Light Bulbs and inverters.

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  #1  
Old 09-24-09, 10:30 AM
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Light Bulbs and inverters.

I have a question about the 120V light bulbs and inverters.
I'd like to connect a 120V light bulb to a 12V battery using an inverter. Below is what I've got but after the connection
nothing worked. The light bulb just keeps on flashing (maybe 10 times a sec) and that isn't very bright....

Here is what I have so far:
I've got a 12V 7Ah battery.
An Inverter rated at 175W that converts 12V DC to 120V AC at (continuous) current of 1.1A.
And 47W 120V light bulb that needs about 0.65A of current
(at least this is what it says on the light bulb. It is a fluorescent 5500K light bulb.)

Could someone please let me know what power of inverter
I would need for the light bulb to work? The more watts they are rated at, the more expensive they are and if I don't need that much power (apparently 175W doesn't do the trick) I'd like to keep it to the minimum (or to be safe it'll work) so the inverter doesn't draw the battery that fast. If I could have the light bulb working for about 1 hour that'd be great....
Thanks Guys
Greg.
 
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  #2  
Old 09-24-09, 11:04 AM
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Cheaper to just buy 12v light bulbs. They are Edison base just like regular light bulbs and about the same size. Try auto parts stores.
 
  #3  
Old 09-24-09, 11:30 AM
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Or RV sales places...

And I bet it has something to do with the AC waveform coming out of the inverter and the fluorescent bulb. Hmmm wait...is this a regular tube type bulb with a starter? Or a compact (CFL). The 47w is kinda odd it seems to me....that's a pretty big bulb if a CFL. Prob equiv to about a 200W incandescent?

It would probably work fine with an appropriately sized incandescent.
 
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Old 09-24-09, 12:08 PM
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Hi Guys,
This is CFL a small light bulb, not the one (long tube) with the starter. I know some guys got it to work. But they used a 300W inverter. I've seen one for about $40, so not bad, but I just don't know if it'll work for me. (other than 300W I don't know anything else - other parameters)
I need this light for a night photography and this isn't something I can buy/get at some auto parts store. I need this particular light bulb because of the light it emits. It's nicely spread, not too harsh and very "white" that basically "simulates" the moon.
I've done a lot of research abut these light bulb and night photography and this is what people recommended.
The inverter is the problem here and I simply don't know which one to get to make it work.
Any other ideas?
 
  #5  
Old 09-24-09, 12:50 PM
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OK Guys, I got it. Apparently I need an inverter that can "start" the appliance with higher voltage, like the one that can drive a TV. When TV or a light bulb starts it needs more then the continuous rated power of a the appliance and apparently the one I bought can't do the "strike". (I think that's what it called, the strike power) I already ordered one for $35 that will suits my needs. Thanks
 
  #6  
Old 09-24-09, 12:51 PM
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Ahhh good you found what you need. Not that we were much help...lol
 
  #7  
Old 09-24-09, 05:00 PM
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Just want to give you a head up with some inverter that do make square sine wave it get pretty hard on some electronic stuff as you mention CFL that will affect it.

If you have true sine wave inverter you are fine with it the CFL or TV will not affect it.


I have see it happend like that and watch your battery voltage they can drain down fast if not watching and most inverter do have low voltage cut off switch build in there so if you get below 10 or 11 volts it will shut off to prevent damage the unit.

Merci,Marc
 
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Old 09-24-09, 05:23 PM
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So I'm not sure about the sine wave...
I don't know if it is true or something else, but the inverter I got
can drive the TV so I assume it'll drive simple light bulb that for sure takes much less power than the TV.
For more interested here it is:
Amazon.com: Xantrex Technologies 851-0400 XPower Plus 400-Watt Inverter: Home Improvement

Scroll to about half of the page and you'll see a picture of it in the car with a TV connected to it.
 
  #9  
Old 09-24-09, 06:12 PM
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I did look up the spec very carefully and it did have modifed sine wave setup IMO it not too bad but some electronic load may not like it.

Merci,Marc
 
  #10  
Old 09-26-09, 01:32 AM
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Just watch out. I have blown up 3 skytronic modified inverters. You should not use flourescents with them.

Watch out for

Wire wound battery chargers (power tools etc)
Flouros
Power tools rated near the maximum (190w sander, 300w inverter = blown caps)
 
  #11  
Old 09-26-09, 11:56 AM
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Read all the comments about running fluorescent on inverters.

But as for the just the power numbers:

48 watts for the bulb is ....well, it's 48 watts.

Assuming no loss, then you would need 48 watts into the inverter to get 48 watts out. 48 watts from a 12 volt battery is 4 amps. It is a 7 amp hour battery, so it would run that bulb for 1.75 hours. Round it down some for losses.
 
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