DC power running AC appliances

[(unknown)]

Hey all. Living in South Florida where the power goes out for days on end after storms, I could not help but sit there sweating and wonder if I can run an 120VAC fan with 20 - 6Volt format Eveready batteries. Before I attempt to experiment, and run the risk of fire or damaging the motor, I figured I'd ask around. NOTE: Rather than use an inverter's wattage output to power an AC fan, I'd much rather free up those inverter watts to power a TV and other stuff. Also it's safer to let store bought batteries powering something while you sleep than my car battery powering an inverter powering a fan during the night.

So, I'm inquiring if I can literally hook up 20 6Volt format batteries (to equal 120 volts) to a table top fan (non-oscelating 120Volts AC - 1.2 amps - 60 Hz). Is this safe?  Would I damage the fan motor? Would I need to convert the motor itself to safely operate on DC power? Lastly, if I can hookup an AC Fan to DC power, how long would an AC fan as described run on the proposed DC power source.

Thanks!

Brian M - Wilton Manors, Florida

[drdongle]

Unless the fan is an AC/DC type ( with brushes) the answer is NO.

Why not get a 12V radiator fan from a car and use that. Simple and fool proof.

[Norm]

 Even better than a fan radiator is...





 ... a blower for car heater/ac build a shroud around squirrel cage and you have basically what

sells for $50-$60 as a shop blower.

If that's too much air just use 6 volt  to power it instead ...very quiet on 6 volts.

  When the power goes off I'm never

 lacking for 12volt fans/blowers to use out in the shop.

              ( :>) Norm.

 

[elvin1949]

 I agree with you 100% Norm.

move's more air with the same juice.

later

elvin

[crashk6]

It is indeed possible to run may household items on 120 volt dc, however there are some technical issues that must be addressed and not every device will run on dc. Your fan is likely NOT able to operate on dc... most fans use inexpensive AC induction motors. I agree with those on the board that a low voltage DC fan is likely the way to go depending on your application. Go to an RV shop they have 12volt table top fans that may fit your needs.

As for other devices that may be run on 120 DC examples include coffee pots (without fancy electronic timers)or other resistive heating devices (including incandescent light bulbs), any electronic device with a SWITCHING power supply that does NOT have a voltage doubler will also work. I have run compact fluorescent lighting with ELECTRONIC ballasts on 120 DC and they work well. You can NOT run devices that use transformers, as DC voltage is incapable of creating a magnetic field the transformer.

What you can run on 120 DC is not totally clear cut.. so if unsure have someone more familiar with power circuity look over the schematic for the device in question.

One thing to note here is that the line voltage switches in most devices can not handle  DC because they can't extinguish the arc (DC does not go to zero potential like AC) and subsequently will ether melt and be a fire hazard or just fail over a short period of time. A solution to this was mentioned by another member of this board, he connects a capacitor across the switch to keep it from arcing. I believe he said his coffee pot had been running this way for 15 (?) some odd years with no problems with the switch.

Regards,

crashK6

[nothing to lose]

"he connects a capacitor across the switch to keep it from arcing. I believe he said his coffee pot had been running this way for 15 (?) some odd years with no problems with the switch."

I wish I could keep a coffee pot working for 2 years on normal power even! Oh well..

[nothing to lose]

As for the fans, lots of DC fans of all types on the market for cheap, I would do as others mention and use cheap or free car fans with DC motors. Or buy a $10 or less DC fan from Walmart in the Auto section.

 I tested mine last night, my meter showed it to be pulling less than .5amps off a 12DC power pack. Powerpack digital display showed it only had around 30% charge, fan ran all night and most the day before slowing down with a low battery around 2 0r 3 Oclock this afternoon.

I like Computer fans myself though. Buy what you want for the price your willing to pay, less than $1 each usaully with sleeve bushings or get fancy and pay up to $10 each with double ball bearings and temp sensors to adjust speeds automaticlly. I preffer cheap ones less than $1 for most things, better ones for my valauble PC's.

They run slow at low volts, fast at high volts, easily speed controlled with a pot switch or a temp sensor in the line. I will be making more units up before long and hopefully take pics this time.

What I like to do is cut a piece of plywood or similar to fit a window or other opening. Car windows, house windows, duct work, doesn't matter just cut to fit. Then bore holes in it the size of the fans round hole you'll be using. Screw the fans down over the holes, run all wires to one area and connect together to lines for a 12v power source. For windows I cover the outside with screen to keep bugs out. Now I have a nice little homemade fan unit I can use any time anywhere, uses little power, and I can have the fans blowing in or out, or I can even reverse the way some are mounted so the top blows out the window and bottom in. I can even mount at slight angles to spread the air around like some to the left side of the room and some to the right side, top and bottom of the room too if I choose. I love these little fans for many things

 I buy most of mine from bestbyte.net  and they normally have most the important info listed for the fans like cubic feet per minute the fans move, DB noise levels, bearing types, etc...

Been awhile since I bought anything from there, I still have fans in stock, but I always got great stuff and great service from them, which is why I mention them for such things. No affiliation!

[Dreadstar]

Just do what i did build a 120mm computer fan array add as many fans as you need for the airflow i use a single 120mm fan on my desk to help when it gets hot panaflo fairly quiet moves a nice breaze and for under $10 shipped does a nice job. runs on 12vdc higher works awell and it will spin at 6vdc aswell.

check out my 20" box fan dc replacement  http://www.fieldlines.com/story/2005/8/27/42713/8716.

at almost 1000cfm makes a nice air mover that will run off any 12 volt dc source.