DIY Battery Powered Soldering Iron

When it’s time to get started on a project and put our irons in the fire, we usually reach for a nice Weller or Hakko soldering iron. Unfortunately, that isn’t possible when we’re soldering something away from a wall outlet. Portable soldering irons usually range from slightly to completely terrible, and [Adam] thought he could do better. He put together an Instructable for a portable battery-powered soldering iron that’s extremely easy to build.

[Adam]’s project mounts a standard Radio Shack soldering iron tip in an E-10 flashlight bulb socket. Power is provided by 6 Volts of AA batteries, with a small switch added for the obvious safety concerns. Although [Adam] could have added a small project box, he chose to build his entire project around a piece of wood. This is an excellent choice in our humble opinion; wood doesn’t melt, has very low thermal conductivity, and anyone using this iron should be smart enough to turn it off if the handle starts smoking.

While this isn’t the best possible portable soldering iron (we’re partial to the disposable-lighter-fueled torches with a soldering iron attachment), it’s much better than the ColdHeat soldering iron that received consistently bad reviews.

Edit: [Adam] updated his build to be a little safer after this story was posted. We changed the original title pic to reflect this; here’s the old one.

46 thoughts on “DIY Battery Powered Soldering Iron

  1. Cool, but I can’t imagine a useful battery life. Weller P2C runs over an hour on butane, refills in seconds and is genuinely good enough for nearly anything, save for small SMD work. Can be had for under $30…

    1. I got one at Radio Shack, but the tip was completely ruined before I even finished soldering the 2×1″ board I was working on, despite proper tinning and reasonable temp control. I got another tip and it went just as quickly.

      I wonder if they’re plated with something that dissolves in tin?

  2. Cold heat is crap because of how it “works”. This build seems to be lacking in total power. Most soldering irons are 20 – 60 watts. 4 AA batteries is 6 volts and about 2700 mAh each so 16200 mAh or 16.2 amps at 6 volts for one hour (theoretical).

    So in theory, 97.2 watts for one hour out of 4 AA batteries. In practice, mAh capacity isn’t for quick discharge, it is generally 20 hours or more. Heat build up is neglected, etc. But I could see this working, at least in a pinch.

    1. Wrong. In series, the capacity does not add up, the voltage does. If they are in parallel, then the total capacity increases. So we’re looking at 2.7ah for this application, not 16.2.

      1. Bah. Correct. Can’t have both voltage AND current add. Gotta pick one. So 2700 mAh total @ 6 volts so… about 16.2 watts (in theory) or probably closer to 12 – 14ish due to internal resistance, real world, etc.

    2. You can’t measure the ColdHeat’s power in watts relative to a normal soldering iron. ColdHead is more akin to an arc welder than a soldering iron. The one I tested did OK, but the tip was pretty fragile. The battery life wasn’t really an issue since it was designed for small jobs and it had an instant on/instant off switch.

      It would be pretty miserable as your only iron, but for quick fixes, it did a decent job, IMO. I’d own one if they made the tips stronger.

    3. I loved my ColdHeat iron. It was fast, effective, and ran all day.

      The difference? My iron ate Sanyo Eneloops. Any other kind of high-current NiMH or Energizer L91 cells would have worked fine as well, but I prefer Eneloops because of their good behavior compared to most high-current NiMH; they usually end up flat dead a week after being charged.

      I burned mine out trying to solder a PhlatLight SST-90 LED that was attached to its heat sink, and was horrified to discover that they were discontinued. If any of you want to unload that iron you hate, drop me a line already!

      (PS: I have the oooold Radio Shack butane iron, and the current Radio Shack battery iron that the article’s iron tip came from. It’s all right, but I prefer the ColdHeat iron for being faster; the butane iron is great for big jobs, but is slow to heat up compared to the battery irons. I also need a new tip for it after I damaged the catalysts.)

