THE Inverter thread

Scot_Perry · #15 09-14-2005, 03:37 AM

If I remember my basic electronics correctly it's volts x amps = watts. So if your pack is 120 volt and needs 10 amps it needs a 1200 watt generator. I ran a balcar Nexus pack off one but as I remembered it choked on the fastest setting unless you have it set for max power so it doesn't auto idle. The Nexus can be set to draw 4, 8, or 16 amps so it worked fine in the 4 and 8 amps mode.
4 x 120 = 480 watts / 8 x 120 = 960 watts / 16 x 120 = 1920 so it was pushing the limit and the auto idle could not accelerate fast enough to keep pace with the instant load demand.

It was a great generator I borrowed it from a friend. I also used it for a week after a hurricane took out my power it ran 24/7 without any problems. It's also very quiet my neighbors didn't even realize I had it running in the backyard. I was not putting a high demand on it so it was just idling it revs up as demand increases.

Scot

Mitch_Miller · #16 09-14-2005, 12:03 PM

The only thing that can cause problems with this forumla is what's called Power Factor. Power Factor only applies to A/C power, not D/C. In D/C applications, VA and Watts compute to the same value (the power factor is 1, or 100%). Additionally, power factor only applies when the load (what's using the power) is not purely resistive. Lightbulbs and heaters are resistive loads. Transformers are inductive, as are switching power supplies (most PC and consumer grade power supplies are either transformer or switching based).

In these cases, it actually takes more Watts to power the device. Long explanations, that go way above my head can be found on google. One example here -> http://hyperphysics.phy-astr.gsu.edu...ic/powfac.html

To summarize ... be careful in sizing your generators when your needs are close to the maximum output of your supply.

Pablo_Villegas · #17 09-15-2005, 10:31 PM

Thank you both. Yeah, I know about the amps, my power pack needs 15 amps but, at least in AC power I can conect it to a regular 15amps outlet without a problem, you can't do that with continous light(12 amps tops), so I thought strobes handle different because of their short time of total power needed, I can also plug more than 2000W/s in a regular outlet without trigerring the braker, and with continous light you can't do it(1500 W tops). So my question is if I could plug in a 15amps power pack even if it's not at full power to a 2000 watts generator?

Thanks again

Michael_Murphy · #18 09-16-2005, 02:03 PM

[ QUOTE ]
To summarize ... be careful in sizing your generators when your needs are close to the maximum output of your supply.

[/ QUOTE ]

Mitch, can you shed any light on using AC inverters that put out substantially less power than the strobe attached to it?

For example, the Alien Bees Vagabond has a 150 watt inverter. People have been asking about using it with non-Alien Bee lights, like a 600 w/s monolight or similar. Alien Bees warns about using it with non-AB strobes in it's literature. Same question with the Innovatronix.

Is there a potential to damage the equipment by forcing it into much longer recycle times by starving it? Rob mentioned in his review that the fan in his Elinchrom monolights ground to a halt when recharging on the Innovatronix.

I haven't been willing to experiment with my own equipment [img]/images/graemlins/grin.gif[/img] I guess you would have to set up two units side by side, one power starved, then pop them again and again .....

Best,
Michael

Mitch_Miller · #19 09-16-2005, 04:02 PM

I've not experimented this way ... haven't actually used my photo equipment on portable power (just computer stuff). I've seen a lot of folks mention using power units at least as large (in watts output) to the W/s rating of your strobes. Ex: Two 800ws strobes means having at least a 1600 watt generator or inverter. That seems way overrated to me, but I have no basis disagree with someone that has had first-hand experience.

stevebrickles · #20 09-17-2005, 12:29 AM

To go full circle on this I now use and swear by HENSEL PORTY packs with Profoto heads converted to run off the packs. For it is the ultimate solution.

I started off with a VIVITAR 283 and using 2 or 3 1 meter vivitar cords could fire the flash off a lightstand and get a nice look... but with limitations on power and recycle times.

I then bought several BOWENS monobloc's made in the UK called the BOWENS TRAVELLER, these were normal 750 w/s monoblocs but they worked from 100-250v AC (so anywhere in the world) and by making or buying a switched mode power supply (Inverter) they would work from a 12v or 24v car battery.

They were fab really if heavy. Bowens also made a Traveller powerpack up tpo 3000 w/s I think, they are still kicking around ebay.co.uk now and then.

I still think the Hensel is the best, it's very underrated, it is smaller and lighter than the profoto 7b, but easier to use, a full 6 stops of power up to 1200w/s etc and the Hensel heads are very good.

you know when you make an investment in something and it makes you smile every time you use it, my lighting kit is like that.

All I can say is you quality of lighting will improve if you move upscale a bit.

s

CraigGlaspell · #21 02-15-2006, 02:26 AM

[ QUOTE ]
i didn't have that much time with my new explorer, but it seem to work fine with my profoto 600.

the box is not really fancy, but it looks sturdy and for this price it feels better than expected. the plug to connect it to my flashes is some US version of a three pronged houshold plug. innovatronix supplies adaptors, i would have prefered proper european plugs, especially as you can order the one fitting you home voltage. not the neatest solution here.

the flash pops at full power after 5-6 seconds. i tried it for about 30-40 pops, which is enough for my needs. with two flashes the recycling times goes up to 12-15 sec, both at full power. no fast paced fashion shoot here, but just about alright for architecture or similar. if you reduce the power recycling feels fast enough, i didn't bother to measure it.

i can't see any problems with consitency between flashes. but i guess my profotos are quite good at that.

the downside:
the modelling light is a bit twitchy, but one shouldn't use it anyway on batteries, as it drains too much power.
the fanns do slow down while recycling and make a funny noise, which is amplified if you use a large reflector like a beauty dish.

my verdict:

i would have never expected a battery solution for $250 that work with my profotos. shure, it is not a 7b or 2b, but it's less than a 15th of the price. it is alright and workable. it will travel with my to shoots where i don't expect that i would need it, so if i need it, i'll be happy that it is there. if i plan a shoot off the electric network, i will keep on renting a 7b.

[/ QUOTE ]

Stefan...if you are still around, how about a longterm progress report?
Have your strobes died yet from using the battery power?

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