Soldering Iron Power

Discussion in 'General Electronics Chat' started by Wiky5, Oct 18, 2016.

  1. Wiky5

    Thread Starter New Member

    Sep 3, 2013
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    Hi,
    I want to solder starter motor wires to their battery connectors and to the ring terminals on the other end, but my 40w soldering iron isn't up to the task: it can't heat the metals even close to what's needed so the solder does not melt at all. What power do you believe the iron should have for this task? Is 200w too much or still not enough?
    This might seem an odd idea, but i live in a really arid place where lots of dust fly around, which gets inside cable junctions and fouls the contact between wire and connector, slowly making the starter harder to turn up to the point that a new wire is needed. The fact that the farm's engines end up covered in oil for no apparent reason does not help either, as dust is quite eager to stick itself on hydrocarbons.
    Soldering smaller/"normal" wires to sheet metal would also be nice, though I guess more power is required for the hefty copper wire and bronze connector.
    Thank you very much for your answers!
    Best regards,
    W
     
  2. #12

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    I like a 2 speed Weller 250 watt soldering gun.
     
  3. GopherT

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    Cover the battery terminal in any standard grease before tightening down the connector.
     
  4. Wiky5

    Thread Starter New Member

    Sep 3, 2013
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    @#12, Awesome gun! It's a shame they don't sell them in Argentina... (postage/courier takes months to get here due to dumb regulations)
    I guess I'll look for something with that power capacity.

    @GopherT, grease cured the symbtoms at first, but in the end it failed at about the same time as non greased connectors.

    Thank you both for your answers
     
  5. tranzz4md

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    Apr 10, 2015
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    Soldering is an older procedure than electrical soldering irons. That Weller is a good gun, but no problem, use an old time soldering iron.

    For what we're talking about doing, you might want something about a pound (500g). I'm talking about an item that's usually made of copper (but they were called "soldering irons"!), would be rectangular, about 1"x1"x4" (20x20x100mm), with one end tapered on all 4 sides (maybe a 60°taper), and have a steel tang going to a wooden handle. You heat it with a flame to get it several hundred degrees, and go do your work with it.

    ALL SOLDERING DEMANDS EXTREME CLEANLINESS AND FLUX. If you use an old iron, clean it shiny before and after heating it. To (re)clean it once it's hot, you need to use a very quick rub with a file or coarse clean stone, then solder with lots of flux. This is flux in a tin can. Coat it with solder, and have a very damp COTTON cloth to wipe it with from time to time. You'll use lots of solder and flux, that's just how it goes. It's possible to get it too hot, and if your shiny solder coating burns up on you quickly it's too hot.

    In any case, touch that hot iron to your workpiece to heat it, carefully melting a small amount of solder to help heat transfer, and dabbing flux at the edges of that molten area. Of course your workpieces need to be shiny virgin metal clean -IT'S NOT POSSIBLE TO HAVE YOUR WORKPIECES TOO CLEAN!!!- then coat (at least) the bonding surfaces with flux.

    Using the old style big irons can sure get sloppy, so lay out your work so all that heat, flux, and solder overflow won't cause trouble, burns, etc. You may need to clean up the workpieces after soldered and cooled with a coarse file or 4-in-hand.

    To keep heating that iron use a propane or MAPP torch on the body of the iron, pointing away from the clean, shiny, tinned tip.

    Maybe there's a YouTube showing it.
     
  6. #12

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    Now that you mention it, I did buy a propane torch kit with a soldering iron attachment, a very long time ago. I almost never use it because it's big enough for car battery cables. It's rather difficult to regulate. It gets too hot too easily. Almost impossible to get the flame small enough. You pretty much have to start with a cold tip and be waiting with the solder as it passes the correct temperature. You can't do 2 in a row because the temperature overshoots so quickly. You do one, then turn it off, let it cool, and re-start it to do the second cable.
     
  7. Wiky5

    Thread Starter New Member

    Sep 3, 2013
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    @tranzz4md cool! I guess I'll try with an electric soldering iron first, as that seems to be more complicated than necessary. It's great learning about the stories of these things we take for granted.

    @#12, I thought about a propane torch also. It might be good for farm use and when electrical isolation is needed. I want to make a 12vdc-12vdc isolator, but that seems to be one of those endlessly postponed projects of mine...

    Thank you very much for your answers!
     
  8. tranzz4md

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    Apr 10, 2015
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    Old timers, and others that have used the old style irons still prefer them for some tasks, the biggest complaint is the weight, but the even, steady heat is fantastic.

    I had a tip for a torch like #12 spoke of, but like his, it was with an older torch. All I've seen that fit on a torch are too small! I now have a "push button" torch (one with a piezzo spark and push valve together), which would make that work a lot better.
     
  9. tcmtech

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  10. ian field

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    I've never seen soldered starter motor wires on a vehicle - probably because they get hot and unsolder themselves. Solder also wicks into the strands making it a rigid cable that's prone to fatigue - that's probably how it loses cross section and loses current capacity till it gets hot enough to melt solder.

