Now I'm playing with power -- portable power! (Please?)

August 7, 2011 7:03 PM

How can I portably power my old slide projector on the go?

Hi Ask MeFi! This is something that I've been wanting to do for years: I have an old Kodak Ektagraphic AF-2 slide projector that I would like to provide power to portably without having to actively plug into an indoor power outlet. It has a standard 3-prong U.S. power cord, and if it's helpful at all, the power descriptions listed on the bottom of the projector are:

"120 volts ---- 50 Hz -------------- 400 watts
300 W lamp max ---------------- Use ELH lamp"

Ideally, I'm looking for:
1. A device that can have power stored up that can I can plug my projector into for a half hour or longer without the power running out
2. Something that doesn't produce toxic fumes like a generator
3. Something that doesn't tie me to my car and its cigarette lighter plug (though if nothing else is possible, a car-based power source is the last resort)
4. Something affordably priced (sub-$100 if at all possible)

I've seen plenty of devices that convert a car lighter plug into a standard 3-prong plug power source, and a few power strips that provide backup power for a half-hour-ish in case of outages, but I'm not sure if they're what I'm looking for, or if so, what brands are the most reliable. If anyone could give me advice on any of this (even if it only covers one or two of the "ideal" list), I'd be immensely grateful. Thank you!

posted by stleric to Technology (6 answers total)

That's a heck of a lot of power. Assume 80% inverter efficiency and call it 500W; 30 minutes of 500W equals 250 Ah. A 22 Ah sealed lead acid gel cell costs about $50 and weighs around 17 pounds, so a dozen of those would weigh over 200 pounds and set you back about $600, not including the cost of the inverter.
posted by Rhomboid at 7:51 PM on August 7, 2011

Mercy! I figured that it must be pretty wasteful power-wise, but maybe a car adaptor might be a better idea after all (if that's even possible).
posted by stleric at 8:16 PM on August 7, 2011

400 W is pushing it for a car inverter. Take a look at some custom car audio suppliers; people might use this kind of thing to power big-ass subwoofers.
posted by mr_roboto at 8:51 PM on August 7, 2011

Not only is 400 W pushing it for a car inverter, but you're still talking about roughly forty amps or so from the car- that;ll drain your battery very quickly, and you can't draw that kind of current from a car ciggy lighter socket.

Backup UPS stuff- I have one that's capable of 1100W continuous, but at that power level it'll drain its internal batteries in about five minutes.

A looo-o-ooong extension cord, now.....
posted by drhydro at 9:03 PM on August 7, 2011

You might consider just buying a projector meant for portability. For example, this will give you 200 lumen at 81W which is considerably easier to achieve with a portable battery. From what I can google, that Ektagraphic delivered between 500 and 1300 lumens depending on whether a long-life bulb was used or not, so this would definitely be a step down in terms of brightness, and you'd have to scan your slides, and it's only 800x600, and it's $330 plus the cost of a battery setup, so it's not the greatest solution in the world. Of course, if you need less than 200 lumen then there are even smaller portable models that use less power.
posted by Rhomboid at 9:51 PM on August 7, 2011

Powering the Ektagraphic portably seems prohibitively inconvenient and/or expensive, so it looks like a more portable projector is probably the way to go in the long run. Until I get a better camera though, I need every last lumen I can get, so drhydro may be on to something with the extension cord. Thanks for the answers, everybody!
posted by stleric at 1:54 PM on August 15, 2011