sardonyx247 wrote:We found the best genny out there WITHOUT spending $$$$$$$, use 12volt to 120volt invertors and run your car, yes that is right your car, cars now are quite and you can barely hear them.

Riffing a bit on this ...

For small loads -- things you could charge with a small solar system like a few strings of LED lights and some battery chargers -- this setup would work great. But the car battery is only good for little things like this. Its primary function is as a starting battery and, as such, would be ruined by getting discharged to 50% a few times in a week. (E.g. a small car might have a 50 amp-hour battery at 12 volts, so that's 600 watt-hours of energy, but don't want to discharge it more than 15% or so, so you can only use 90 watt-hours of energy before starting the car and charging it back up. Thus, 5 watts of LED lights for 10 hours would use 50 watt-hours at night and 1.5 watts of battery chargers for 24 hours would use 36 watt-hours, and that's about all it can muster.)

To move up one level to more power, say for a modest sound system (200 watts peak; 50 watts average) I'd recommend buying a deep-cycle battery. When you get to the Playa, disconnect the car's battery and insert the deep-cycle battery in its place. A big 180 amp-hour deep-cycle battery can be run down to 50% capacity, so that's 90 amp-hours or 1,080 watt-hours. You could run 45 watts 24 hours a day with that and charge it once a day. (Or, if you do the math, you can run 6 watts for the whole week straight — or 12 watts each night — and never need to recharge the battery at all.)

But Captain Goddammit is right: you're only going to get a few amps at idle ... maybe 15 amps if you're lucky, so making up that 90 amp-hours is going to take 4 hours of idling the car. In one of the hottest places on earth. Not a wise idea.

But if you went with the big deep-cycle and got a solar panel barely adequate for your needs. (Remember that you only get 6 hours equivalent of bright noon sun: one true hour at noon, but less power each hour before or after noon.) So you go with a 100 watt solar panel and get 600 watt-hours each day. Now you only need to make up the remaining 400 watt-hours with the car (which at 15 amps at 12 volts produces 180 watts) which is still 2 hours of idling. If you cut back your consumption more, you could get away with most days being completely charged by the solar panel and only use the car if you need a boost.

Captain Goddammit wrote:If you have a little fuel-injected 4 cylinder car, it'll idle a long time, but if you use a truck or whatever with a big V8 you'll be amazed at how much fuel it will idle through! Test at home, get some data and bring enough.

I drove a friend of mine's Honda Fit for a bit. It has one of those gas mileage gauges (which is now computerized and relatively accurate compared to a vacuum gauge marked out in MPG). On a long side street, I dropped the car in neutral (thus, the engine was idling) and coasted down until the gauge read 40 miles per gallon; that was at about 10 miles per hour, and (40 miles/gallon)/(10 miles/hour) maths out to 4 hours/gallon.