Post
by Dusmir » Sat Aug 03, 2013 12:13 pm
If you want to run your cooler off of solar, here are a few things to consider BEFORE you get your parts.
Don't run without a battery in the loop. Solar panel voltages and charge rates swing wildly with the amount of sun exposure.
You can use a very small, light battery, like in a UPS backup/surge suppressor, (check computer stores) they are usually about 7 amp hours. (which means they will run things a couple hours at most, not 7.) It is the reserve capacity that isn't as great, not the voltage. If the panel isn't charging a while, it won't run things as long. Figjam's big deep cycle battery will run a week with no charge, the little backup battery will run maybe 2 hours without a charge.
Don't expect a 5 or 10 watt panel to run anything very well. These are mainly for maintaining fully charged batteries with no load on them, and will not charge a dead battery. If your panel puts out .2 amps in full sun, and you are pulling 1.5 to 2 amps with your pump and fan, you will have a dead battery!
Any panel 15 watts and over, will need a charge regulator. They can put out up to 18 volts un-regulated, and can destroy a 12 volt accessory.
ALL items hooked to the system need to be rated at 12 volts. The little Harbor Freight pumps are about a 6 volt motor or so, and WILL FRY when you hook them to 12 volts.
Buy your equipment first, then your solar system.
After you have everything hooked up and tested on a battery, get a cheap voltage tester that will test amps. (wally world, etc.) and hook it up in-line between your battery and the load. (your cooler AND whatever else you will be running) Turn everthing on, and see what the amp reading is, then buy a panel and regulator that puts out MORE than that. You can also estimate your needs by adding up all the rated amp draws of all the items, and get a system that puts out at least 2 amps more than that.
Alternatives:
Just buy a large capacity deep cycle battery and if it runs low, charge it from a running vehicle for a while with jumper cables. It would be cheaper if the system would only be used once a year.
A solar panel and small battery, being charged every day, (correctly) will probably perform just as well as a large battery with a big reserve, but for less time if the sun isn't out. (If you are shipping things, the weight is less.)
You can run two or more small batteries to give more reserve. But, try to match them. ( both new, rated close to the same, etc.) and hook positive to positive, negative to negative, and you have doubled your reserve capacity.
I know someone will get on here and say they have run this or that on just a 20 watt panel with no battery or charge controller, and they may have, but, they may have a pump that can take it, their fan might be rated up to 16 volts, they may be lying, you never know. I wouldn't trust a setup like that without testing it first and making sure it functioned.
HAVE FUN!
time to put in my order for duracool pads, think i'm gonna order a roll since we have a few to build
Maybe getting an extra HF pump would be a good idea 
I wonder if home depot changed their dimensions slightly *shrug* Did a trip check on measurements this morning 30 inches sadly does not cut it for my bucket.... BUT do not fear nothing that a minus 1/4-1/2 trim can't fix.... I hope!
