Author Topic: A better mini-inverter for CFLs and such  (Read 28936 times)

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vtpeaknik

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A better mini-inverter for CFLs and such
« on: September 18, 2008, 11:39:00 PM »
I have built a backup power system with batteries, PV panels, and a largish (2000W) inverter.  But if I only need to run, say, one light bulb, the large inverter is very inefficient, using about 25 watts just to run itself.  (It uses much less than that while in standby mode, waiting for the freezer thermostat to demand power.)  Thus the idea of using an auxillary, smaller, inverter for lighting and other low-power uses such as a small radio.


A while back I posted about my attempt to use a very cheap inverter (the kind that is supposed to be used for charging a laptop in a car) to power an AC CFL off of a 12V battery.  Despite a claimed 70-watt rating, that inverter could not start the CFL, and lit a 4W night light only dimly.


I also found that 12V CFLs with pleasant (warm) light are hard to find and expensive relative to AC CFLs.  What to do?


With darker days approaching, I searched for other, better quality, small inverters.  I found that the standby power loss, and efficiency while running one or two CFLs, is not much different between inverters in the 100-400 watt range, so getting one that is somewhat larger than the minimum may have more advantages than disadvantages.


Example 100W model - was recently on sale at West Marine for about $16 - cheaper than many 12V CFLs.


I ordered a bigger, "400-watt" (rated 320W continuous) model made by Xantrex (same brand as larger inverters popular for off-the-grid applications), which has a power switch, a cooling fan, a digital readout of input voltage and output power, and also comes with two cables.  And all for $25 shipped!


(The pictures there are lousy, see better one, and specs, here  - and also see my photos below.)


It arrived today and seems to work well.  Standby current I measured at about 280 mA (about 3 watts).  Running one 15W CFL it is quiet and cool.  Running more CFLs, about 50W total, after a while it warmed up a bit (just noticable to a hand touching the case), and made some clicking sounds and once in a while the fan turned on for a fraction of a second.  I think the clicking sounds are from the fan "almost" turning on.  (I'm surprised the fan control circuit does not seem to have hysteresis.)












« Last Edit: September 18, 2008, 11:39:00 PM by (unknown) »

David HK

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Re: A better mini-inverter for CFLs and such
« Reply #1 on: September 19, 2008, 03:48:26 AM »
An interesting article.


But why can't you accept working with direct DC voltage CFL's rather than going through all the bother of an inverter?


Here is an extract from a set of notes I am writing about CFL's - perhaps it may be of some use to you.


"Another new discovery in the CFL line - 12 and 24 volt DC voltage CFL's


On Sunday the 31st December 2006 I made a visit to Ap Liu Street in Sham Shui Po, (Hong Kong)to update my knowledge on light bulbs. In one particular shop I was surprised to find that 12 and 24 volt DC compact fluorescent light bulbs (CFL's) were on sale. They come in two colours - warm white and cool white - and are priced at HK$80 each and made in China (HK$80 is about US$10.25). The voltage figures of 12 and 24 volts will be of interest to people who are planning to turn their home into a renewable energy palace. The shop staff explained that the Wattage was as follows:-



  1. volts DC x 1.2 Amps = 14.4 Watts
  2. volts DC x 0.6 Amps = 14.4 Watts"


I cannot find any CFL manufacturer who is planning to produce 48 volt DC CFL's at the moment (Sept 2008).


David HK

« Last Edit: September 19, 2008, 03:48:26 AM by David HK »

Tritium

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Re: A better mini-inverter for CFLs and such
« Reply #2 on: September 19, 2008, 05:35:53 AM »
I would love to find some in the USA at that price but the only ones I have found are 2 to 2.5 times more than that.


Thurmond

« Last Edit: September 19, 2008, 05:35:53 AM by Tritium »

vtpeaknik

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Re: A better mini-inverter for CFLs and such
« Reply #3 on: September 19, 2008, 08:17:05 AM »
I have looked long and hard for 12VDC CFLs in the USA and found only a few.  Some off-the-grid oriented web-shops (mostly in Canada) sell them - but usually at $18 and up, plus shipping.  I bought some cheaper ones mail-order somewhere and the "warm" light turned out to be much too "cool" for my household.  Some 12VDC CFLs are really good, but hard to find.  A local solar shop got me a 30W bulb that has very nice light - but hasn't managed to restock lower-wattage bulbs in quite a while.  AC CFLs with nice light are $2 or so each.  I've also read that typical 12VDC CFLs don't last very long, not as long as the AC ones.


