PowerDrive 1500 Owner's 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.
T T o o c c a a l l c c u u l l a a t t e e a a p p p p r r o o x x i i m m a a t t e e S S t t a a r r t t u u p p L L o o a a d d : :
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.
F F O O R R M M U U L L A A t t o o c c o o n n v v e e r r t t A A C C W W a a t t t t s s t t o o D D C C A A m m p p s s : :
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.
T T o o c c a a l l c c u u l l a a t t e e t t h h e e t t o o t t a a l l w w a a t t t t - - h h o o u u r r s s o o f f e e n n e e r r g g y y c c o o n n s s u u m m p p t t i i o o n n : :
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