Car camping – Solar questions

Every electric appliance has specs that tell how many volts it needs to run, how many amps it will draw or how many watts it will consume. If you know two of these you can figure out the other: volts x amps = watts. A deep cycle battery will be rated for the amp hours that it will produce when fully charged. A solar panel will be rated at the number of amps or watts it will produce… though this will vary with the intensity of the sun and whether the panel is directly aimed at the sun or not… and the solar controller will step the volts down if they are too high. So working down stream: you have solar panel – controller – deep cycle battery – inverter – appliance Or Batter – appliance if it is 12 volt. Inverters themselves consume some power. Some inverters are more efficient than others and consume less power. So what you want to figure out is the amount of amp hours your appliances will draw and the work back upstream putting together a system that will provide those amp hours… or, if the system required is not feasible or practical, then working back down stream picking your appliances carefully (or limiting the hours of use)to not overload your power system. billy

If you're going to have your car with you, you can get a 12V battery charger (I use them for RC plane batteries and 12V batteries) and charge the deep cycle marine battery off that. Also bring along an AC charger so you can charge off an outlet when one is available. A 1000 watt inverter is more than enough although I don't know how much your fridge would need. I can tell you that I can run my house refrigerator off a 100 Ahn deep cycle marine battery and a 1000 Watt inverter for nearly 24 hours.

The refrigerator will be the big draw, but the rest of the stuff should charge just fine thru the cigarette lighter option. And from what I've read the newer fridges will run of the lighter plug for up to 60 hrs without having to start the vehicles emgine

Nick at popupbackpacker.com has described his solar system in detail which might help you.

There are many ways to accomplish what you are looking to do. Just depends on how frugal you need to be and what sort of vehicle you are car camping in. My car camping setup is such: Solar – Two Goal Zero Boulder 15 panels for 30 watts Solar to battery – Goal Zero Guardian Charge Controller Battery – Group 24 AGM battery in an Arkpak battery box / smart charger / inverter Fridge – Waeco CF50 The Arkpak charges via the battery by both solar and by means of the included 12v charger that connects to a regular cigar lighter. I have a dedicated 8 gauge line that runs to the back of my truck from the main battery lead to a blue sea fuse panel. I modified the 12v charger and put an anderson connector in a panel mount so that the cigar lighter wont come undone on bumpy roads. I have the power lead after the blue sea fuse box for the arkpak charger relayed with a switched power lead so that the 12v charger will only draw power when the truck is running. On solar alone with bright sunny days 30W is not enough to keep the battery topped off when running the fridge and charging other 12v devices. If I'm driving around quite a bit during the day then the 12v charger running off of the trucks electrical system + solar will keep it topped off. By my calculations I need about 90W of solar panels on the roof to keep the battery topped up with no help of the trucks electrics. If you head over to Expedition Portal and look around you will find out more than you ever wanted to know about configuring solar and 12v batteries in a vehicle based application. They have a sub forum based on all things solar and 12v power. http://www.expeditionportal.com/forum/forums/48-Power-Systems-12v-Solar-Gen

I do a lot of road trips (I haven't been to Duke or Nantucket counties yet, just the other 3,412 of them). Consider an unpowered ice chest. I've got very well insulated ones, and every hotel in the country has an ice machine. When I do stay in a hotel, I put 85% full of water soda bottles in the hotel room freezer. Otherwise, I fill a stuff sack with ice at the ice machine. Depending on the season and the ice chest, it lasts for 2-3 days. Far longer with mountain passes where I can grab some snow. Also, if you buy frozen groceries (lasagna, etc to heat on a stove or the manifold) they can serve as ice as they thaw and will keep other items cool. It is nice to have meat and cheese and dairy with you, but I'd avoid the complexity and bother of another battery and a big invertor. All your other electrical loads are very small – get a splitter for your cig lighter and start the car once a day if you're using power without driving around. A digital cig lighter voltmeter is a few bucks on eBay out of China and provides an easy check on your starter battery status.