Power supply in the field

I am going to be going to a very remote very dark sky and will be bringing my imaging system (C8 w CCD camera and Laptop) with me - I will not have access to a car battery (going by boat) and the Nicad battery in my laptop wont do and I will need a power source for my peltier cooler in my camera - Thus I need a battery type, compact power source which I can plug a laptop and peltier cooler into and have it run for at least 4 hours. Does anyone have any ideas? I am taking all this on several flights so it can't be a car battery...

Also cheap is good.

THanks - Brooks

Batteries, by their nature, are heavy. Generally, the heavier a battery, the more power it can supply. Taking batteries along on the airplane is probably not your best strategy. Ship them separately, or buy them locally (or as close to local as you can manage).

If you can recharge after 4 hours of use, then you can probably run all that equipment on something like 50 amp hours and have adequate safety margins (for both time and power). But the right answer here is to check each piece of equipment you plan to use, and find out how much juice it uses per hour, and then buy a battery than can reliably deliver double that amount (I usually like to have triple for emergencies and unforseen situations, like slewing much more than i had anticipated, but in your circumstances a 2x power fudge factor is probably a good compromise). Until you know how much power _your_ specific equipment uses, you are taking chances.

Ron Wodaski

If you're talking about a plug-in power supply, it'll cost you quite a lot of money to find or build one that can supply the currents that a peltier draws and power your other equipment on top of that. It will also not be compact or light.

How powerful is this peltier?

If you're looking for a battery you can get a gel-cell lead acid battery. It's safe for mailing and shipping, but it's still going to be very heavy and quite large as well. Alternately, you could consider some sort of NiMH battery pack. NiMH batteries can store curiously large amounts of power given their size and weight, but you'll need a special charger for such a battery pack and again it will be neither light nor small for your application.

Why not use the boat battery, or is this a sail boat or something?

Brooks,

How much current "in amps" does this rig require ? The laptop will need about 2-5 amps. The camera, I don't know but to calculate the battery size needed is easy with this formula. Amps X hours needed + 20 percent "if using an inverter". Thus, amps=1 X 10 hours of use=10 + 20%= 12 amp hours. As you can see it will require a large battery of around 40 amp hours "4 amps for 10 hrs or 8 amps for five hours" and heavy. What about recharge ? If your still there in daylight you could use a solar panel of about 50 watts otherwise some type of generator would be required. A small 300 watt generator would weigh no more than a battery but would still need gas and oil and the noise will drive you nuts. But considering what you need a generator may be the best idea. It really all depends on how much current you need. Try not to use an inverter to reduce wasted energy. Also, some batteries cannot maintain high discharges for long periods of time "ie car starter batteries". Wiring is also a consideration for high current low voltage applications. I think the generator wins !! I don't think Nicads and cadmium batteries will fulfill your requirements. Good luck........!!

in such a situation, where power is extrememly hard to come by, perhaps a 35mm film camera would be a refreshing change...