So, although I do have several 12VDC CFLs and also some 12V LED lamps, I still want to be able to use some of my existing 115VAC lamps (and other small devices) off the 12VDC backup power system.  Not just in case of a power emergency, but everyday, so as to make some use of the output of my PV panels, which otherwise only top off the already full baterries on most days.  But using up the short life of expensive DC CFLs does not seem to be a net gain.  That is why it is good to have one or two small inverters that really work.

« Last Edit: September 19, 2008, 08:17:05 AM by vtpeaknik »

scottsAI

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Re: A better mini-inverter for CFLs and such
« Reply #4 on: September 19, 2008, 11:31:19 AM »
Vtpeaknik,


Couple post of mine back in December along the same lines.

http://www.fieldlines.com/story/2007/12/22/32623/837


I too bought the 40w yet only 4w inverters.

Found some real ones at 75w (ish) they got hot with 40w load after a while and shutdown.

100w pocket inverter works great for hours, as does the 300, 350w.

All drawing 120, (100w) 180ma (300w).


Large inverter in stand by draws 4-8 watts? if yours has On off switch turn it on with the freezer switch, saving even more power!


Have fun,

Scott.

« Last Edit: September 19, 2008, 11:31:19 AM by scottsAI »

scottsAI

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Re: A better mini-inverter for CFLs and such
« Reply #5 on: September 19, 2008, 11:49:01 AM »
David HK,


At even $10.25 12v DC CFL are costly.

Multi pack 120vac CFL less than $2 each.


Most of the time I want a larger CFL than the DC ones come in.

Try to find a 23watter? Or 30watts. Single bulbs are more efficient than two smaller.


From what I can find, an inverter powered CFL vs 12v DC CFL are a 1watt apart in efficiency.

An inverter/CFL cost less with more options for lights and other loads.

When the CFL fails I buy a standard CFL to replace it, not another $10+ hard to find specialty bulb.


Last search the best deal for a 12vcd CFL was $145.95 including shipping. USA


Recently added motion sensing LED lights from HFT for $5, lets me get around without tripping on things.


Have fun,

Scott.

« Last Edit: September 19, 2008, 11:49:01 AM by scottsAI »

vtpeaknik

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Re: A better mini-inverter for CFLs and such
« Reply #6 on: September 19, 2008, 11:54:24 AM »
Hi Scott.


If it's $7 on ebay for a no-brand from a no-shop, and they charge another $7 for shipping (say), I think I'd prefer the brand name model with the extra features for $25 shipped from an Amazon "partner".  Some other places sell it for a lot more (about $50 shipped), so perhaps that's a special deal that won't last?  (Not trying to push sales for that outfit - actually the packing was insufficient, arrived with the air packs collapsed and the plastic package broken open inside the cardboard box, luckily the inverter itself was intact.)


Not sure what you mean about the freezer switch.  The mini inverter I got uses 280 mA with no load, a bit worse than the ones you got.  Perhaps the digital voltage display (large LED digits, not LCD) uses a significant portion of that extra power?  (Could try and "fix" that...)  But it has an on-off switch, so can turn it "completely" off - a bit of a pain since it requires one to push and hold for a couple of seconds.  Also, not sure how "completely off" that is, will have to measure.  Much less than the 280 mA, I expect.  As for my big inverter (Prosine 2.0), it uses about 2 watts (IIRC) on no-load standby, when I have it on (usually the big 12V 250A circuit breaker is on "off"), and about 25 watts when it comes out of standby (due to sensed load, or if one chooses to disable the standby feature).


I'd love to know what 75W and 100W models worked for you, but those old ebay item postings no longer show up - can you report the make and model, and/or post a picture?  Thanks.

« Last Edit: September 19, 2008, 11:54:24 AM by vtpeaknik »

scottsAI

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Re: A better mini-inverter for CFLs and such
« Reply #7 on: September 19, 2008, 05:08:54 PM »
Vtpeaknik,

Yes, the eBay links die after 90 days.

I saw the same Xantrex 400w unit at Costco this week $19.95!-)


Pock inverter 100w Xantrex paid $11.03 including shipping.

Good name brand, just like yours.