    1. Respectfully; logically the wood used here isn’t a problem. Most likely will never see enough use to see the first hint of charring, much less raising the flash point to where it would spontaneously combust.

    2. I can see where you’re coming from, but actually only the very top part of the tip gets hot. The rest is insulated from the heat. This is why I mounted it on wood. It was a cheep prototype for me and others could build it cheap and easy. I actually updated my Instructable to show my most recent iron inside of an Altoids tin.

      1. I think I might prefer the wooden one myself. It looks more ergonomic. Plus, if it did get hot well.. wood doesn’t conduct heat very well. I could put it down and deal with the flame before the flame burns my hand. Plus, Altoids tins are kind fo thin. I wonder how much heat it can take.

        But.. I’m just a guy looking at pictures. Which one does the author who has actually used the things prefer?

  3. Had a cold heat, did ok on through-hole non-semiconductor components, but anything too large is no go, along with tool small. In addition, tip was super fragile, and it scarfed batteries.

    As for the actual post, useful life is probably less than 10 minutes. Should be careful that you only use alkaline batteries if you rig up something similar; rechargables or lithium batteries would at least be ruined if not causing a fire.

    No doubt you’d be better off using a butane torch both for ease of use and price per minute.

  4. This is probably one of the best hacks I’ve seen in a long time..maybe because I’m in Europe where you can’t walk down the street and buy one. or even order one(without ~$70 in s&h).

    1. Haha! Thanks! The reason that I made the iron not very elegant is because this is supposed to be an easy and cheep project. Actually, if you check back, I changed the design to fit in an Altoids tin!

  5. What you want is the Weller Portasol Kit. best butane soldering iron ever, runs about $60. I use it for soldering LMR-400 (giant-ass center conductor needs a lot of heat). Super-simple to start, don’t bother with the ratshack butane soldering iron.

  6. This is the Weller (branded) #P2KC portable/butane unit that *I* recommend:

    More info:

    Gives you adjustable 25-75Watt (equiv) heating power, heats up VERY fast, comes in a nice little carry case. Excellent for Arduino hackers, in the field soldering (I use it with my high power rocket work), etc. Really nice.. and worth the extra $$ ($60-80 delivered). Just be sure not to get the cheaper units that can’t deliver a full 75Watts (equiv). These things are ALSO compatible with the other whole world of weller tips! (P2KC tips)


  7. The only advantage I can think of of the hack over just buying the soldering iron from Radio Shack for $19.99 is that the batteries probably last longer than the NiCds in the RS iron. Cordless irons aren’t generally left on, but turned on via a momentary switch for each joint and battery life rated by the number of connections you can make that way.

  8. Not purty, but s nice build non the less. Some refinement would make it more ergonomic and compact. I’d add a LED for an on indicator. This not being a bench tool, I don’t think battery life a big issue. Perhaps a butane iron looks better on paper. I have heard and read smokers complain they can’t readily buy butane. However places that don’t carry butane generally carry batteries.

  9. Hmm nice, certainly a DIY job. Kind of thing I’d expect to see out in Africa and the like.

    I would as a first step to refining it, mount the battery pack in line with the tip, probably by scalloping a big ol chunk of wood out for it.

  10. I got a Weller P2C for Christmas (along with a pound of kester “44”) and the Weller has been seeing more use than my Hakko 936 since it is a lot easier to deal with when I just need to do one or two connections (or install a car head unit).

  11. and the tip is WHAT voltage? wow cool, i want to buy a tip of that voltage and make one myself!

    PS: i will be on the lookout, those low voltage tips look VERY appealing, 6v? use 5v smps (mod for 6v) and a 8AA/12v pack… hours and hours XD

  12. Weller has a small battery powered iron for quick smaller jobs. Heat up time is around 10-20 seconds and it’s great. It’s underpowered though for some of the larger jobs, but for spot checks, works great.
    Don’t mind the bad reviews because most of these people are expecting it to solder 12AWG wire or something. Expectations not meeting product specs.

