How to Make AC Powered "Batteries" for Your DC Powered Devices





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 screwdriver

A saw (apartment = handsaw, even though I want my circular saw).
Sandpaper/sanding block

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.

Step 8:

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.



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93 Discussions


2 years ago

I like your idea about using dowels to make the battery connectors. I am making a Raspberry PI 2 laptop and I am using a wireless touchpad that requires 2 AA batteries. Since the batteries only last two weeks at a time I need to get a better power source. I ordered an XT Power 10,000mAh battery pack that puts out 12 volts (for the monitor) and 5 volts (USB Connector for the Raspberry PI) I am going to add an L4931, 3.3 volt Linear Voltage Regulator to bring the voltage from 5 volts to 3.3 volts. Thank you for the idea!

Thanks for sharing your idea and your humble teachable spirit. If there are better ways, this will spark creative discussion.

Or you can just UNSCREW the camera, open it up, find the contacts inside the camera, where it would recive power from battery and solder male and female headers to make your own DC power jack for the camera

You can assemble the ciruit on a general purpose board and use and ac adaptor. Circuit is polarity free at the input. use any AC adaptor without worrying abt the polarity at the pin and voltage rating. The output will be 3V always. You may always want the regulator IC LM317T mounted to a small heatsink for protection. Just be sure to insert the batteries correctly. Hope this makes things safer..

2 replies

great idea, always be safe and use a multimeter to make sure you have the proper voltage (ac/dc)

Hi Ispcrash,
I have a variation of the AC powered "battery." One piece supplies power and the other pieces are conductors. Even though the voltage is underestimated, it's not an issue when my LED lamp is current regulated but the regulator does get very hot dropping 3 or 4 volts at 0.7 A.

Good project, but I should probably point out that you are using a DC adapter, not an AC adapter. If it was AC, you would easily get shocked, and you would blow up the camera. And yes, ALWAYS check the voltage of the DC adapter to make sure it closely matches the batteries you are replacing. (1x AA = 1.5 V).

5 replies

Excuse me , you said that he is using a DC adapter, but the power comes from an AC outlet, so they are AC powered "Batteries", right ?

The power comes from AC, but the adapter is a DC adapter, as it converts the AC from the wall into a DC signal. Technically it is an AC/DC adapter, most commonly shortened to DC adapter, to clarify which type of power is coming out.

I never suggested the title was wrong, I was merely pointing out that anyone doing the project should ensure they are using an adapter that outputs DC voltage.

Step 5 concerns drilling holes through the ends of the wooden dowels, and specifies 5/8" diameter, which must be a typo. 5/8" would be close to the diameter of a AA battery. The diameter of the holes need only be slightly more than the width of the wires.

1 reply

Yeah that was a typo. I don't remember now what size drill bit I used (5/16" maybe?) But you're right. All you need is a hole slightly wider in diameter than the wires themselves. Good catch.

I done this for my wireless phone last year. my phone burnt out after 1 month, caused by unstable power source. So, I think is it posible to use rechargable battery inside gadget and connected to direct charger, the gadget will receive more stable power (voltage).

1 reply

A capacitor would do the job well. I suggest testing with an oscilloscope to find the necessary amount of capacitance.

My brother did more or less this years ago with an old caller ID box. The connector broke so that the 9-volt battery had no place to attach anymore. He cut the end off of an adjustable AC adapter, set it to 9V, and attached the ends of the wires to the leads in the battery housing. Worked perfectly.

i had thought of this type of idea but never got round to doing it, glad to see it in operation and it does look a good result with minimal disruption to the unit, i have a power monkey which is a long lasting portable battery power source, it comes with many adopters for many different devices but i wanted to see if it would run my camera as it eats batteries so now im inspired to do the project with this as a part of it as it has no external power socket.. thanks btw just heard of a new high powered rechargable battery called "eneloop" ,reports are that they are great, google them.