Make a solar charger and stereo from an old cooler

Materials Part 1

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solar cooler stereo parts

credit: jtjaeger

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Cooler:

I chose the 16 Quart Igloo Playmate cooler for this build, since it's big enough to hold everything, but still small enough to carry with one hand. The roll top is also quite useful, and makes access to everything very easy. (~$20, Target/elsewhere)

Faceplate:

I used an scrap laminated bookshelf to mount everything on. I've used thin plywood for this before, but a thicker piece of wood makes the acoustics much better. (free/scrap)

Stereo:

Any standard 12V auto/marine stereo deck will work. I used a basic marine unit, since it somewhat more water resistant than a standard car deck. The cheaper units are "Mech-less" and have no cd-player. You could reuse an old unit, and go pick up a used deck from a junk yard / scrap exchange. ($30+ depending on features, Amazon/elsewhere)

Speakers:

I used a pair of 5.25", 150 Watt, 2-way marine speakers, which fit quite nicely given the playmate dimensions. While you could use regular car speakers, marine speakers are waterproof (in theory) and are usually built to take more impact and abuse. Again, this is a spot where you could pick these up on the cheap as used car parts. (~$20, Amazon/elsewhere)

Battery:

Small 12V AGM lead-acid batteries are very easy to find, as they are used in computer UPS units and fire-alarm systems. Like all batteries, their capacity is rated in Amp-Hours (Ah). Choosing the battery size is a trade-off between Ah capacity and weight, as this is by far the heaviest part. I chose to use two 12V, 8Ah batteries (wired in parallel for a total of 16Ah). At moderate volume, my stereo draws approximately 1 Amp, so in theory I could play music for 16 hours if I drained the battery from 100% to empty. Admittedly, this is overkill, you could get by with 5 - 10 Ah. (~$20 for a 8 Ah battery)

Solar Panel:

Solar panels are getting cheaper by the day, and you can find a small one on eBay or elsewhere fairly easily. Since the battery is 12V, you want a solar panel that is rated for 12V. The "open-circuit voltage" of a 12V solar panel will be around 18V, but the charge controller will prevent overcharging. The size of the panel should depend on the battery size. As a starting point, I would suggest matching the wattage of the panel to the amp hour rating of the battery (10 Ah battery, 10 W panel), but also considering what loads you will have (a stereo will draw 5 - 20+ W). A 10 W panel will have an effective charging current of approximately 0.6 amps (10W / 18V), which will charge your battery from half to full in about 8 hours of full sun light. I used a 10W solar panel, but this will depend on your needs. (~$35 for 10W panel, ebay)