Joining NiCd batteries - conducting glue

Discussion in 'General Electronics Chat' started by boblalux, Oct 9, 2016.

  1. boblalux

    Thread Starter New Member

    Oct 16, 2015
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    Joining NiCd batteries - conducting glue
    I have to join 12 1.2V NiCd batteries to form a pack of 14.4V. As I cannot purchase tagged batteries (the direction of the tags is not correct for my pack), the solution would be to solder each of these tagged battery together. I have tried this, but it's just too difficult to solder.
    Question: Can I use a conductive glue, which will accept up to 1 amp, and exhibit a very low resistance? If so, must I buy relatively expesive silver/epoxy glue, or can I make it by mixing carbon powder:Epoxy at 1:1?

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    Last edited by a moderator: Oct 9, 2016
  2. Papabravo

    Expert

    Feb 24, 2006
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    If you have the time and the energy -- why not run the experiment. I've never heard of such a thing, but that really doesn't mean much these days.
     
  3. hp1729

    Well-Known Member

    Nov 23, 2015
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    Soldering or gluing them sounds so permanent for a part with a high expected failure rate. would battery packs be better?
    Re: carbon and epoxy
    I don't think so. J-B Weld glue has metal in it but doesn't conduct. Is spot welding your own tags on an option for you?
     
    Last edited by a moderator: Oct 9, 2016
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Can't you solder extension leads to normal tagged cells?
     
  5. tcmtech

    Well-Known Member

    Nov 4, 2013
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    I solder leads to NiCd and NiMH batteries all the time when rebuilding cordless tool battery packs.

    The trick is to clean the spots where you want to solder to with an abrasive so that takes the surface plating/oxidation off.

    I use my Dremel with one of the sanding drums to do the clean up and a 150 watt buzz gun type heavy duty soldering gun to get enough heat into the work area fast so that it doesn't have time to heat soak the inner cell components.

    Simple, easy and reliable once you know the correct method.
     
    Last edited: Oct 11, 2016
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  6. hp1729

    Well-Known Member

    Nov 23, 2015
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    http://www.mgchemicals.com/products...epoxy-moderate-cure-extreme-conductivity-8330

    Conductive glues look like they can handle the job at 0.001 ohms per cm. If this is just a one-time thing the price would not be so bad but for production, yes, it would seem to be costly. For production mold the battery socket into the case.
     
  7. boblalux

    Thread Starter New Member

    Oct 16, 2015
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    No, can't spot weld as I don't have the equipment.
    It's just a battery pack I am trying to assemble - 12 NiCd Sub-C cells to be joined together, (to give 14.4V) to fit into the pack holder of a Accu-drill, according to an exact configuartaion. To buy the original replacement I will have to pay half the price of the drill.
     
  8. Externet

    AAC Fanatic!

    Nov 29, 2005
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    Half the price of the drill...not that bad. That is usually a wallet squeeze of 80% the price of the drill.
    Forget about glue; but if you succeed insisting on it, let us know which glue worked.
    Wrong tabs orientation can be corrected folding the needed tab as 'origami' towards the desired direction.
    Or, simply, solder wires between tabs. Perhaps AWG 16
     
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  9. hp1729

    Well-Known Member

    Nov 23, 2015
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    Do let us know how it comes out. A lot if us may be there some time in the future. Glue wires to the batteries?
     
  10. tranzz4md

    Member

    Apr 10, 2015
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    Don't know your location, but rebuilt packs are probably commercially available. There was an outfit here in the USA, Pennsylvania I believe, that did them all; tools, laptops, medical, UPS, you name it, and had lots of stuff ready to go within 3 days or so, and I found out about them from a very pleased customer, and believe I also did a laptop battery with them at least once.

    If you're in Europe, I'd bet there's a counterpart, I believe in the UK.

    On your own though, tcmtech's method is precisely how to do it, and it took me years to find that out (but those soldering rules are so simple!).
     
  11. debe

    Well-Known Member

    Sep 21, 2010
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    Thanks for that tip TCM. Just soldered leads to some Li-Ion batterys that were giving me grief. Once cleaned soldered easily, but it needs to be done quick.
     
  12. tcmtech

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    Nov 4, 2013
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    Yep. Some place I have a old Craftsman 175/250 watt buzz gun that was super for that fast high powered soldering work but dang if I can find it any more. There's a big box or two of tools, equipment, parts and other stuff that got put someplace 3 - 4 years ago and I cant find to save my life. :mad:
     
  13. MrAl

    Well-Known Member

    Jun 17, 2014
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    Hi,

    It is hard to recommend soldering batteries of any kind, but if you have to then use a good solder such as silver bearing solder or something like this. This kind of solder wets fast and doesnt require much heat and comes in very thin gauge wire.

    The conductive glues/epoxies etc., are about 100 times more resistive than solder, but if applied in a thin layer should provide good enough conduction. However, there are other properties of materials like this that need to be considered such as the strength and elasticity.
    Even solder is not considered that strong and so recommended assembly procedures always reflect that shortcoming, but some conductive glues are not very strong at all and so need to be used with care as to how the parts are mounted before and after application.

    For example, if you glue 10 cells together end to end with no other support, they will probably break apart when handled a little now and then. If they are mounted in some kind of support first though then the connections may survive for a longer time. So a good mounting procedure is a good idea. A battery holder of some type would probably work better though, and they make battery holders for all kinds of battery cells.

    That being said, there is a cheaper version of the conductive glues called "Wire Glue". This stuff is about 3 or 4 dollars USD and has reasonable conductivity although most likely not as good as the silver stuff because it is made with carbon particles. The consistency is like mud until it hardens. Thus stuff is no good at all though without proper mounting of the parts because it breaks apart too easy. It does work when used right though.

    All being said and done, if possible i would use battery holders before soldering or glue of any type. Remember that high heat can quickly ruin a battery in a way that you wont know about until it fails later because the damage occurs inside where you cant see it. The separator of a modern cell is quite thin too so is easily damaged, so proceed at your own risk :)
     
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  14. boblalux

    Thread Starter New Member

    Oct 16, 2015
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    <<<All being said and done, if possible i would use battery holders before soldering or glue of any type. >>>
    That's just the problem: the 12 batteries have to fit in the handle of the power drill, to an exact configuration. No space for a battery holder, which I agree, would be the best solution.
    Otherwise, thanks for all the info.
    Bob
     
  15. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Ordinary tin-lead solder melts at 183°C. It is hard to beat that without using a "low-temp" solder with bismuth. I just use tin-lead solder when I have soldered batteries. One hint is to use copper braid rather than wire for the connections. It lays flatter and stays somewhat flexible. You can buy braid at electronic supply houses and many hobby shops. For the small amount you need, braid from a shielded cable (be sure it is copper or tinned copper) can be flattened and works fine.

    John
     
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