Hey guys, I saw a neat thing at Fry's Electronics today. It's a battery powered generator for about $300. A bit less than a similar product from Pelican (Pelican™ 9450 Remote Area Lighting System) minus the LED light though.

http://www.xantrex.com/web/id/63/p/1/pt/10/product.asp

Would be nice to use in combination with smaller powered lights. Perhaps really nice for LED lights, I'd imagine.

Great find! I think that could definitely have some uses for our type work.

Not bad.

51 amp hours should yield 3+ hours with a full load.

I wonder how long it takes to recharge.

I use an Optima marine battery in this same role. It is a sealed non-spilling 55A/H battery that I attach either a 300W or 1750W inverter depending on my purposes. There are cheap computer controlled chargers available at department stores that can charge one of these batteries overnight without overcharging. Chargers now can decrease their amperage and shut off when the battery is fully charged. This Xantrex kit looks nice but I wonder what will be the outcome when the battery needs to be replaced.

Tim, I think your estimate of 3 hours might be a bit off. According to the spec page, a 1000 watt microwave will run for .2 of an hour I think that's about 12 minutes.
I use a 1200 watt/ 3000 watt surge inverter permanently connected to my car. With a nice long extention cord voila! quiet a/c power.
Gary

I might be wrong but I was going on a normal circuit is 15 amps.

51 amp hours would yield 3+ hours given a 15 amp load right?

Sorry Tim,
Circuit capacity has nothing to do with power consumption. Watts divided by volts gives you amps - nothing for time in that equation. Amp hours is the capacity to run a certain device (in wats or amps) at a certain voltage for one hour.

So if I run 15 amps (1800 watts) worth of lights with this unit, it would start with 51 amps worth of power for the lights.

At 51 amp hours , wouldn't this translate into 3+ hours given I am only using 15 amps of the 51 per hour?

Please clarify.

Thanks

So the battery is 51Ah, which means it can supply 51A in 1 hour or 1A for 51 hours or anything in between (als long as the "A" and "h" multiply to 51). But this is at 12V (nominally).

This does not mean that it can supply that kind of amperage at 115V. The inverter is not a magical power generation device ;-)

If there is no loss in the inverter (and there will be), your 1800W of lights (which are way over the 1350 watts continuous output specs of the unit) would draw ~150A at 12V. If the circuitry could handle that it would drain in 51/150 of an hour or ~20 minutes.

You would however blow the thing (well a fuse at least I hope).

So at the maximum rating (continuous) of 1350W it will draw (more than) 1350W/12V=112.5A which give you 51Ah/112.5A=0.4533h or (less than) 27 minutes of service.

George/

Well, I'm not sure about rigging a bunch of tungsten lights to this, you'd only get a few 350w lights at most, I'd imagine. But for fluorescent lights, LED lights, production monitors, cameras, laptops, ect., this would be a great addition to your lighting equipment. It's cheap too and, because it runs on a battery, should be quieter than a gas powered generator. There's other similar products on the Xantrex website, who knows, maybe there's something better on there. I haven't had the time to research it yet.

My three Flolight 500LED lights pull 40 watts each. I could run them for a long time.

"It's cheap too and, because it runs on a battery, should be quieter than a gas powered generator."

Except for a tiny fan noise, they should be completely silent unless a low voltage alarm goes off.

"So at the maximum rating (continuous) of 1350W it will draw (more than) 1350W/12V=112.5A which give you 51Ah/112.5A=0.4533h or (less than) 27 minutes of service."

Even George's calculated estimates are too forgiving because batteries are rated at a 20 hour discharge rate. This battery will only provide 51AH if drained slowly. Assuming that something like two 650W fresnel are attached to this thing, you can probably only expect about 10-15 minutes of run time before the voltage drops too low to sustain the inverter.

"My three Flolight 500LED lights pull 40 watts each. I could run them for a long time."

Bill, since the LEDs would drain the battery at a slower rate, you should expect a few hours of service.

Battery operated fluorescent, LED, or HMI are a great idea if you only plan to run a few hundred watts. I run two 40W CFLs off one battery for hours. I wouldn't plan to run more than 300W on this Xantrex supply without shortening the life of the battery.

I am attaching a jpeg of one of my rigs.

Sorry, I was mixing 120v with 12v!

Also need to consider that the inverter won't be 100 percent efficient (nothing is). So a 1000 watt load will actually consume a bit more than 1000 watts of input power.

The mixing of 120v and 12v doesn't apply here. A load wattage is a load wattage regardless of voltage. For a given wattage, the higher the voltage, the lower the current and vise versa. Also of note is that the 120v AC spec'd here and in our wall sockets isn't the actual peak AC voltage. !20 is the RMS value (.7071 of peak voltage) and is the effective DC voltage for use in current calculations.

Marcus is dead on with the 27 minute calculation. Probably a bit less because as he noted, a 1350 watt load will draw a bit more input power than 1350 watts.

-gb-

This is quite confusing when the amps are put into the equation as the battery is a 12v DC device but anything you plug in is a 120v AC device.

I was regarding the specs as referring to the 120 AC output as opposed to the 12v DC input.

As stated, there is a lot less power when the 51 amp hours is for 12V DC.

Am I on the right track?

I'll know not to talk about electricity in public again!

Tim, you are right on the money. I really don't like the way battery manufacturers use "Amp Hours" as a measure of the storage capacity. They should use Watt hours since Watts are the measure of energy. Amps are really for measuring circuit capacity since they are a product of volts and watts.

"Marcus is dead on with the 27 minute calculation."

George did the math based on 51 Amp Hours and I cut it to a third or half due to the way high loads decrease the total output of a battery. I say no more than 15 minutes with two 650W fresnels on this battery. Switch to lower wattage lights and you will get the full draw.

BTW don't forget the lowly computer UPSs. I've used them on location before to power instruments (don't forget a hand truck - those little suckers are heavy!) - various capacities available, and when it's time for post you can stick them back under your desks. Frys or any stationery/office supply store, which makes them even more useful in the event a small genny packs up...