This is one of those things that's so practical and so obvious you wonder why you don't see more of these things.
This instructable will teach you how you can bring 120V of power with you anywhere you go, using a deep-cycle battery and an inverter.
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Step 1: What You'll Need
Deep-Cycle Battery (for marine or RV use): This kind of battery is meant to provide moderate amounts of electricity over long periods of time.
Battery Charger: This lets you charge up the unit by plugging it into the wall.
Inverter: To change the current from 12V DC to 120V AC. The more watts, the more power you can draw at a time. We used an old 100W inverter, but in future builds, I think I'm going to kick it up to 400W
The Shell: Luckily, I had an old Fender bass amp box lying around. Good luck finding your own.
Switch: So you can turn it off when you're not using it.
Some scrap wood: I used this to make a shelf for the inverter and charger, as well as the front panel.
Multi-plug adapter: Notice how the inverter only has one plug? Well, I wanted to split it so I'd have three.
Zip ties: To secure everything down.
Nails, wood screws and/or bolts: I used nails to secure the inner shelf and bolts to secure the handle, which is clearly broken.
Step 2: Connect and Test the Electronics
Connect all the parts of the electronics to see how it works. Red to red, black to black on the charger and the inverter.
If everything works right, you should be able to draw power from the inverter.
You can start using this thing immediately. But if you care about building a housing for it, keep reading.
Step 3: Secure Handle and Inner Shelf
These batteries are REALLY heavy, so I secured the handle with bolts to make sure it wouldn't go anywhere.
Then I did the shelf.
Find a good height for it where you have enough room for all of the electronics and the battery, then draw a line to mark it inside the box.
Drill two small pilot holes in each side (see second picture), so you can make sure that you line up the slats with the nails. Then carefully line up the holes with the nails and slowly pound them in. I put an extra nail in the middle, with the pilot hold, so there's three nails in each side.
Step 4: Fasten Charger to Shelf
I did this using a technique I like to call "Zip Tie Lashing."
Basically, you can string zip ties together, end to end, to create a longer zip tie. Close it into a loop, then come from under the shelf with it and slip one end up over each side of the charger. Tighten this the best you can, but don't worry too much about making it snug.
Then, use another zip tie (as pictured in the second picture), to to squeeze your first zip tie band into snugness. You can use pliers to pull back on it until it's super tight.
Step 5: Making the Front Panel
Wait until your neighbors are doing construction, so that you can have their carpenter come cut out holes for your outlet face. (At least that's what I did).
It's much better to cut the face too small than too large. I had to tap mine in with a hammer, and that seemed to wok very will at keeping it in.
Then, I covered the holes with tape and used liquid nail to seal in the cracks. Once it dries, I'll sand it down, and maybe paint it black like the box.
Step 6: Installing the Switch
So, I'll admit, the switch was an afterthought. After I got everything in place and was about to seal 'er up, I remembered that I needed to be able to turn the thing off.
Luckily, I was able to find a push-button switch in my box of random parts, and installed it in the line going to the positive battery terminal. See the pictures for more detailed instructions.
Then, I had to mount it in the front panel. I drilled a small hold, just big enough to be able to slip the button through without its cap. Because the cap was bigger, I had to drill in with a bigger bit from the other side in order to be able to depress the button.
Then, I covered the back terminals of the switch with electrical tape to insulate them from each other.
Step 7: Put It All Together
The front panel and the battery aren't actually connect or secured.
The front panel is just a hair too big for the space, so I really just tapped it in with a hammer. I would have secured it, but I'm planning on getting a better inverter soon, so I didn't want to make it to permanent.
As picture No. 2 shows, I got really lucky with the size of this amplifier box. The spacers let the battery sit securely, and it's shear weight keeps it in place.
The last step was to secure the back, drilling a small hole for the cable to exit.
Step 8: Plug in to Charge
Your unit should be ready for power anywhere. Just plug the tail into the wall to charge it, and when it's done, you're ready to go.
One shortcoming is that you have to peak up inside to see the charging status. Red means charging, green means full, and they flash to indicate other things.
Step 9: Suggestions for Future Improvements
I'm pretty proud of this afternoon project, but with some more thought it has potential to get a lot slicker:
*The status lights on the inverter and charger could be re-routed to the front panel.
*A cover could be placed on the front, just making it a black box of power.
*Wheels. If you picked it up, you'd understand...
*Adding more power options, such as a DC socket or USB ports to the front panel.