Same unit on eBay: (not for $11:-) (Picture as requested)

http://cgi.ebay.com/XPower-Pocket-Inverter-100-by-Xantrex_W0QQitemZ380045537193QQcmdZViewItem?_trksi
d=p3286.m20.l1116


ReChecked the currents on the 100w at 180ma Iq,

The 75 watt units (no name brand) both at 0.11a Iq. Tested Unit for 1 hour with one CFL OK, with 2 CFL at 40 minutes it shutdown. Worked after cooled off. Got two units for $13 including ship. Opened it up, tiny heat sinks. Will increase their size if mounted into a light fixture.


Knowing what you need and being flexible, with a bit of searching on eBay can find it cheap, may take a few weeks... most people got to have it now once they decide to spend the money.


Would like to find a 400w without a fan, not seen it yet. Not willing to pay much for it any ways!


I though I wrote a post with all the numbers, could not find it. Wonder if its on my computer some place!


Have fun,

Scott.

« Last Edit: September 19, 2008, 05:08:54 PM by scottsAI »

solarputz

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Re: An update about CFL's and using them with inverters
« Reply #8 on: July 24, 2010, 02:04:18 PM »
Howdy everyone!

First post on here. Regarding inverters and CFL's. Off the top, using an inverter to power DC lighting is one more component that can break down. Yes, the cost of DC CFL's is expensive because in the United States, the demand is very low. In other parts of the world, demand is very high.

The most common voltage for solar outdoor lighting is 12v. Both 12v and 24v CFL's will become more popular as off grid solar power plants and portable solar lighting catches on.

The standard socket screw for 12v is E27 which is the standard Edison socket. It appears that the market is heading for an E40 socket for 24v in commercial applications.

Vtpeaknik, you are absolutely correct that quality varies among manufacturers. It is difficult find a long-life CFL at a good price. It is also difficult to find CFL's at different color temperature such as cool white at 42k. During the next year, slowly but surely, there are quality DC CFL's that will become available for long-life and with the UL safety certification plus Energy Star designation.

Hope this is helpful. :)

« Last Edit: July 24, 2010, 02:10:06 PM by solarputz »

DamonHD

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Re: A better mini-inverter for CFLs and such
« Reply #9 on: July 24, 2010, 02:22:09 PM »
The only 12V CFL I've had failed early.  Unlike the mains CFLs it needs an inverter built in to achieve sufficiently high voltage to strike the arc and that mini inverter is a source of unreliability AFAIK.

By contrast, my 12V LEDs lights are all going strong.

In fact, I'd go so far as to say that CFLs seem to me, IMHO, etc, etc, better suited to mains (110V/230V) and LEDs to lower voltages (12V/24V) and will be more reliable with less tricky control circuitry at those levels.

Rgds

Damon

Tritium

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Re: A better mini-inverter for CFLs and such
« Reply #10 on: October 14, 2010, 07:15:09 PM »
I have a harbor freight 12V CFL that is still going strong after 4 years of 24 / 7 use.

Thurmond

dnix71

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Re: A better mini-inverter for CFLs and such
« Reply #11 on: October 28, 2010, 06:56:13 PM »
http://www.sailorsams.com/lights_incnav.htm  I'm not recommending these people but if you search for boat lighting you will find a lot of options for 12v and 24v dc lighting and dimmers for same. Not necessarily cheap, but if it can withstand salt air and the constant motion, it has to be well made.

http://www.rvstuffusa.com/lighting.html  This rv supplier has 12vdc linear fluorescent lighting that looks nice, too.

http://ludens.cl/Electron/Fluolamp/fluolamp.html if you like building your own, check out this guys' 12v fluorescent lamp circuits.

frackers

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Re: A better mini-inverter for CFLs and such
« Reply #12 on: October 28, 2010, 07:33:57 PM »
The only 12V CFL I've had failed early.  Unlike the mains CFLs it needs an inverter built in to achieve sufficiently high voltage to strike the arc and that mini inverter is a source of unreliability AFAIK.

