Instructables

Waterproof, Solar BOOMbox AKA: Post Apocalyptic Power Supply

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Picture of Waterproof, Solar BOOMbox AKA: Post Apocalyptic Power Supply
This project was inspired by a friend's build. It's made for extreme circumstances like Whitewater rafting, and after the meltdown of our electrical grid. I'm pretty sure you could throw this thing off of an extreme cliff and it would survive, more or less, intact and working. Also, it is extremely heavy. [OK maybe not Extremely, but pretty heavy] I entered this into two contests, so if you like the idea please vote for me. My friend's original build was very basic, and required a tape adapter to play from another device, like an iPod or such. I saw a couple of features that I wanted to add, for my own sense of functionality and simplicity, so I started collecting materials for my own. The project languished on my bench for at least a year before I heard that Joe was refurbishing his old box. This was the inspiration I needed for getting off my duff and finishing my own box. Now I'm ready for summer!

Here's what I wanted out of this project:
Reasonable battery capacity, ability to recharge itself, reasonable audio fidelity, rugged durability, ability to charge/ power other devices [music players, phones, raft inflaters].
As far as I know, so long as I don't let the battery go flat for too long this box should be able to provide electricity and music for years without ever plugging it into the grid.
 
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Step 1: The Box

Picture of The Box
I chose to use a 20mm ammo can. It's roughly 17"w x 7"d x 14"h. There's plenty of room for a faceplate including all the accessories and equipment, with enough left over for a music player. I like the ammo can for it's sturdy-ness. I feel like I could toss it off a cliff and it would be no worse for wear.
Other options I considered were Pelican cases, tool boxes, and suitcases.

a rigger (author) 2 years ago
If any of you want to see how this project is done by a real pro, check out Noahw's build. Nicer equipment in every way. [except for the sideways speakers :)]
http://www.instructables.com/id/Waterproof-Solar-Powered-Boom-Box/
a rigger (author)  Dr.Bill1 year ago
Thank you, Doctor.
rancidbry1 year ago
Amazing boom box! What was the total cost for this project?
a rigger (author)  rancidbry1 year ago
Well, to be honest, I didn't keep track. I had to purchase a couple of things twice because of failure to plan/ etc. Something like $45 for the box, $75-95 for the deck and speakers. $40 for the battery. The rest I had laying around. I think you can get that solar panel [which is undersized] for $15. And a jump kit with a fresh battery is pretty cheap too. If I knew what I spent on some of these projects I'd probably quit doing them. :)
pacornwell1 year ago
I am building this panel now and was wondering what the small LEDs are for? Did you use a regular 12V power supply and just wire it in to the panel.
a rigger (author)  pacornwell1 year ago
The 'jump kit' I used for some of the parts had a light switch which operated a poor excuse for an incandescent bulb. So I found some cheapo leds at the auto store. Useful at night, and gives off an dim/ eerie glow. At present I charge the battery via a really basic wall-wart type trickle charger with alligator clips on the external posts. No power supply but for the battery. Also a note: If you have a leak in your garage roof, avoid placing the open box directly under the drip... I haven't had the heart to fire it back up after discovering it half full of water the other day.
a rigger (author) 2 years ago
New update: Discovered, what I believe to be a critical flaw in my system.
The solar panel hasn't got enough juice to overcome the natural discharge rate of the battery. According to a friend of mine who sells batteries and solar chargers teh minimum output value [in amps] for the solar panel should be 1/10 of that of the battery's capacity [in amp/ hours] for it to effectively charge. The panel he showed me that would barely comply with that is about 4 times the size of the one I've got... So, next time I have the notion I'm going to try to find 3 more like it and stitch them together. Kinda like Noahw's charger but ... hackier... That said, with any luck that won't happen for a long time... I have stuff to do, so until then... Sayonara.
a rigger (author) 2 years ago
UPDATE:
The HF solar charger seems to be ineffective. I am replacing the tiny charge controller-in-a-car-plug with a more robust charge controller.
And the charging input plug from the jump kit is also a dud. [I'm thinking that's why the original battery went flat, and would no longer charge.] In the short term I've replaced that with an off the shelf battery charger. Hoping to find a suitable connector to get from there through the faceplate.
I was thinking of doing something similar with a 12v laptop power supply. would that work to charge the battery while the music played?
a rigger (author)  liquidflorian2 years ago
A power supply will charge the battery, but I don't think it has a means to stop itself before the battery explodes... Could be wrong. A simple wall charger works well and can be found pretty cheaply. That's what I've ended up with, and it seems to be working well.
noahw2 years ago
And, by the way, awesome project! I love things in 20mm boxes! I raft (a lot) and we store all kinds of goodies in ammo cans...even poop in the 25mm ones.
klincecum noahw2 years ago
Why wouldn't you just poop in the woods ?
a rigger (author)  klincecum2 years ago
Along popular riverways it's common for people to carry out their waste. Imagine a hundred people a day pooping along the riverbank... It's a good rule. Some rivers require you show your system before issuing a permit.
a rigger (author) 2 years ago
Finally got out on the river with this box! It played music all day, and still had enough juice to inflate my 16' raft at home afterward. I do need to go back in and sort out something with the charging systems...
MartijnD2 years ago
Advise: to prevent charger or solar panel conflicting it is good to add a big diode in the direction of the battery, this way there is also no leakage current back to the charger or solar panel: battery stays full when not charged. Keep in mind what the charging current and differential voltages are: diode must be able to handle the current and diodes have a small voltage drop as a result, if the battery is 13,8V and the diode needs 0,7V then the charger should be at least 14.5V. Check the actual values before ordering the diodes!

Bosch powerbox professional radio beats every radio normal persons can make: made to withstand a 9meter drop on concrete, rain proof, and a lot of sound, only setback is 250$, or 300 for the extra charger function, more sound and remote, but both are the best money can buy... You can use it at a party outside with 50 guests and it is still too loud!
a rigger (author) 2 years ago
Well, I used the electronics that came onboard with the solar panel and the jump kit.
The solar panel's circuitry was built into an automotive 12v cigarette lighter plug. I ripped the board out, replaced the built in fuse with an inline type from the auto parts store, and wired it directly from there to the battery.
Same goes for the wall charger. I ripped the circuit board out of the jump kit, and wired it just the same way it came.
I did no research on what those electronical elements actually do, I simply assumed that if I stuck to the same general configuration as the original, I'd be just as safe as the manufacturer intended.
In short, I shot from the hip.
I would guess that if you are including a charge controller you should run all of your charging sources through it.
noahw2 years ago
I'm curious on how you wired everything up. I just happen to building something extremely similar to this and wanted to know more about what you mention in step 3. I've got a 12V battery that I'd like charge from a solar panel, with a charge controller, and also by wall plug with 12V DC transformer. The battery powers a car stereo as well as some 5V USB accessories. How did you wire yours up so that the wall charger didn't dump power to your stereo, but did charge the battery at 14V. I'd love it if the solar panel and or wall plug could charge the battery while the stereo played. Thanks for any input you might have!