My family is planning to spend a week camping together for our family reunion in August this year, and for at least one of the nights I'd like to set up an impromptu drive-in movie theater, projecting a movie onto a sheet or something similar hanging on the side of my trailer. The challenge is that we will be in an area that does not have RV hook-ups (so no electric grid) and it doesn't get dark enough for a projector outside until well after 9 PM so using a generator is only possible for a short time before the 10 PM "quiet time" kicks in, and the noise of a generator would be pretty distracting while watching a movie anyway, so I need to figure out if I can make it work just using the available power from my trailer battery and I'm not sure how to calculate things properly. So, here are the relevant specs: 96 Ah* capacity Interstate Group 27 deep-cycle 12 Volt RV battery Optoma ML1000P projector 300 Watt* DC/AC power inverter in the trailer A laptop will provide the video source and will send the audio directly to a pair of self-powered speakers. The laptop has a battery that can easily handle over four hours of video playback so it does not need to be plugged in while the movie is playing. The speakers last about 10 hours on a charge so they also don't need to be plugged in. * I'm pretty sure these are the right numbers but I'll have to pull the trailer out of storage and open it up to be sure. The label on the projector lists the power input as 100-240V / 1.3 A and the manual shows a Max Power of 145 Watts, but I can't find anything that says what the actual normal power draw is. I could measure it if I had a Kill-A-Watt, but I don't and I'd rather not buy one since I have _almost_ no need for one, so I'm wondering if there is a way to get a ballpark estimate with that information. I will not be using the two internal 3 Watt speakers in the projector. They will be muted and I'll use a pair of nice Bluetooth self-powered speakers instead, so the internal speaker power usage can be discounted from the total. If the necessary power for a 2 hour movie will be just slightly more than the capacity of the battery, I can also connect my tow vehicle to the battery with jumper cables battery to share its power, but I'd rather not do that if I don't need to since the car battery isn't designed for continuous deep power drains like the RV battery. Any power that is used can be recharge via generator/solar the next day. I believe that it's best to not drain an RV battery below 50% and they should never go below 20%. I'm willing to let it go a bit below 50% for a one time thing if it won't cause significant/permanent damage, but I'd like to leave a little bit of juice for the fans in the trailer if it's particularly warm outside, so let's say there's about 50 Ah available, plus maybe another 10-15 Ah? that can be added from the tow vehicle during the show if needed. Am I asking too much of the battery to run the projector for 1.5-2 hours or is this doable? If it's not possible to make an educated guess, I can pull the trailer out of storage and hook the projector up to see how long it takes to drain the battery to 50%, but I'd like to try to get an estimated run time first in case it's not possible at all. Any suggestions how to determine the power that I need, or otherwise measure things to see if it will work? The trailer is stored at my parents' house right now so I'd have to drive over, open it up, check things out, and spend the full rest of the day chatting with my Mom (it's a requirement for anyone that goes to visit )..