Power Devices With Old Batteries


Introduction: Power Devices With Old Batteries

About: Andrew built a power supply after shocking himself when he was four. He's been taking apart and building things ever since.

Power smaller devices with your batteries from cameras, remotes, GPS that won't turn on because they are too weak. This clock/calendar/thermometer uses a 3V watch type battery. It lasted 4 years until the battery drained to 2.44 volts. New batteries come with even more voltage, for example the new AA 1.5 batteries measures 1.59 volts. So the clock will run well within 2.5-3.1 volts.

Cost: Free

Savings: $6.27 (source: newark.com)

I measured the soldering iron usage with my Kill-A-Watt. My 30 watt iron used 28 watts for 8 minutes and didn't even register 0.01 kwh so it cost less than 1 cent.

Step 1: Find a Low Power Device

1. Find a device that takes less power than your camera. The clock only needs to run the lcd and simple electronics. The lcd is very low power because it does not have a backlight, lots of segments, or color. Find something that takes 2 AA batteries or less or even smaller batteries.

Step 2: Check Your Old Batteries

Check your old batteries for ones that have a good voltage with a volt meter. I ended up using two AA batteries at 1.44 volts and 1.39 volts. They won't run a bigger device but in series they have 2.82 measured volts. The clock will run down to 2.5 volts.

Step 3: Solder Batteries

1. Strip wires for attaching to batteries and device. I used extra cat-5 Ethernet cable cut to 6" and stripped at both ends.

2. Tin the wire and battery separately then quickly solder together. Do Not solder watch sized batteries, another website says they explode, you also do not want to heat up the batteries long so make connections quickly.

Step 4: Connect the Wires

1. Twist the battery wires together in parallel and connect to a lead that connects to the device. The clock had tabs for the battery so it was easy to crimp them on with needle-nose pliers. If you solder them, do not overheat the circuit board of the device.

2. Close it up or tape it so the wires don't touch. The clock has a slot for a screwdriver to pry open the door so I just ran the wires through the space.

Step 5: Secure Connections

I just twisted and taped the leads so they don't touch and I can easily replace single batteries later on. You could secure the connections better by soldering and containing them. There is enough room in the clock body pencil holder to hold the batteries but I like the mad scientist look of the wires.



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    I don't think you can power cell phones any more with anything other then a battery supplied by the company who makes the cell phone. All new phones have a smart chip in them to prevent the phone from working on any battery other then that programed by them. It came about because of all the defective li-ion battery explosions & just plain greed but mostly the company's took steps to prevent this from occur in any of there products & being sued ,plus they can sell you a new battery for a over inflated price ! I tried to power a LG cell phone with a wall wart of proper voltage and amp & it would not power up only with the battery which was being sucked dry by a defective power monitor chip. Now who did not see the cells phones use the li-ion explosion scare as an excuse to push there batteries at inflated prices in hopes you will buy a new phone ?

    Ya, watch batteries explode and when they do, it feels like a shotgun filled with flour is fired at your face...

    Yes it will work. I would not do it with my cell phone because if anything shorts out or you don't get something right you could fry your cell phone. If its an old phone and you don't care if it dies then you could try it. My phone is 3.7v and also says 1100mAh which is milli amp hours. That is how many amps the battery should produce for an hour. A regular AA battery new has at least 1100mAh. So as long as you string (series) to get the right voltage as close to you 3.6 volts it should turn on. If you want it to last longer, you can put together another set of batteries at 3.6 volts, and add them in parallel. The voltage will stay the same 3.6 but your milliamps will go up. Any small battery should be ok, but dont try to hook it up to any bigger batteries like lantern, laptop or car, they will probably have too much current (amps) and blow out your phone.

    would this work 4 another cellphone batt (same voltage) that just doesn't fit? and also would only 3v do thx

    I'm not sure what you mean. If you mean can you put a cell phone battery that doesn't fit into a cell phone by soldering then yes you could. If your phone normally is 3.7v and the battery you want to use is 3v then I would not do it. The charging mechanism designed for the 3.7v might be too much power for the battery (explosion risk?) If the battery is just low on power and only produces 3v and you need 3.7, it wont hurt to try it by just wiring it up and see if the phone turns on. Almost all devices have a threshold where they will not work below a certain voltage. 3volts instead of 3.7volts is probably too much but worth a try. Like my clock, it is rated for 3 volts and will run down to 2.5 volts. Make sure that you don't care if your phone dies!!!

    i mean can i put wires on a charged cellphone battery and touch the wires to the terminals (hook up a 3.6 volt battery to a cellphone wich uses a 3.6volt battery by wires touching the contacts.

    Yeah that should work fine, just make connection and get the polarity (+ and - correct.

    like i found this dead cell without a charger could i hook up a batt from another cell with the same voltage (wires)

    Nice job. Good idea, and it looks easy to do. Looks a little weird having it stick out, you should put the batteries in the back of it or something. Awesome Instructable still.

    3 replies

    you could always just buy a battery clip... and solder the wires onto that. thatway its easy to replace the batteries when the finally drain completely.. and easy to switch it to some other electronic device.

    You could use a battery clip. I would recommend it if you want it to be durable. They are as cheap at $0.30 online but shipping costs as much as just replacing the original battery ($6.27). If you go to radio shack they have one for $1.69 + cost of trip (if you are only getting a battery clip for this project). So if you have the soldering supplies, you can save the full $6.27.

    Thanks, I'm keeping the batteries out next to the inside of a vacuum motor I have decorating my shelf. My goal is to have at least one room, basement, or garage resemble Doc's lab from BTTF. If I want to make them invisible I'll just tape them up and put them in the bottom of the pencil holder section behind the clock.

    Nice job, if only people would start to recycle it's own batteries... Btw, it's in series that voltage adds up, not in parallel as you wrote on the 2nd step! :)

    It's usually not a great idea to solder directly to batteries, but I can't say I haven't done it in the past! It's a pretty good idea, but it's too bad I don't keep any of my bad batteries...