How can I make a 3 AA rechargeable batteries powered device last longer?

I got a battery powered plastic cutter ( the batteries were used to heat the blade) and turned it into a soldering iron. I thought it being really smart of me, but the power of my 2700mAh batteries is severely not enough to melt the solder for long. Ater 15 minutes' work it simply stops melting, while the batteries are still fully charged, so my charging device simply turns the green light on and refuses to charge them. HELP!!!  

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The BEST way is a propane powered iron, for the kind of duty you say you want. They are powerful and easy to use in the field.
Actually, they're butane powered.
Picky, picky. "Lighter gas" then.
Well, I just wanted to save him the embarrassment of walking into a hardware store, asking for a propane soldering iron, and being directed to the plumbing aisle where they keep the propane torches.
Ah, you're correct. My mistake, sorry gruffalo child!
gruffalo child (author)  jeff-o6 years ago
That's all very nice, but somehow my parents don't like anything "Lighter gas" powered, so the battery thing was my solution to avoid it. (I even use an ethanol burner instead of a Bunsen burner despite the fact its very hard to get ethanol here, or anywhere, I suppose, but I don't know why it is safer).
Ah, too bad. Well, can you get anything like the Cold Heat soldering iron where you are?
gruffalo child (author)  jeff-o6 years ago
Wow, but "if it is to be used on electronics, one should be well aware of how the device works and the sensitivity of components being soldered" and "the tip is very fragile", so even if I find it anywhere, it'll cost loads and loads of money (I earn nothing), and I will either brake it on the first day, or be too afraid to do anything with it (not exactly my idea of fun).
Well, I'm not sure if it's *that* fragile, but you're probably right about the cost. If you can't get it locally, it'll probably cost a bundle! I say you should try to convince your parents to let you get a butane powered soldering iron. They heat up fast, and last for hours. They are safe to use - the flame is not exposed like on a lighter.
Technically they don't even HAVE a flame, they decompose the butane on a catalyst, releasing heat.
Cool! Is that the case for all of them, or just the higher end models? I've seen some "convertible" models in which you can remove the soldering tip to get a regular torch - in that case, the torch just heats up the tip.
All the one's I've seen are catalytic.
OK, good to know. :)
rickharris6 years ago
You need to arrange an external power supply that can provide the required current for as long as you need it.

HOWEVER as this is something that I guess is intended for intermittent use and you have converted it to be used for much longer periods as a soldering iron it may not last that long.

gruffalo child (author)  rickharris6 years ago
Thanks, but the problem is that I need a soldering iron that is able to function without a mains power supply for at least an hour of work ( it doesn't have to be on all that time as it heats up quite quickly). I badly need it on various in- the-fields summer school, where you are supposed to do Physics experiments, but the power supply is one or two half-dead sockets and they don't allow you to sit there and solder for long, or even use them for something more power-consuming than a phone charger (for example making tea is a problem :) )