Warning, Helpful formulas – Power Drive 1500 User Manual

Page 8

expect an operating time of 2 to 3 hours. It is recommended that you start
your vehicle once an hour when using the RPPD1500 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.

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AC Watts divided by 12 x 1.1 = DC Amps
This is the size vehicle alternator you would need to keep up with a specific
load; for example, to keep up with a continuous draw of 1000 watts, you
would need a 91 amp alternator.

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Multiply the power by the operating time. To determine how many 12-volt amp
hours will be consumed, divide the watt hours by 10.
Example: 150 Watts x 1 Hour = 150 Watt Hours
150 Watt Hours ÷ 10 = 15 12 Volt Amp Hours