6 watt cfl power draw

 Hi all,

     Hooked up two, 3 watt 12v cfl's.  Should be a 6 watt draw, or 0.5
amps (give or take a hair) @ 12 volts.  I put a dvm in series (on
Amps) and low and behold their drawing 1.05 amps  @ 12 volts, or 12.6
watts.  Double checked with a clamp on ammeter.  Is there somthing I
still don't understand?
...........Rob

 

     Your math sure looks right.  Are you using an analog or digital meter?  If
digital, try to get your hands on an analog meter to see if you get a different
answer.

  Where are you buying 3-watt CFLs?  The only ones I have ever seen are 12 watt.

  Are you happy with their light output?

Vaughn

 wrote:

watt.

Hi Vaughn,
     I'll try an analog meter and see. The math did seem fairly
basic.  Was using the dvm to 'fine tune' the C-12

and thought I'd see what the meter said.

 Originaly I tryed using a couple of 20w bulbs,  it looked like I was
shooting a movie, Amazingly bright.

I got the 3 watt'ers from a place in Kitchener Ontario.(npp.ca). He
had a 7watt cfls (only 1 though).  The 3 watts

are nice.  (And there was 2 of them to buy).  Light to see by, but not
too much.  A little more than accent lighting?

Very happy with them, and even at 12.6 watts still frugal on the
batterys.

    The box is marked "Glenergy" (Made in China for Glenergy Inc). 3
Watts 4200K.

http://glenergy.ca/   Has them under products, cfl bulbs/fixtures.

..........Rob

 On Tue, 28 Aug 2007 18:21:42 -0700, "...........Rob"


different

watt.

Your current may not be a clean DC .
If you have connections to a local AM radio station or a surplus
store, try to get a meter  use to measure r. f.  current. They measure
RMS and are  usually very accurate. Also very delicate . Don't
overload it.

john

 
This is what's called "power factor".

In a straght resistance load, such as an incandecent
lamp or a toaster... the Volts * Amps = Watts formula
is right on.

However, in inductance loads or ones with other
funky waveforms, there's "power factor". This is
one of those things that makes my head hurt to
understand, but basically it means that
your 1 amp at 120 volts does NOT give
you 120 watts, but will give you 120 * power factor.

CFLs, at least the older ones, may be as low
as fifty percent PFs. (Newer ones are getting better).

Same thing with older traditional ballasts, and
electric motors, and compueter power supplies.

The utility electric meter is supposed to (in standard
residnetial installations) measure the wattage rather
than the volt-amps, so you're getting charged for
the lower number.

I've seen conflicting answers as to how and what
low power factor leads to when specing out designs
for small generators.

Note that the highly popular Kil-A-Watt through-plug
meter gives you readings of watts, volt-amps,
power factor, (and some other stuff). So if you
measure a CFL you'll see that 50 percent PF listing.




--
_____________________________________________________
Knowledge may be power, but communications is the key
             dannyb@panix.com
[to foil spammers, my address has been double rot-13 encoded]