# power inverter for a fog machine



## Haunted Spider

The last few years I have run a fog machine on a parade float by using a generator. The generator is loud and hard to build into the float. I want to try to avoid the noise and use my vehicles engine as the generator.

I think I should be able to use the battery in the car as the power source and use a 2000w power inverter to power the machine. Has anyone ever done this and will it work? Several things on the inverter page say they don't work for motors etc like a refrigerator as they fluctuate too much and those need the pure power sine or whatever.

Would an inverter work or do I need to design in the 3500 generator again? I want to run a 1200w fog machine and a stereo, hence the 2000w inverter.

Inverter on Amazon


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## David_AVD

Most of the current draw on the fogger is the heater which is mostly resistive, so I would think that it should be ok.


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## Haunted Spider

I assume the car will recharge the battery enough or provide a consistent source of draw for the inverter as long as the vehicle is running? I am planning to directly wire it to my battery with a heavy gauge wire and use the shortest possible extension cords to the equipment to keep the draw consistent. I just can't find anything online that says you can use the inverter while driving. Maybe no one does that.


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## David_AVD

I have no idea about the vehicle charging side of it sorry.


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## corey872

That is quite a bit to ask from a vehicle charging system.

Start on the vehicle side -what size alternator does it have? Cars are typically in the 50-60 amp range, trucks typically around 100 and you can get some upgraded alternators around 150 amps or so. Volts x amps = watts, so this will give you some idea of the total input power available.. 12V x 50A = 600W on the small end and 12V x 150A = 1800W on the high end. 

Alternators are typically rated at some given RPM - likely what it might see running down the highway...several thousand engine RPM and likely 2-3x that at the alternator due to the belt / pulley arrangement. "Parade" sounds a lot like "idle speed" or just barely above to me. So you're probably lucky to get half the rated power out of the alternator.

If the alternator isn't putting at least as much power into the system as you're taking out, then the battery is draining. How much you can drain and how long depends on the size of the battery. But still most likely limited to a few dozen amps for an hour or so.

On the inverter side, I've typically seen around 70% power conversion for the cheap/dirty ones and ~50% conversion for 'true sine wave' models. Modern or high end models may do a bit better, but there is still quite a bit of loss.

So ideal side - 1800 watts from a 'big' alternator x 70% output due to idle speed x 70% inverter efficiency means you're getting just under half as usable, sustainable power - 900 watts. 

Obviously you could draw more power, but at some point the battery will run dead. You could add extra batteries to give more reserve. Use a super 'hot rod' alternator. Do some 'extreme wiring' so your heaters and other resistive elements run off of DC, while only the motors are powered by AC (thus saving the bulk of the inverter losses).

But as just a 'plug and play' solution, it would be an uphill battle.


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## trachcanman99

Haunted Spider said:


> I assume the car will recharge the battery enough or provide a consistent source of draw for the inverter as long as the vehicle is running? I am planning to directly wire it to my battery with a heavy gauge wire and use the shortest possible extension cords to the equipment to keep the draw consistent. I just can't find anything online that says you can use the inverter while driving. Maybe no one does that.


You can't assume the alternator on your car will provide enough current to both the car and inverter. you may have to add a larger alternator or better choice would be add a second alternator to run just the inverter. better choice would be to use a 12VDC stereo to reduce inverter load. inverters are very inefficient you feed 12VDC at high amperage in to get 120VAC with low amperage out. check both the input and output power requirements before hooking up your alternator. consider replacing the generator muffler with a better muffler or run the existing one into a container of water to muffle the sound, just make sure the placement doesn't allow water to flow back up the muffler.


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## BobbyA

You will be much better off using a quiet generator. 
To run your 1200W fogger, you need to draw too much current >100 Amps every time it heats.


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## Batbuddy

I concure with BobbyA. However I always like to push tings and see what you can do. In my haunt the last few years we had a ride which was a coffin that you got in and it drove around on a track. Granted we were not pulling 1200 watts, but we did have a 3/4 HP AC motor going all night on two deep cycle batteries and a Harbor Freight 3000 watt (peak) Inverter. So It can be done, but depending on the Alternator as previously mentioned having the buffer of several batteries can make it work easily.


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## Haunted Spider

Update on this as I thought it was at least worth a shot to try. 

I bought a 2000W inverter on amazon. I got the KRIËGER 2000 Watt 12V Power Inverter. It has an LCD display showing watts used. 

It came with 2 gauge cables but only 3 feet long. When it arrived, I hooked up the fog machine. My fog storm actually only pulls 875 watts when heating up. The stereo adds another 65 so I end up at 950 max pull. The inverter worked and both powered up. Once heated up, it drops to 75 watts with the fog machine still on and pump running to shoot fog, as well as the music playing.

I then added longer cables so I could get the inverter in my truck and not on the hood. I first used energizer 30 foot quick disconnect jumper cables. Even though they were 1 gauge, they were copper coated aluminum and the voltage dropped from 14 when the engine was running at the battery to 10.2 at the inverter and it would trip out. 

I then purchased solid copper 2 gauge 8 foot cables from amazon that were USA made. Those did the trick and even with the pull of 950 watts, it didn't trip out. 

I ran the truck for an hour with both on testing the battery before and after and went from 12.7 v to 12.5 v, hardly a drop at all. The inverter is listed as 90% efficient, although I imagine that is a bit overstated. 

But it did work. I ran one parade a week ago and have another this weekend. No loud generator, just some cables coming out of my truck and into the cab.


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## David_AVD

Sounds like a good result !  (apart from the crappy CCA cables)


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## corey872

Sounds good - thanks for the report back! That 90% efficient is pretty high... but even if it's in the 80's, much higher than the older inverters I have. Guess power switching gear has developed quite a bit in the last dozen years or so!

On the location - obviously many factors to consider, but as you've already found out, keeping the high current DC run as short as possible and/or using big wire is the key. You can probably run the AC output quite far with minimal voltage drop.


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## Haunted Spider

yeah, I run about 25 feet of AC cable to the float and fog machine. The DC power drop is the issue over distance for sure. Here is to hoping my parade tomorrow goes off without a hitch.


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## Zoolando

The key to making this work is not on the inverter nor the amount of watts being used. It's amperage, and can be easily worked out by simply adding another battery or two. The inverter will tap out because its not getting enough amps in the scenario you talked about. most floats nowadays got rid of the old generators, and use inverters powered by battery banks. The real debate on this topic is actually whether to to run the system in series or parallel... And yes... make sure to use very heavy gauge cable between inverter and batteries. I run 3 deep cycle heavy duty batteries in parallel to consistently power 1,200 watts of sound, an ac air compressor kicking in and out, solenoids kicking in and out and about 200 feet of led rope light. 2 batteries will do the job but the inverter would hum and tap out. the compressor draws serious amps so a 3 battery system was necessary.


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