  13. I still can’t find any experience of original author of iron featured in this post. For how long he can run this iron with 4 AAs?

    1 minute? 10 minutes? 1 hour? more?
    Is it different with NiMHs and Alkalines?

    All i can see here are just more or less educated guesses, but i don’t know if it’s worth building…

    I saw product based on similar principles called “Magic Flight Launch Box Vaporizer” being used to evaporate herbs. It lasts only few seconds of operation until battery is completely depleted. However it’s using only one AA, so voltage is lower but capacity remains same.

  14. One big issue with a soldering iron is the ability for it to damage or destroy components on any board. That Wahl or now Iso-Tip portable rechargeable Iron has an isolated tip design…thus the name iso-tip. It is designed to reduce or eliminate the issue of toasting parts. The small tip they make has more than 7 parts to it. The iso-tip 7700 does roughly 125 solder joints per charge depending on how good you are at soldering of course. The butane irons work well too as long as you do not have a confined space because they generate a lot of heat. The butane models also come in different sizes. The other nice thing with the Iso-Tip rechargeable soldering iron is that they make 20 different tip styles for it. They reach roughly 900°F in around 10 seconds.

  15. I thinkk its a brilliant diy project loaded with just made a launch pad for a 50 watt e cig.look at it again with difrant eyes and see what i mean.e cigs are basicly a heating element in contact with e juice. And i bet a soldering iron tip would more than out last a coil.not to mention the vape from hell.I’m working one one now but would love feed back. Feel free to email me at i love to talk vape period so any feedback is welcome.

  16. I used to have access to a pair of battery powered soldering irons. They were identical and both had docking stations to charge in but one had it’s heating element removed. In place an accessory was attached that turned it into a drill. It had a pretty small bit but it was a pretty good size for making holes in PCBs for leads or signal wires. I actually preferred my own butane powered iron for soldering. It was hotter and it got there much faster. That drill was very handy though! It ‘lived’ in it’s docking station so it was always charged, just waiting to be grabbed and used.

    Every now and then I search FleaBay but don’t find much. Does this sound familiar? Anyone out there know the brand/models I am looking for?

  17. Well this is an old post :P

    Anyways i got myself a USB soldering iron… lol and well it worked really great actually, but only for 5 minuts. Sooo i was looking around for someone who had figured out how to make one yourself and found all those with pencils, and old transformer from a sound amp.

    Anyways this usb soldering thing that i got has a detachable tip so you can change it. and it’s 2 parts well 3 i think, the tip, the outer “barrel” and inner “barrel”. The “barrels” are separated by some white hard stuff i guess it’s some sort of porcelain.

    So my question is, is that just the same as this tip that he uses, well this one has a e10 screw fitting but mine doesn’t but as long as i connect + to the center “barrel” and – to outer “barrel” since the bulb is + in the middle and – on the outside i guess the e10 soldering tip is the same but just has a screw fitting. Would it even make a difference if i swapped + and -?

    it says it is 5v 8w, would that still be good for using the 4 AA batteries? what about 18650? bad idea to use i guess since this is a “shortcutted” circuit? i might be wrong :)

  18. If it has 2 small diameter legs and a cap it may be one of Iso-Tips soldering tips. They are designed to work with a minimal amount of battery power and generate a ton of heat. You can’t use the old wattage comparison for the big irons because it doesn’t work. Go to their website they still manufacture 20 different tips and they still rebuild the old Wahl soldering irons and build new ones in the USA. Their tips have 7 components in them they are not a simple tip. They are designed so that is something goes wrong they won’t smoke your sensitive circuitry with the soldering iron like the standard soldering irons will. Thus the Iso-Tip isolated tip design.

  19. i just looked at iso-tip and it’s not one of those that i have, i can take a picture of it one of these days and maybe post a comment here with a link to the picture so you can see what it looks like, if you serach for zd-20u usb on google you should find it as first result, it’s blue transparent and a yellow ring near the soldering tip.

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