You are not logged in or registered. Please login or register to use the full functionality of this board...
Have a Great Thanksgiving!

amp hours

Amp hour
Can someone explain to me the term amp hours? Specifically, say I have a total of 500 amp hours in my house battery bank.  I know I can only use a max of 250 of those amp hours without damaging my batteries.  My understanding is I can run an appliance using 1 amp for 250 hours.  Is that correct,  or am I hallucinating?

Clarke and Elaine Hockwald
1982 Newell Classic, 36', 6V92 TA
2001 VW Beetle Turbo
Cannondale Tandem
Cannondale Bad Boy
You are correct Clarke. You could use 1 amp for 250 hours or 10 amps for 25 hours or any other combination within reason. High amperage draws present their own issues but you have the concept. Look at the various lights, tv's, microwave, etc that you use, calculate the number of amps each draws, multiple that times the amount of time you think you will use that light or appliance per day and you can determine how long it will take you to use 250 amp hours. Since many of your loads are AC, you have to use an efficiency factor for the inverter to convert DC to AC.
Michael Day
1992 Newell 43.5' #281
To add to what Michael Said....

So the DC amp-hour of my battery bank is 600 amp-hours. (100 AH per battery x 6 batteries).
Watts are defined as Amps x voltage so my battery bank has (12.5 x 600) = 7500 Watt - hours (DC)

Here is where it gets interesting.

Lets convert the 7500 DC watt-hours to AC. (7500 watt-hours / 115VAC) = 65.2 amp-hours (AC).
Taking into account the inefficiency of the inverter means that we only get about 95% of this number or 62 amp-hours (AC).

Now that we have the AC Amp-hour capacity...lets use it for some examples...

The Headhunter 120 VAC pump consumes 10 amps while it is running. It can run for 6.2 hours (62 amp-hours / 10 amps) before discharging your battery bank.

A typical microwave may pull 8 amps while it is running. So...62/8 = 7.75 hours run time.

Remember that all the appliances only pull amps while they are working. The refrigerator pulls nothing until the compressor kicks on. To truly understand your battery capacity, you will have to estimate the amount of time each draw will be "on".

Hope this helps!


Here is a list of appliances and their typical AC draws....

Appliance or Electronic Equipment Estimated Amps
Air Conditioner (X number of A/C) 12-16 Amps
Blender 5-6 Amps
Coffee Maker 5-8 Amps
Compact Disc Player 1 Amp
Computer (Laptop) 2-3 Amps
Converter 1-8 Amps
Crock Pot 1-2 Amps
Curling Iron <1 Amp
Drill 2-6 Amps
Electric Blanket 0.5-1.5 Amps
Electric Fan 1 Amp
Electric Water Heater 9-13 Amps
Electric Skillet 6-12 Amps
Hair Dryer 5-12 Amps
Iron 5-10 Amps
Light (60 watt % 120V) <1 Amp
Microwave 8-13 Amps
Microwave (Convection Oven) 13 Amps
Refrigerator in AC mode 5-8 Amps
Space Heater 8-13 Amps
Television 1.5-4 Amps
Toaster 7-10 Amps
Vacuum (handheld) 2-6 Amps
VCR 1-2 Amps
Washer/Dryer 14-16Amps
Bill Johnson
Birmingham, Alabama

Forum Jump:

Users browsing this thread: 1 Guest(s)