 amps x 120 volts = 480 watts continuous, 12 amps x 120 volts = 1440 watts
starting load
You would need an inverter with peak-surge rating greater than 1440 watts to
run this appliance.