Power Supply Problems

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    • #43593

      For several of my short films, I need to film outside where no electricity is available for miles. (In a filed, the woods, and an old dirt road.) My questions is, how can I get power to all my equipment? I’ve considered buying a transportable generator, but most are ungodly loud (and I want to avoid doing voice overs). Someone suggested run it off a car battery, but with so much equipment, i think my car would die before the shoot was wrapped up. I don’t want to buy all new equipment that’s battery-powered either. What should I do? I don’t want to spend an arm and a leg (just like every other indy film maker), but I NEED these outside shots. Does anyone have a solution?

    • #182829

      As with everything in life, there’s no such thing as a free lunch. You’ll have to spend money one way or another. That being said however, there are ways to get quiet electricity out to wherever you are.

      First, how much power will you be using? Believe me, as a filmmaker myself, I usually let my right brain creative side do all the thinking, but this is one of those times when lefty needs to come out and play. It should actually be quite easy to figure out your power needs. For example, a 300W bulb draws 300 Watts. A full computer will draw 100-300 W., depending on how powerful it is. Once you know how many watts it will take to run your equipment, you convert it to amps by dividing your total wattage by your voltage (in this case, 110 Volts). So if your gear pulls 2400 watts total, you’re going to need just about 20 amps of power to run everything.

      So you know that much, now let’s get the right gear to provide your power. My advice is if you’re not going to buy individual batteries to power all your gear, and you don’t want to use a generator (though a propane generator is quieter than a gasoline model, and they work well), your best bet is to use a DC to AC voltage converter with a car or boat battery.

      Let’s focus on the converter, since it’s probably the easiest part for now. From our example above, if you’re pulling 2400 watts, you know you need to be able to pull 20 amps. Most auto part stores, and even places like WalMart, sell DC-AC converters for cars. I bought a 30 amp black and decker model from Wal Mart that even cad clamps if I wanted to connect it directly to my car battery. It will set you back between $60 and $200 depending on what model you get.

      Your battery needs will be a bit more tricky. Now, if you’ve got a decent sized vehicle (Van/SUV/Truck), it’s more than likely that your alternator can provide as much energy as you need, but the downside to this is that you would need to keep your vehicle running, as 20 amps of continuous draw will drain a standard car battery pretty quickly. Of course, your car has 15 feet of tailpipe, a catalytic converter, and a muffler to silence most of the motor noise from the exhaust, so a good sound tech may be able to deal with that.

      But if you want complete silence on the set, then you’ll need to buy a separate battery. And I mean a BIG battery, bigger than what you’ll find in most average auto part stores. I would highly recommend that if you go this route, that you buy a super large capacity deep cycle battery. Boating stores will usually have a supply of these, or you can got directly to manufacturers (such as trojan batteries) and find a vendor from them to order from. The batteries themselves will usually carry a rating stating how long their charge will last at a given power draw. For example, this deep cycle marine battery from Trojan is rated to give you 25 amps continuously, lasting 225 minutes. So, doing the math, that means if you’re drawing 20 amps (2400 Watts) from your gear, you can expect to get about 4 hours out of this battery before it’s dead and your shooting is done. OF course, cut your draw to 10 amps, and you’ll get a full 8 hours from it.

      Altogether, you’re looking at about a $250-$300 investment for what can reasonably give you 4-8 hours of quiet electricity at a time.

      Hope that helps.

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