Another question for electronic gurus.

[Barbarin]

3,6v DC to 220v AC Inverter 40 Watt Peak power. Can be done even with poor efficiency? Of course I'm sure it can be done, but I'm thinking about a compact size, few components board.

The idea is making a flood flashlight using a 20 Watt CFL 6500 ºK E27 lamp. I'm thinking on using them as their technology has been tested during years and they have reached more tha 60 lm/Watt with good light spectrum. They are reliable ( 10 K hours) and cheap.

Thanks

 

[Photonian]

It can be done. Efficiency above 75% would be difficult to acheive.

 

[Steelwolf]

3.6V is asking a bit much. But boosting 6V or 12V to something useable by a CCFL or CFL has been done over and over. There are some kits on the market, a couple of ready made solutions (flashlights), etc.

I own a reading lamp that runs off 6V (4 AA cells) to burn a 5cm CCFL tube. Similarly in a flashlight with a 10cm tube (plus 3 LEDs and an incand). Previously had a waterproof light from Energizer (bright yellow in colour) that also ran off 6V to burn a normal short FL tube. I have read in Silicon Chip magazine about a kit that will run up to 100W of CFL from a 12V battery. And if I check my archive, I'm sure I've got a couple of webpages showing schematics for circuits to run CFL tubes off 6V and 12V sources.

But I have yet to see 3.6V inputs running a CFL. Just too inefficient to be useful, they said.

 

[jtr1962]

It can be done but it makes no sense. You'll have losses converting 3.6V to 220VAC and then further losses in the CFL ballast. In effect you're doing two voltage conversions. Also, many inverters produce a pseudo sine wave or even a square wave. This may cause problems or result in less that optimal efficiency for the CFL ballast. It would make more sense and be more efficient to simply make a driver for the CFL tube which runs from 3.6VDC. Granted, it won't be as efficient as 12VDC circuits, but I imagine with the proper components you should be able to get 80% efficiency (as opposed to the 95%+ possible with a 12VDC CFL driver circuit).

 

[Lynx_Arc]

3.6v @ 40watts is about 11AMPs that is assuming 100% efficiency, drop that to 75% and you will have to add another 4amps to about 15amps. To run at 20watts will require about 8 amps assuming 75% efficiency. If you look at all the battery powered flourescent lights you will have an idea what works and doesn't work well by the commonly available lights and their battery types/quantities used per flourescent wattages.

 

[UK Owl]

You could always pick up an emergency lighting 'brick', the ones that use a 12' 8 watt fluorescent tube. Most have a 3.6 volt D cell NiCd pack with charging circuitry (but sometimes a 4.8 volt 4 cell pack) you can pick these up in the uk for about £20. If you want one that uses a 4 pin 2D 28-Watt CFL (these nearly always have 4 cells) It will be far more expensive (approx £90 UK).

edit: I forgot to add - Both types are normally rated to run for 3 hours, but will often stretch to 4.