How do you measure electrical power consumption?
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How do you measure electrical power consumption?
I want to bring a fan to cool my tent on camping trips. I found a fan that can be plugged into a vehicle's cigarette lighter but I wasn't very impressed with the product and decided to check out household fans instead because I have a portable booster pack that can power small gadgets.
I'd like to know how long I could expect the fan to run off the battery pack between charges.
On the back of the first fan I'm considering is a sticker that says the following.
Power Supply: 120 VAC 60 Hz/
Power Consumption: 25W
A larger 20" box fan has the following
120/240VAC-60HZ-23AMPS
120/208VAC-60HZ-21AMPS
My power supply is the XPower Powerpack 400 Plus which according to specs has a "Sealed, non-spillable 20 amp-hour AGM battery".
I'd like to know how long I could expect the fan to run off the battery pack between charges.
On the back of the first fan I'm considering is a sticker that says the following.
Power Supply: 120 VAC 60 Hz/
Power Consumption: 25W
A larger 20" box fan has the following
120/240VAC-60HZ-23AMPS
120/208VAC-60HZ-21AMPS
My power supply is the XPower Powerpack 400 Plus which according to specs has a "Sealed, non-spillable 20 amp-hour AGM battery".
Posting Guru
Joined: Sep 2004
Posts: 1,616
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From: Sapulpa OK
Well, volts times amps = watts So in your first example 120 / 25 =4.8 amps. There are some other factors to consider but this will give you a rough estimate.
In your second example120 X 23 =2760 Watts That's almost 3 kilowatts
I can't tell you how long your battery pack will last, I am not an electrical engineer. maybe someone else can chime in.
In your second example120 X 23 =2760 Watts That's almost 3 kilowatts
I can't tell you how long your battery pack will last, I am not an electrical engineer. maybe someone else can chime in.
Cargo Master
Joined: Apr 2003
Posts: 3,476
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From: Frequently frozen MN
If you've got the same XPower Powerpack 400 Plus that Amazon is selling, it should run the small fan for 7 to 8 hours. ( Amazon has the owner's manual available as a pdf -- might be worth checking.)
You need better info on your 20" fan -- no way that any household fan takes power like that. They MIGHT have printed VA (volts * amps). They sometimes use that instead of watts for reasons that I don't really know. It's either regulatory, or it could be a slightly different measurement. In any event, VA should be pretty much watts -- worst case around 23 watts. So, a little over 6 hours for that one.
20 amp hours means pretty much that -- 20 amps for an hour, a amp for 20 hours, etc -- at 12 v. It actually is generally less than that because of how it's spec'd. 20 amps at 12v will be something less than 2 amp hours at 120 v ( it's not 100% efficient). But, your little fan only takes about 0.2 amp at 120 v -- so it works out.
hope that helps,
hj
You need better info on your 20" fan -- no way that any household fan takes power like that. They MIGHT have printed VA (volts * amps). They sometimes use that instead of watts for reasons that I don't really know. It's either regulatory, or it could be a slightly different measurement. In any event, VA should be pretty much watts -- worst case around 23 watts. So, a little over 6 hours for that one.
20 amp hours means pretty much that -- 20 amps for an hour, a amp for 20 hours, etc -- at 12 v. It actually is generally less than that because of how it's spec'd. 20 amps at 12v will be something less than 2 amp hours at 120 v ( it's not 100% efficient). But, your little fan only takes about 0.2 amp at 120 v -- so it works out.
hope that helps,
hj
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My bad. The second set of numbers was from a clothes dryer we messed up on a moving job. Should probably order that new door.
I think I'll get the smaller fan anyway since it's a lot less noisy.
Part two of my plan is to build a homemade air conditioner using a fan, copper tubing, a cooler filled with ice water, and a small aquarium pump to circulate cold water through the copper tubing, and across the surface of the fan. I'm copying some ideas I found on the internet. But because I'm working with a limited power supply, I want to make mine as efficient as possible.
I'm convinced I can get my wife to go camping again. I just have to figure out a way to bring along every imaginable convenience.
I think I'll get the smaller fan anyway since it's a lot less noisy.
Part two of my plan is to build a homemade air conditioner using a fan, copper tubing, a cooler filled with ice water, and a small aquarium pump to circulate cold water through the copper tubing, and across the surface of the fan. I'm copying some ideas I found on the internet. But because I'm working with a limited power supply, I want to make mine as efficient as possible.
I'm convinced I can get my wife to go camping again. I just have to figure out a way to bring along every imaginable convenience.
Sit. Stay.
Joined: Oct 2001
Posts: 18,308
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From: Washington State
Keep in mind that you can only (should only) really use 1/2 of the rated amps hours. Meaning: you should only discharge your battery to half.
Your battery is a 20 amp hour?? That's one tiny *** battery. That means you got 10 amp hours that you can use. Running a 12v appliance on it means you can run something that is 120 watts for an hour. In your example, you can run your 25W fan continuously for a little more than 4 hours.
Get a bigger deep cycle battery from Wal-Mart that is at least 80amp hours. Buy at least an 600W inverter.
Recharge it with your vehicle (I run dual batteries) or a solar panel or small wind mill. The last two will require a charge controller...and deeper pockets.
Your battery is a 20 amp hour?? That's one tiny *** battery. That means you got 10 amp hours that you can use. Running a 12v appliance on it means you can run something that is 120 watts for an hour. In your example, you can run your 25W fan continuously for a little more than 4 hours.
Get a bigger deep cycle battery from Wal-Mart that is at least 80amp hours. Buy at least an 600W inverter.
Recharge it with your vehicle (I run dual batteries) or a solar panel or small wind mill. The last two will require a charge controller...and deeper pockets.
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