Estimating Power Requirements
Inverter Wattage Rating Chart
Formulas and Examples for 12 & 24 Volt DC Systems
This “Rule of Thumb” is intended as a general guide for estimating the DC amps required to operate a
DC to AC inverter. Since the calculations yield approximate values, an appropriate safety factor should
be considered when designing and specifying system components, such as wire size and length.
12 Volt DC Systems
Formula:
Example:
Answer:
12 volt inverters require approximately one (1) amp of DC input for each 10 watts of
AC output.
How many DC amps will a Vanner 12 volt inverter require to operate three 500 watt
quartz lights, or a 1500 watt electric heater?
1) Total watts = 1500
2) 1500 watts/10 (from formula) = 150 amps
This is the DC current the inverter will use to operate the 1500 watt load. Note - if
this 150 amps is drawn from the battery for one hour, 150 amp hours (AH) of
battery power will be used. To support 150 amp hours of battery power, 300 amp
hours of battery capacity is required.
24 Volt DC Systems
Formula:
Example:
Answer:
24 volt inverters require approximately one (1) amp of DC input for each 20 watts of
AC output.
How many DC amps will a Vanner 24 volt inverter require to operate three 500 watt
quartz lights, or a 1500 watt electric heater?
1) Total watts = 1500
2) 1500 watts/20 (from formula) = 75 amps
This is the DC current the inverter will use to operate the 1500 watt load. Note - if
this 75 amps is drawn from the battery for one hour, 75 amp hours (AH) of battery
power will be used. To support 75 amp hours of battery power, 150 amp hours of
battery capacity is required.
Average Wattage Ratings of Products
Operated from Vanner Inverters
Air Conditioning, 9000 Btu
Air Conditioning, 13,500 Btu
Air Conditioning, 16,000 Btu
Blender
Broiler
Carving Knife
Can Opener
Clock
Clothes Dryer
Clothes Washer
Coffee Maker
Corn Popper
Curling Iron
Continued on reverse side
Wattage
Min
Max
1100
1800
2200
200
1200
100
525
500
2200
3500
4500
800
1800
95
150
2
4900
5000
1500
575
40
Ambulance photo courtesy of Horton Emergency Vehicles. Solar Panel photo courtesy of DOE/NREL and Warren Gretz.
Utility Truck photo courtesy of Fleet Electric. Bus photo courtesy of Neoplan USA.
Experience the Power.
Typical Product
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Estimating Power Requirements
Inverter Wattage Rating Chart
Average Wattage Ratings of Products Operated from Vanner Inverters
Typical Product
Wattage
Min
Max
Deep Fryer
Dehumidifier
Dishwasher
Disposal
Drill
Electric Air Cleaner
Electric Blanket
Electric Knife
Engine Heater
Fan - Window
Furnace Fan
Flood Lights
Freezer
Frying Pan
Grinder
Hair Dryer
Hair Rollers
Heating Pad
Hot Plate
Hot Water Dispenser
Humidifier
Ice Cube Maker
Impact Wrench
Iron
1200
650
1200
1500
1500
50
250
100
750
200
400
2000
800
1500
1500
1500
350
60
1500
1400
200
300
900
1200
Induction
Motors
Starting Watts
1/4 HP
½ HP
1 HP
2 HP
900
450
250
100
300
450
1000
1000
500
125
500
250
625
Running Watts
750-1500
1500-3000
3000-6000
4000-8000
Corporate Office:
Vanner, Inc.
4282 Reynolds Drive
Hilliard, Ohio 43026
Tel: 614-771-2718
Fax: 614-771-4904
©Copyright 2001, Vanner, Inc.
Printed July 2001
“Vanner” and “Vanner /Sine-wave Design” are trademarks of Vanner, Inc.
700
1175
1950
2900
Typical Product
Knife Sharpener
Makeup Mirror
Microwave Oven
Mixer
Personal Computer
Pipe Threader
Plastic Pipe Electro Fusion
Radio
Range
Refrigerator
Shaver
Slow Cooker
Space Heater
Stereo System
TV - Black & White
TV - Color
Toaster
Trash Compactor
VCR
Vacuum Cleaner - Home
Vacuum Cleaner - Shop
Water Heater
Water Pump
Wattage
Min
Max
800
80
150
1400
300
30
50
50
75
1000
400
35
400
840
40
20
1600
150
350
1500
3900
25
12200
1625
75
200
1500
400
100
200
1400
800
75
900
1380
4500
1000
Notes:
1. The electrical power consumed by an electrical device is measured
in watts. This information is essential to proper inverter selection.
Wattage may be found on the appliance nameplate or by multiplying
the AC voltage (120 volts) by the running current (amps).
2. The wattage required to start certain motor driven loads could be 3
to 10 times their normal running wattage. The starting watts for a
motor are obtained by multiplying the locked rotor current by the AC
voltage.
3. Induction Motor running watts obtained from the National Electric
Code Handbook. The above power ratings should only be used as a
guide.
800-AC POWER
www.vanner.com
e-mail: pwrsales@vanner.com
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