Introduction: How to Make AC Powered "Batteries" for Your DC Powered Devices
I made this copier recently, based on a digital camera and a stand. I dig it. I also made a few modifications, one of which I show in this instructable.
The digital camera I use runs on 2,000 AA batteries, though it uses only 2 at the time. But it eats through these things. It laughed at rechargeables. It cleared 8 batteries in its first day of service. I’ve read that sadly, that’s not abnormal. It’s a good camera, but the cost of batteries was going to render this project prohibitively expensive to operate.
There is no DC input adapter to use an AC power source with it, and my search for how to add one left me frustrated — the few walkthroughs I could find were good, but would require MASSIVE modification to the camera given its size.
So, I had this idea, put it together quickly, and it worked. The goal is simply to run the wire ends from an AC adapter to the contact points in the camera. Almost no modification to the camera [just enough to let the wires through], very inexpensive, and quick to make, simple, and effective.
I didn’t find any instructable or even blog written about this concept. I independently discovered and engineered the solution I will show you. There are likely better ways. Please tell me of your improvements in the comments. If this is your idea, let me know so I can credit you.
*** Obviously this will likely void your warranty. It is intended for devices WITHOUT an AC adapter socket. If your device has one, by all means use that.
Step 1: Tools Needed
What you’ll need:
AC Adapter (I used the universal kind. This turned out to be REALLY useful for me as I’ll explain later). An old one lying around that’s of the right voltage and amperage would be fine.
Batteries for the device you’re wanting to power. In my case, that’s 2 x AA batteries.
The device you’re wanting to power. In my case, a little digital camera.
A pair of small, short screws. Just about anything you have in your tool box will work.
A saw (apartment = handsaw, even though I want my circular saw).
Wire cutters / strippers
Dowel of proper diameter (this is on you. Also, it’s ok if it’s a little too small. It’ll work. Too big and you have to shave it or it won’t work).
Vice (or drill/drill press)
***** CAUTION ***** You’re not an idiot. You are dealing with electricity, sharp things, heavy things, and heavy sharp things that use electricity. Be careful. I didn’t hurt myself, and that’s saying something.
Step 2: Cut and Strip the Wires
My first step, whether it made the most sense or not, was to cut the end off the AC adapter. Then I separated the wires down a few inches, enough to feed each wire through a dowel piece, and stripped the sheathing a little.
Why did I cut the power cord first? Because once I did, I knew I couldn’t return it. Once I did, I’m in until I’m done.
Step 3: Measure & Cut the Dowel
Now measure the dowel and mark two lengths, each the same as a AA battery. I just put the AA battery up to the dowel and marked a hair less than that (the screw we’re putting in later will let us adjust the length a little, so better to be a little short than a little long). Go ahead and sand them while you’re at it.
To find the dowel size, I actually googled up an image of a battery showing all its dimensions. I took it to Home Depot, but also took a battery with me. I found a dowel the size of my battery. As I said, I used the battery to measure the dowel lengths. Moral? Don’t make things more complicated than necessary.
Step 4: Test Fit the Dowels
I dropped the batteries into the camera, then the dowels, to see that they behaved like the batteries. That is, did the door close, but I feel a little resistance from the spring? Do they rattle around against each other too much? This is the time to sand them, cut them shorter, or cut new ones altogether.
Step 5: Drill the Screw Holes & Thread the Wires
We’re going to use one screw for each battery to act as the contacts. Place one of the short dowels into the vice and drill a hole all the way through, vertically (see picture). 5/8 in. should be plenty, but you have some wiggle room. The holes need to be big enough to feed your wire through, but not much bigger. You want this to act as a pilot hole for your screw, which you need to lock into the wood tightly later. When you’re done, go ahead and feed one of the wires through one of the dowels, then do the same with the remaining dowel and wire.
Step 6: Mark the Ends
This is important. It can save you a lot of frustration later. Mark the ends of the batteries. Remember, only one end of each will have a contact, so you need mark only one end. But mark them. I did this by using a kitchen timer that takes 1 AA battery. I touched my wires to the leads in the battery compartment. Nothing. I switched them and I got a beep and a working timer. Looking into the compartment for the + and - signs, I now knew which wire was which. For me, the wire with writing on it was the negative. Yours may be different, so test first. You could also use a meter. Feed them through the dowels and mark the dowels.
Step 7: Wire the Screw and Drive It
With the wire pushed through the dowel and stripped at the end, you can wrap the wire around the screw body. It is important that you wrap clockwise as viewed from above (or counter clockwise if you have a weird reverse thread). This will make it such that when you drive the screw in, it will actually bring the wire with it, wrapping tighter. If you wrap the other way, the screw will actually unwind the wire as you drive it.
Go ahead and drive the screw into the dowel. I used a manual screw driver for this and recommend the same for you. It doesn’t take long, you have a pilot hole, and you want fine control over how deep the screw sinks.
You’re basically done. Drop you’re new batteries into your device, make sure the batteries are plugged in, and power up. It should work. If not, check that you have the proper voltage and current going to the batteries for your device. In fact, check that first. It’ll save you from burning a $50 digital camera by feeding 9 volts to it instead of 3 (accident).
You’ll likely have to hold the batteries in place b/c the door will likely not close b/c of the wires. To solve this, I dremeled a small notch in the battery door to accommodate the wires without rendering the door useless. After all, I don’t want to hold these batteries in the whole time I’m scanning documents. Also, my modification was so slight that it’s barely noticeable and still allows the camera to take batteries. I expanded the camera’s function rather than change it.
Step 9: Final Thoughts
I burned a camera. Check voltage and amps BEFORE turning devices on.
You shouldn’t get shocked, but you could. BE CAREFUL. Also, you shouldn’t get bitten by a snake in your car, but stranger things have happened. BE CAREFUL.
You can make C and D batteries and even AAA too. 9V make take a block of wood given the shape. If you’re making a device specific battery, engineer the most efficient way to get power to both the positive and negative terminals of the device so that the wires and contacts hold themselves while still allowing for the use of DC batteries later.
A table vice clamped to the kitchen counter works wonders. That’s how I did this project. Just be careful not to damage your counters.
Good Luck. Have fun. This project shouldn’t take long once you have all the parts. I expect to make some more of these soon, once I find something else that I need to be AC powered.