Battery repair? Help needed

Discussion in 'General Electronics Chat' started by Jacob J, Dec 15, 2011.

  1. Jacob J

    Thread Starter Active Member

    Jun 18, 2009
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    Hey all

    I have a boat on which I have four batteries, two sets of 12v's in series and then in parallel, so the whole system runs 24v's.

    The problem is that one of the terminal on one of the batteries have been broken off. So the terminal is in level with the battery-casing itself.

    My question is now, can I take a drill a few millimeters smaller than the core of the broken terminal an drill a hole of lets say 1 centimeter and then put a iron rod into the hole with a snug fit?

    Is this a no-no repair or is it possible and safe to do?

    /Jacob
     
  2. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
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    Maybe. How about a picture of the battery ( with something to show scale )? How much current do you plan to draw? Switch the metal to copper, easier to work with better conductor. Beware if lead acid battery, you might liberate acid.
     
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    Just buy a new battery..
     
  4. Jacob J

    Thread Starter Active Member

    Jun 18, 2009
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    Well I dont quiet know how much current, but I had some start-cables that could draw 120amps and they couldnt start the engine, I put two sets on and then it started up. So I guess more than 120amps. If the iron rod I am putting into the broken terminal is 8 millimeters, dont you think it will work fine? I could try to find some copper in that dimension, but I am not quiet sure where to look for it. It is a lead acid battery.

    I was by a automobile workshop and he told me that I should drill in it, because the battery could explode... Is there any truhf to that?

    Is 1 centimeter enough in deept? How long is the terminal in such a battery?

    I can't take a picture atm because the battery is on my boat, but I will see if I can find a picture of it somewhere on the net.

    A new battery would be ideal, but such a battery runs for around 400 dollars, so its a bit for me as a student..
     
  5. Jacob J

    Thread Starter Active Member

    Jun 18, 2009
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  6. PackratKing

    Well-Known Member

    Jul 13, 2008
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    I did the same with a brandy-new battery once, dealer told me I was S.O.L.............

    Being a packrat,:D I had some 5/8 thinwall brass tubing, sanded off the chrome, sharpened one edge, and cut a 3/4 inch piece....... drilled a hole gingerly down the remains of the terminal on the battery, tapped it 1/4 x 20, installed a cut off grade 3 plated bolt - nothing fancy - and screwed that into the battery as tight as sanity would let me , leaving 1/2 inch above grade. Tapped the sharp edge of my "mold" into the remains of the lead on the battery so hopefully it wouldn't leak.........and fluxed it well.

    Melted the piece of terminal and a couple fishin' sinkers for good measure in a campbell soup can, and poured a new terminal.......get one of the battery terminals that doesn't need the normal taper.
    Dang if it didn't last until my Falcon rotted off the wheels several years later. Good luck.....it works
     
  7. MrChips

    Moderator

    Oct 2, 2009
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    That's what we like to read on AAC, guys who can turn a bad situation around using imagination, improvisation and resilience. Good work. Pack Rats Unite!
     
  8. t06afre

    AAC Fanatic!

    May 11, 2009
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    How in earth did you manage break of the battery pole. Did you use a big hammer ;)
    A bi product of lead acid battery charging, is oxygen. So perhaps it is best to use a hand drill. However without any picture it is hard to say. But I think you plan will give a contact point with to high contact resistance. And that may be unwanted during high current draw. Like starting the engine. It could be a risk. My intuitive gut feeling say no do not do it.
     
  9. Crispin

    Member

    Jul 4, 2011
    88
    2
    Done the same as that to batteries and had great service from it. I had a bit protruding from the case, drilled some cross holes so the mould had something to hold onto and poured the new terminal.

    Save yourself from buying a new battery and have 3 old, 1 new ;)
     
  10. t06afre

    AAC Fanatic!

    May 11, 2009
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    Molding a new pole may work. Just remember to clean of any fat and oxidation before molding. Use a stainless steal wire brush. To remove oxidation. The use use some isopropanol to clean of dirt/grease/oil. Then mold
     
  11. crutschow

    Expert

    Mar 14, 2008
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    3,245
    If you open the vents and blow some air into them, that should flush out any hydrogen and minimize any chance of explosion.
     
  12. Jacob J

    Thread Starter Active Member

    Jun 18, 2009
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    Do I have to mold a new terminal? On the other battery I have there is just two holes in it and they are taped so I just screw in a bolt with the cabel between and it works great, so I hoped that I could just drill the hole and put in the iron rod (snug fitted) it would work. The rod is taped, so I can screw the cable onto the terminal, like the other battery I have. Isnt it enough or do I have to mold a terminal?

    I think the venting of the cells is a good idea and I will do that before I drill.

    Any other suggestions before I proceed?
     
  13. MrChips

    Moderator

    Oct 2, 2009
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    I suppose the purpose of the a new molded terminal is to build a battery post so that you can attach a standard battery clamp. If you have screw terminals then there is no need to build a new post. It depends on how much depth you have left. A photo of the damaged post versus a good one with the cable connected would be useful for us to judge. If you do not have a lot of depth, it may be helpful to build up the damaged post by pouring hot lead into the hole before you create a new stud connection. Just some thoughts. I don't know if there will be enough heat capacity in the poured lead to create a new bond with the existing lead. Any thoughts from others?
     
  14. Jacob J

    Thread Starter Active Member

    Jun 18, 2009
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    Well the rest of the terminal is in level with the battery casing, so 4/5 of an inch is broken of the terminal. I think I will drill 1 cm down into the remaining rest of the terminal.
     
  15. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    You are asking about repairing a sub $300 battery for a boat costing from the thousands of dollars on up to the sky is the limit.

    It is not worth risking repair. The worst that could happen is you burn down a boat trying to save a few hundred dollars on a battery that is probably due to be replaced anyway.

    The least bad thing that might happen is a failed engine start, failed nav equipment or failed VHS when you need it in a critical situation.

    Get a new battery. If you can't afford to properly maintain a boat then you shouldn't be owning it in the first place. Anyone knows they are holes in the water that you pour money into.
     
  16. Jacob J

    Thread Starter Active Member

    Jun 18, 2009
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    Hmm the battery is fine as it is and has been running and starting the boat very well until now. I can't see anything wrong in saving some money, if I get a battery out of this procedure that works just as well as one with both terminals intact.
     
  17. MrChips

    Moderator

    Oct 2, 2009
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    Why waste a perfectly good battery? My vote would be to go with your planned repair. Install a stud, as large as space will allow and bold on to the stud with the largest gauge eye-terminal and cable that will fit.
     
  18. PackratKing

    Well-Known Member

    Jul 13, 2008
    850
    215
    The primary consideration in pouring a new terminal ; I had no clue how deep into the terminal I could drill and get away with it. When the hole was deep enuf to run 8 threads w/ bottoming tap, I considered it lucky.

    Just placing a stud into the lead, would be shaky at best, 'cuz how much torque can one put on 8 threads in lead....?....not a whole lot......

    The only other considerations, were how well would the lead melt together, and how long before the effect of electricity through dissimilar metals w/ the plated bolt encapsulated in the poured terminal came back to haunt me ??
    I'm thinking that a stud would have rotted in short order, and make a connection prone to heating / sparking when contact began to break down.

    I do a treatment with the factory side-terminal monstrosities...when I get stuck with them........the material in the terminals is of decently sterner stuff, so I do torque a stainless stud into them, and crimp and solder eye-terminals to any connecting cables.
    I wouldn't spend your money on side-terminals. :D
     
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