Estimating Power RequirementsInverter Wattage Rating Chart

Formulas and Examples for 12 & 24 Volt DC SystemsThis “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 SystemsFormula: 12 volt inverters require approximately one (1) amp of DC input for each 10 watts of

AC output.Example: How many DC amps will a Vanner 12 volt inverter require to operate three 500 watt

quartz lights, or a 1500 watt electric heater?Answer: 1) Total watts = 1500

2) 1500 watts/10 (from formula) = 150 ampsThis 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 SystemsFormula: 24 volt inverters require approximately one (1) amp of DC input for each 20 watts of

AC output.Example: How many DC amps will a Vanner 24 volt inverter require to operate three 500 watt

quartz lights, or a 1500 watt electric heater?Answer: 1) Total watts = 1500

2) 1500 watts/20 (from formula) = 75 ampsThis 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.

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Average Wattage Ratings of Products Operated from Vanner Inverters

Typical ProductWattage

Min Max

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

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.

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800-AC POWERwww.vanner.com

e-mail: pwrsales@vanner.com

Corporate Office:Vanner, Inc.4282 Reynolds DriveHilliard, Ohio 43026Tel: 614-771-2718Fax: 614-771-4904©Copyright 2001, Vanner, Inc.Printed July 2001“Vanner” and “Vanner /Sine-wave Design” are trademarks of Vanner, Inc.

Average Wattage Ratings of Products Operated from Vanner Inverters

Typical ProductWattage

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

900

450

250

100

300

450

1000

1000

500

125

500

250

625

1200

650

1200

1500

1500

50

250

100

750

200

400

2000

800

1500

1500

1500

350

60

1500

1400

200

300

900

1200

Typical ProductWattage

Min Max

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

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

Induction Motors Starting Watts Running Watts

1/4 HP

½ HP

1 HP

2 HP

750-1500

1500-3000

3000-6000

4000-8000

700

1175

1950

2900

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.

Estimating Power RequirementsInverter Wattage Rating Chart