I'm surprised that you have found any CFLs without an inverter built in - all the ones I've ever seen rectify the mains to DC and then use an inverter to drive the tube.
The 12volt ones just use a different turns ratio on the transformer and draw more current at the supply voltage so use a beefier switching transistor. It wouldn't be too hard to convert an existing mains CFL to whatever input volts you want so long as you can get to the transformer primary.
Robin Down Under (Or Are You Up Over)

frackers

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Re: A better mini-inverter for CFLs and such
« Reply #13 on: October 28, 2010, 07:53:57 PM »
I'm surprised that you have found any CFLs without an inverter built in
Here is a typical circuit...
www.nxp.com/documents/application_note/AN99065.pdf
Robin Down Under (Or Are You Up Over)

divemaster1963

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Re: A better mini-inverter for CFLs and such
« Reply #14 on: October 28, 2010, 08:27:06 PM »
I have used a few 12 volt CFL's that I got from a RV center. they worked pretty good for the price. But I have gone to using 12 volt lighting from RV dealers. they use 1157 Bulbs from the automotive industry. I rebuild early model motorcycles in my shop and the light they produce works better for working on small parts. and the draw verses output allows for more lighting in my system.
I run my whole shop off solar and wind. about 1000 square feet shop. I do use a gas gen for my metal layth and metal saw. everthing else is off my system. If you still want 12 cfl units. I sugest contacting a local junkyard for dead RV's or check RV salvage dealers on the web. I got good parts off these sites.

Bruce S

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Re: A better mini-inverter for CFLs and such
« Reply #15 on: October 29, 2010, 07:59:17 AM »
I rebuild early model motorcycles in my shop and the light they produce works better for working on small parts.
This grabbed my attention :D. My neighbor and partner in rebuilding an old Suzuki frame into a recumbent style for my e-scooter testing, does the same thing.
Mostly older Kaws, Hondas and Harley's, most of which I get to help take a "test" runs  ;).
I helped him with rewiring his shop for long (2 foot) CFLs. His is full and he needed lots of light.
I talked him into going with purpose built LEDs for close up work. being able to run a super bright on a small stack of AAs helps him get around.
The AAs are charged from a couple of the 1.5 watter panels I horse traded Ghurd for, that and a dump controller works like a charm.

Makes a fair living off it.
The saying around or area is, "Don't matter what you ride, So long as you ride".

Cheers.
Bruce S
 
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JW

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Re: A better mini-inverter for CFLs and such
« Reply #16 on: October 29, 2010, 08:21:24 AM »
Here's what I use for this type of application, Ive lit 40 watt t8 bulbs with these, althou 32 watts is probaly better for them.

Quote
24 & 48 volt available on special order. See the link below for the Iota ballast selector tool

I just run mine at 12v, they work pretty good and dont waste much power. (always remember the longer of the two output wires should be run along the bulb, the shorter wire run along the bulb will cause it to swirl and flicker)

http://store.solar-electric.com/iohipo12vodc.html

Just ordered 3 of these the other day, should have them by monday, I can post some pictures of the installation if you would like.

JW

Bruce S

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Re: A better mini-inverter for CFLs and such
« Reply #17 on: October 29, 2010, 10:20:45 AM »
JW:
I've been messing around with the Triad model#C218UNVBE types.
 I get them free from work when they go bad. The "go bad" part is the internal fuse, quick fix.


These also have the ability to work off 120Vdc and will run two bulbs.

Cheers
Bruce S

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Tritium

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Re: A better mini-inverter for CFLs and such
« Reply #18 on: October 29, 2010, 06:51:23 PM »
The only 12V CFL I've had failed early.  Unlike the mains CFLs it needs an inverter built in to achieve sufficiently high voltage to strike the arc and that mini inverter is a source of unreliability AFAIK.

I'm surprised that you have found any CFLs without an inverter built in - all the ones I've ever seen rectify the mains to DC and then use an inverter to drive the tube.
The 12volt ones just use a different turns ratio on the transformer and draw more current at the supply voltage so use a beefier switching transistor. It wouldn't be too hard to convert an existing mains CFL to whatever input volts you want so long as you can get to the transformer primary.


So I should be able to run a regular US mains CFL from 120VDC as well as 120VAC?

Thurmond

Bruce S

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Re: A better mini-inverter for CFLs and such
« Reply #19 on: October 31, 2010, 12:09:48 PM »
That's what I'm working with to find out... After I return from a short trip.
I have ti build up the battery bank 1st which will be 10 banks of 12V NiCds with1.3Ah, then isolate the light from the mains, then swith it on with this "repaired" unit and see how well it works.
Will be end of November into December before I'm able to run this test though.

Cheers
Bruce S
 
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Tritium

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Re: A better mini-inverter for CFLs and such
« Reply #20 on: October 31, 2010, 02:48:17 PM »
Just tried several with a 6 panel array directly. 120VDC 5.62A array output. No controller, no batteries. An  "n:vision" 42W SKU#772-720 (home depot) flashed briefly and did not light. Still works on 120VAC though so it wasn't damaged at least. The 13W ones did not even try to light but they may not reach deep enough into the lamp socket to make contact. I will continue to experiment.

