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Intermittently Powering Tungsten Lights with Vagabond?
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Author:  TimHenrion [ Fri May 27, 2011 12:03 pm ]
Post subject:  Intermittently Powering Tungsten Lights with Vagabond?
I know that this is probably sacrilege in a Paul C Buff forum but I'm looking for a portable 120VAC solution for powering quartz halogen tungsten lights in places with no power.

Specifics:
I've got a single quartz halogen tungsten light, 500-1000W (variable) watts that I need to power intermittently for about 10-15 seconds every minute for 5 minutes at a shot followed by a 10 minute rest. I only need a small number of these cycles (less than 10) per charge although more would be nice.

The Vagabond II/Vagabond Mini specs don't seem to talk about how they deal with continuous draw over a 15 second period (and how long they'll last in this situation). Voltage variation over the "on period" isn't a problem as I'm using TTL metering. It would be nice, however, if whatever voltage that comes out of the pack under constant load is constant to minimize fluctuations over the 15 second period.

Any chance that a Vagabond II or (ideally) Vagabond Mini would work in this situation?
Author:  Luap [ Fri May 27, 2011 2:49 pm ]
Post subject:  Re: Intermittently Powering Tungsten Lights with Vagabond?
VML will not power over 250W even on a short term basis. A 500-1000W lamp will current limit and you'll only get 250W out of it . . . then the inverter will overheat and shut down pretty quickly. A VII will probably run up to about 600-700W lamp on the basis you describe . . . but not for long.
Author:  Technical Support [ Fri May 27, 2011 4:26 pm ]
Post subject:  Re: Intermittently Powering Tungsten Lights with Vagabond?
Is there an inherent reason a continuous light source needs a pure sine wave inverter? If not, then you should be able to get a 1000W inverter relatively inexpensively. Depending on your definition of portability, you can get a SLA battery to fit your needs.
Author:  Joseph S. Wisniewski [ Sat May 28, 2011 3:22 pm ]
Post subject:  Re: Intermittently Powering Tungsten Lights with Vagabond?
Technical Support wrote:
Is there an inherent reason a continuous light source needs a pure sine wave inverter?

Rarely. A thin, lightly supported filament will physically oscillate at twice the line frequency, and a square wave inverter will increase the physical stress, shortening bulb life. (An infrared flood will blow to pieces).

For just about anything that the OP is going to deploy as his light, the square wave inverter and "small" SLA should be fine.
Author:  Luap [ Sat May 28, 2011 6:15 pm ]
Post subject:  Re: Intermittently Powering Tungsten Lights with Vagabond?
You have to remember 960W at 120V is 8A. At the battery (assuming 100% efficiency) that come our 80A at 12VDC. You can figure close to 100A from the battery. This means huge cables and a significant battery. A smallish battery will have too much internal resistance, which will reduce the efficiency, limit the amount of on time and waste a substantial portion of the battery capacity in heating the battery instead of lighting the light.

You can get 12V track lights up to about 65-75W. Ten of these run directly from the battery would eliminate the inverter entirely. If they still make old style non-sealed beam auto headlight bulbs this might be worth looking into. Low voltage bulbs produce higher efficiency and longer life than 120V bulbs because they have thicker filaments.
Author:  TimHenrion [ Mon May 30, 2011 10:48 am ]
Post subject:  Re: Intermittently Powering Tungsten Lights with Vagabond?
Thanks to Paul and everyone else who responded.
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