Anker, a distributor of VERY popular USB power packs for mobile devices, sells their PowerHouse device which stores 400 watt-hours of power.  It includes one 3-prong AC outlet, four USB outputs, and one 12V output. That would give you enough juice to power your projector for over two hours. It cost $400. Personally, I’m a big fan of Anker products.

https://www.anker.com/deals/powerhouse2

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There is also the Goal Zero Yeti 150 Portable Power Station. It’s similar to the Anker but could power your projector for just one hour at most.  It sells for $230.

http://www.goalzero.com/p/164/goal-zero-yeti-150-portable-power-station

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If you want to go cheap, Harbor Freight sells a 700-watt 2-stroke generator for $110.  Add a 50’-100’ extension cord to keep the noise away from your show.

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The cheapest overall is probably a 12-volt battery and a power inverter. A 300W inverter is under $25.  Add a new battery and a trickle charger and you can put it together for less than $100. You might be able to get by with a motorcycle or lawn tractor battery for portability, but do the math first to size the battery to your application. Be sure to account for losses in the inverter as they are not 100% efficient.

Lowes has several car jump starters with inverters built in. For example,

https://m.lowes.com/pd/Schumacher-Electric-1-200-Amp-Car-Battery-Jump-Starter/50223897

I have a CPAP machine that’s about 200 watts, and I use this during power outages. It keeps going for at least 2 full nights. It’s made to be left plugged in to the wall charging, so it’s always ready to use. 

I have a big deep-cycle marine battery I got from Tractor Supply.  I use it with an inverter to supply 110 VAC power to devices when I’m in the field.

WARNING:  All cheap inverters (that I know of) do NOT produce sine wave output, and some devices require it.  Some inverters produce modified sine wave or ”stepped approximation” sine wave power, which may or may not work with your hardware.  It would be wise to check with your projector manufacturer first.

Does your projector operate on AC or DC?  If DC, you can use an inexpensive switched-mode buck converter (to step voltage down) or boost converter (to step voltage up) to very efficiently convert battery voltage to the voltage required by your projector.

Cheers,

NV1T (ham radio op, retired EE)

I looked at the back panel.   It is a DC input.   By skipping the inverter, and the factory power supply, building a DC supply for it by finding a battery at the right voltage and adding the correct plug would reduce the losses of conversion and get you a lot more time on the same battery.

I looked at the back panel.   It is a DC input.   By skipping the inverter, and the factory power supply, building a DC supply for it by finding a battery at the right voltage and adding the correct plug would reduce the losses of conversion and get you a lot more time on the same battery.