Thurmond

PaulJ

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Re: A better mini-inverter for CFLs and such
« Reply #21 on: October 31, 2010, 07:46:14 PM »
   "So I should be able to run a regular US mains CFL from 120VDC as well as 120VAC?"

   You'll need about 170Vdc (the peak voltage of a 120Vac sine wave is 170V, this is what the cfl needs).

   Here in Oz, 240Vac cfl's work fine off 340Vdc.

   Paul.

prasadbodas2000

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Re: A better mini-inverter for CFLs and such
« Reply #22 on: November 08, 2010, 05:17:02 AM »
Is there any circuit schematic published for a standard 240VAC CFL of 5-10 Watts? I have a few gone-bad lamps and I opened them up to find that from the mains there is a bridge rectifier then a fat resistor (which is generally burnt out and hence can not make out its ohm rating). So what kind of voltage these bulbs must be getting after this resistor?

After the resistor there is a set of transistors, ferrite inductors etc ending into a 4 wire fluroscent tube/bulb. I guess this must be the high frequency inverter part in it?? (sorry guys I am a person with mechanical enginerring background and not good at practical knowledge of electronics.....)

Out of 4-6 such gone-bad bulbs I could do a mix and match to assemble one working bulb.

Opera House

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Re: A better mini-inverter for CFLs and such
« Reply #23 on: November 08, 2010, 02:35:06 PM »
140V DC seems to run mine just fine.

JW

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Re: A better mini-inverter for CFLs and such
« Reply #24 on: November 08, 2010, 06:06:31 PM »
I recieved my 12 volt ballasts last monday, I had been meaning to hook them up sooner, just finished up with something that has been especially frustrating and is finally done today. (working on 2 axis hydralic tracer lathe w/30hp spindle motor)

Most likely by tomorrow, I will be able to post some pic's measuring the output voltage from the ballasts with my DVOM.(should be 600 vac)

This is for a box-truck that is using a 12 volt system in the back. The first ballast lasted over 6 months, but, do to its mounting location it could have overheated.

Im going to build 2 seperate circuits, using the 12 volt ballasts, each lighting is own 32 watt T8 bulb. Im using a configuration so that the system lacks a heavy power draw, on the 12 volt "starting battery". Typically only one lamp runs for about 30 minuites, without draining the starting battery too much. (the other bulb/circuit is used as a back up if the other doesn't light)

At this point, we are using an "intelivolt ballast using 120 to 230 vac input"(lights both 32watt bulbs at the same time) The ballast is run with a 12 volt 400watt invertor(120 vac output), but the engine must be running to keep the low voltage alarm, from activating.

Before we were using the Iota ballast and the truck did not need to be running to power a single 32watt, standard T8 bulb. (3 to 5 ft) Im using a 4 foot bulb (32watts) in this application

I figure the/some pictures would supplement this topic.

JW

JW

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Re: A better mini-inverter for CFLs and such
« Reply #25 on: November 09, 2010, 12:30:27 PM »
Here's an example of using a 400watt invertor driving a standard 120-277vac electronic ballast. As I mentioned previously we had to slap this together in a pinch, because we could not get the 12volt ballast in time. The invertor wastes quite abit of power, but it lights two 32 watt T8 (4ft) bulbs. The system does make quite abit of light though. To do the same with the 12 volt ballasts you would need 1 for each bulb, and it would be more economical than the AC invertor route.



Here's a close up of the AC ballast



Here's a picture of the 12 volt DC ballast, these are available in 24 and 48 dc volt (see link above) this is the most practical way to light the bulb (it can only light one bulb per ballast)




JW

vtpeaknik

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Re: A better mini-inverter for CFLs and such
« Reply #26 on: March 20, 2012, 02:39:13 PM »
Update: I've had that little 400W Xantrex inverter in constant use for almost 4 years now.  The inverter is constantly on, and the load on it (usually one 15W CFL) is on several hours per day.  Still works fine, and the CFL bulb hasn't needed replacement either.  It also doubles as my living-room voltage display for the solar/battery system, otherwise I have to go down to the basement to check on things.  I've also found out that this little inverter includes an over-voltage alarm: it squeals and displays "E02" if the input voltage exceeds 15V for more than a couple of seconds.