    If you don't want to pay for an expensive ratchet crimp tool - some auto accessory shops sell connectors with screw down cable clamps. You could also look in a welding supplies shop for replaceable cable lugs.
     
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  11. tcmtech

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    If they are getting that hot in the time it takes to start an engine or even run the battery dead there is obviously a connection problem. :rolleyes:

    A properly sized and made solder connection for a high current application is no different than a smaller low current one.

    I for one have been making soldered battery cables for years and have never had a solder or cable related issue from it.
     
  12. ian field

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    The TS said starter cable - you might get away with soldering the low current bit.

    Years ago; some were brazed - now crimp or clamp is more usual.
     
  13. tcmtech

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    Yes. What's your point? o_O

    I solder heavy cables for starter systems and other high current applications all the time. Been doing it for over 20 years now and have yet to ever have a soldered connection go bad or give me trouble. In fact I do it often enough to justify buying rosin core solder in 1$ .125" dia spools 2 - 3 at a time. http://stellartechnical.com/wiresolderforindustrialsoldering.aspx If you need some.

    The last large set were for our AC 7050 tractor which I upped to 4/0 cable being it can pull around 1200 amps or better when cold.

    The most recent ones were 2/0 for our old International 560D.

    Crimping only became popular because it's faster, easier and cheaper than soldering for large diameter high current cable applications. Not necessarily better.
     
    Last edited: Oct 19, 2016
  14. #12

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    I have to go with @tcmtech on this. In all my years, I have never had a soldered cable go bad and have to do it over.
    I hadn't thought about it until now, but that's the definition of a good method...you never have to think about it because it has never failed.:)

    I've had musicians jerk the cable out of the connector, but it wasn't my work that failed, it was the strain relief system in the connector. Who was that who liked to swing the mic in big circles? Roger Daltry? The only time I cussed a customer was when they showed up at a gig with a cord they knew was bad and didn't turn it in for repairs before we arrived at the job.:mad:
     
  15. tcmtech

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    The only damage I have ever seen done to properly made solder connections came from physical abuse or the terminal or cable material it was connected to having degraded over time. The solder and the actual cabling where the solder was itself never gave up at the solder joint without considerable external influences that were no fault of its fabrication. ;)

    Of the many cable connections I have seen that went bad every single one was either due to improper soldering ( never got hot enough to wick the solder in due to wrong type of solder or no/wrong flux was used or the soldering was attempted long after permanent irreversible corrosion had set into the parent joint materials) or physical degradation/abuse breaking the terminal off or the cable just above the solder joint. The properly done solder joint itself never gave up and caused the problem but the terminal or cable just beyond the solder joint was what did.
     
  16. Wiky5

    Thread Starter New Member

    Sep 3, 2013
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    @ian field if the cables were to warm up so much on startup, they'd melt the plastic insulator with potentially catastrophic results if the battery gets shorted due to that insulator melting. Connections do warm up when they are badly done or dirty, removing volts from the starter and forcing me to use unconventional methods to start the engines. Deodorant in the air intake of a diesel engine yields good results.
    The battery connectors on my cables are bolted onto the cable, except for one original cable on my pickup that has a lead connector which looks like it was molded with the abnormally large wire in, and the ring terminals are all crimped (nice way of saying "hammered on" really).
    @tcmtech I tried heating a battery connector with a stove, but it wouldn't get hot enough to melt solder, or maybe my impatience did not allow it. Next time I go to the farm I'll try with a propane torch I've just bought, if that fails I'll borrow my neighbor's lpg torch. Considering what @tranzz4md said, maybe I'll buy new connectors and wires, as probably filing, eating with acid and stripping more wire wasn't enough.
     
  17. tcmtech

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    As I commonly point out to people on the old farm equipment forums, "There comes a time where you just have accept that you need to replace the cables, period. They are a consumable components that eventually do wear out for a number of reasons."
    That where all of my heavy battery cable rebuilds and outright new cable manufacturing projects come from. Terminals, lugs, cable ends, cable wire all gets old corrodes, breaks down and needs replacing.

    If you're at that point you think you have to solder your terminals/cable ends to the battery itself, or anywhere else for that matter, it's time to replace things. Which, BTW, if they are so corroded as to not make and hold proper connections they are also way past the point that any solder is going to stick to them well enough to do anything gainful. :rolleyes:
     
  18. GopherT

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    Battery terminals for high current connections are not soldered if vibrations are possible. The undefined end of the solder joint as it wicks up the stranded cable (even wicking up the insulation) causes weak spots and all movement eventually torques on one strand (or a few strands) and those strands eventually fail. Then the next weakest strands absorb the vibration energy and so on and so on and so on until you have a high-resistance connection that fails. Crimping/clamping seem to be the preferred connections. Also, an additional cable restraint about 10 cm away from the connection is further help to minimize the strain/stress caused by vibrations and other movement on the crimped connection.
     
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  19. ian field

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    I said that - and pretty much got flamed for it.......................
     
  20. GopherT

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    Ah, I only read a few at the beginning and a few at the end. For what its worth, I agree with you.
     
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