Power Inverters

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DanJetta
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Power Inverters

Postby DanJetta » Sun Jun 07, 2015 5:27 pm

Hey guys,

Any tips on running an inverter off of my battery? How big before I blow something up? Pep boys sells a 3000W inverter but, somehow, that just screams "car fire" to me.

We're filming a commercial and need to mount a bunch of lights all over my Pathfinder. Last time we strapped a little 3K Watt Honda generator to the roof but it presented some audio issues.


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Lord Farquaad
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Location: South Africa

Postby Lord Farquaad » Fri Jun 26, 2015 7:28 am

I don't think the size of the inverter would be the problem. The inverter will draw what it can from the battery. Your problem will be the capacity of the battery to run the AC equipment connected to the inverter. You will need to calculate what size inverter you need, and what capacity batteries you need based on the wattage of the lights you want to run for how long. AC lights, unless LED, would take a fair bit of battery and inverter.

Why not get 12VDC LED lights and run that straight off the battery, or better yet, off an auxiliary battery? Similar to LED light bars that is so popular now. That will eliminate losses in the inverter and you can get away with a smaller size battery.

Are you using the kit from the previous shoot, or is it possible to buy new?

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SETI20
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Location: Ontario, Canada

Postby SETI20 » Fri Jun 26, 2015 8:25 am

I don't think there is any inverter/battery combo out there that can handle pro quality continuous video lighting.
I have pretty high-end photography strobes with power packs, and just running the modelling lights on them would drain them in under 20 minutes.

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Lord Farquaad
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Postby Lord Farquaad » Fri Jun 26, 2015 1:40 pm

SETI20 wrote:I don't think there is any inverter/battery combo out there that can handle pro quality continuous video lighting.
I have pretty high-end photography strobes with power packs, and just running the modelling lights on them would drain them in under 20 minutes.
I would beg to differ. Problem is, you need a trailer to tow it around. It is all about the batteries and they don't weigh in light.

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SETI20
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Location: Ontario, Canada

Postby SETI20 » Mon Jun 29, 2015 2:35 pm

Alright, lol. I am fairly sure a converted power source from a Tesla would work as well. But I'm not entirely sure if either of these are practical compared to running a quiet generator.

DanJetta
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Postby DanJetta » Mon Jun 29, 2015 6:57 pm

Great info, thanks guys!

Sounds like the goal is to pull less power than the alternator can supply (to keep from draining the battery).

We ended up running two 12" LED panels off of a 400 Watt inverter and two 800 Watt HMI Pars off of a Honda eu2000 "put-put" generator. The generator wasn't that loud but it would resonate through the body of the car when mounted on the car (even with sound blankets as a barrier). To combat this, we had a Production Assistant stand on the back bumper holding the generator away from the body of the car.

We can't use standard LEDs, unfortunately. Film lights are balanced to a very specific color temperature. Standard LEDs tend to have low CRI (color renditioning index) ratings and color spikes that cause problems on camera.

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Lord Farquaad
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Location: South Africa

Postby Lord Farquaad » Mon Jun 29, 2015 7:40 pm

It would be easy to calculate the size of the inverter and amount of batteries you need. All you need for this is the amp rating of all the equipment you want to run at the same time and for how long. Based on that you can determine the wattage of the inverter and the amount of batteries.

We have a thing called "Loadshedding"here by us. Basically our power utility can not supply enough power for everyone in the country during peak times, so some people get cut off to keep supply and demand balanced. It is on a rotational basis. So, if you want the lights to be on during your turn, you have to provide your own power. We are pretty good at calculating what we need to keep the lights on by now. :D

You get me the info on all your equipment and I will give you the answer, unless you go Google it. The info/formulas is out there. You might also know an electrical guy that can calculate it for you. Hope it is a one night stand thing, because if you want to solar charge it for a second night, that is another story. But you could then use your generator with a standard charger, which would be cheaper.

suffolkpete
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Joined: Mon Mar 09, 2020 8:39 am

Postby suffolkpete » Mon Mar 09, 2020 8:42 am

Keep the cables between your inverter and batteries as short as possible. This will help your batteries perform their best and keep the unit’s signal clean. The cables that come with the inverter are “rated†or good for up to six ft. If you plan on going over six ft., drop down to a larger gauge cable. Please call us if you are still unsure. This is pretty important stuff that should NOT be overlooked. If the cables between your battery and inverter get hot while under heavy load, then you should use heavier cables.

OregonPath
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Joined: Tue Jan 30, 2018 7:56 pm

Postby OregonPath » Thu Mar 26, 2020 7:18 am

Speaking from a practical point of view, yes it works. I use saws, vacuums, etc.

Keep the motor running if possible.


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