How to Solder With an AA Battery and a Car Battery





Introduction: How to Solder With an AA Battery and a Car Battery

You will need a car battery, AA battery, Jumper cables and solder. Touching the carbon rod from AA battery with the solder closes the circuit - this produces heat (& light!) that melts the solder.
What is interesting is that heat is localised and is present only for a very short time (sort of induction cooker).
Be very careful with the car battery and use a battery in perfect condition - I would suggest to use a battery charger (choose one which is fused) instead.
Do the experiment outside the house where air is circulating and wear arc welding goggles and filter mask.
A video of the results is here:

Step 1: Hack the AA Battery

This is a very messy step.
You will need pliers and a knife.
Be careful not to break the carbon rod.

Step 2: Carbon Rods

You will get bigger carbon rods if you use bigger batteries.
Here you can see one from an AAA battery.
The smaller ones are carbon (graphite) leads from pencils: here you have a 0.5mm and a 0.9mm leads.
Be careful with the smaller leads - they produce a very bright light and you will need arc welding goggles.

Step 3: Sharpen the Carbon Rod

For greater precision while soldering you will need to sharpen the carbon rod.
You don't need this step if you are using pencil leads.
Here I am using 2 dremels to do this nicely.
You can use a pencil sharpener although it is more difficult.

Step 4: Lead Solder

Cut a piece of lead solder with pliers.

Step 5: Jumper Cables

Get some jumper cables; Hold the piece of lead solder in one alligator and the carbon rod in the other alligator.

Step 6: If You Are Using Pencil Lead ...

... you will need 2 coins to hold the pencil lead, otherwise it will break in the alligator jaws!
(See picture)
You will need arc welding goggles because of the bright light.
Filter mask is also recommended because of solder fumes.

Step 7: Car Battery

Get a car battery and connect the alligators to the battery terminals.

Step 8: You Can Now Solder

A video is available below.
I am using pencil rod in this video.



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    62 Discussions

    Don't you think messing with a battery is very dangerous! It can kill you!

    2 replies

    pretty sure the battery by itself can't kill you. the amount of ristance from you skin, would prevent almost any amps from going threw you at 12v

    It's fine as long as it isn't short-circuited for very long. It would be fairly safe to solder with because the battery's 200 amp potential can't go through such a small diameter conductor as the solder. The only way it would kill you is by exploding from (extremely) careless use and/or starting a fire.

    I actually saw MacGuyver do this with a nail to add the tip bit to the end of a spark plug. Pretty freaking sweet.

    3 replies

    Actually, MacGyver coded Instructables on some scrap paper. He then proceed in using Duct tape to bring it to life.

    i heard that he used 500 million transistors from radio shack to make the server for instructables. Hes like the Chuck Norris of instructables.

    There's an easier way to use a car battery to solder:  Attach wires to the battery terminals and touch them to what you are soldering.  There will be a big spark and the solder will be melted (It might not be all the way soldered but hey in an emergency..)

    (+)  ----------  (solder) ------------  (-)

                         < Spark ! >

    I don't think you would need welding goggles, it is virtually like staring at a light bulb, the first light bulbs used carbon filaments, so is it a legality thing or something?

    1 reply

    There is essentially no filament here, this is an "arc lamp."

    Regardless of the intensity, arc lamps have very high UV emissions. Some sort of protection should be used--if you value your eyesight.

    There is only a certain type of Battery you can get Graphite from, Ive found em at the dollar store. The type is Zinc Chloride (These are usually marketed as Super Heavy Duty Batteries) and they will NOT say that they are alkaline types, as those are useless to get graphite from.

    D and C cell type batteries have larger electrodes inside of them, so they are probably easier to handle.

    1 reply

     I was just about to comment my very same discovery about this.

    My conclusions?
    -Only the ones marked "Heavy Duty" as you said (however it wasn't mentioned what exactly it was) have the graphite. The others all have some gooey stuff in the middle.
    -My family likes to buy a lot of Duracell. (NOT with graphite).

    So yeah, out of a nice mess I only extracted 1 rod. All the others were alkaline (Duracell).

    I think every person I know either currently has or has had a Linksys Router. I mention that because the Linksys Router wallwarts are 12 volt, at 2 amp. stone3408 mentions a one amp 15v wart, so I figure the Linksys wart would work well. I probably wont try this because I can easily see how it would work, but will CERTAINLY keep it in mind in for roadside repairs like bleachworthy mentioned. My question is, would someone rate the following batteries from most dangerous to safest for this particular project? I have a VERY VERY large flashlight, 15,000,000 candlepower. It uses a sealed rechargeable 12v 7a/20Ah battery. How about the similar sealed 12v rechargeable starter battery in a Pocket Bike? (I do not know the amperage of this battery.) The battery in a "Jumper Pack" or "Self Contained Jumper Cables" with a supposed rating of 300 cold cranking amps?

    1 reply

    This is actually quite dangerous because of two reasons really: 1) You have a good chance of getting shocked with a high amperage-enough to knock you down or seriously injure someone with a pacemaker if it goes across your heart. 2) You are shorting some pretty big car batteries there which can cause them to explode, or leak which is definitely something you don't want happening. Read the small print on the battery to find out.

    5 replies

    Absolute nonsense on #1. 12 V is not able to drive a high current through your body (which is the only one that matters). #2 is correct, though. You definitely do not want to short circuit a car battery (I speak from experience, unfortunately)

    hmmmmmm consider the Ampers and not only the Voltage...10-12 A are enough to sock and harm you seriously. Think that 12V/10A gives enough power to start an engine. In addition all the materials you use are high risk under the electricity. On the other hand if you don't even have an solder gun then you will carry a dremel? and of course as Cpotoso already said maybe after that your car need other battery so consider also the cost!!! Sorry man, nice as idea but for Breaniak so NOT DO THAT AT HOME!!!

    Again: 12 V is NOT (NOT NOT NOT) able to drive a significant current through your body. The electrical resistance of your body+skin is in the tens to hundreds of kilo ohms. With only 12V of voltage, a simple application of Ohm's law gives a current of less than 1 mA. Not dangerous at all, save some very few very convoluted cases (e.g. if you put electrodes inside your body, not a good idea if you do not know what you are doing!).

    dear Cpotoso. some years I had an accident. I touch the battery poles at the exact moment when the engine started. After 12 years even now i have from times to times some pathetic moves of self stimulated muscles. The power was 12 V but the amps were around 45!!!

    well the graphite lead has an extremely high resistance, and will most likley keep the battery in check