# Looking for a mold to repair Pos and Neg terminals on automotive batteries



## acrosteve (Jul 23, 2011)

Like the title says, I am trying to locate some forms or molds to repair battery terminals.

These would be placed on the battery and molten lead would be poured into the form to repair the defective terminal.



These seem to be hard to locate. I could have some fabricated as an alternative, so i could also use some input on material suggestions that could be used, but would not allow the lead to stick.

Sort of like this, but I have seen molds available before.
http://www.toymods.org.au/forums/tech-conversions/47950-reparing-melted-battery-terminals-posts.html



Thanks


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## Bruceter (Jul 23, 2011)

Is it a special battery that you cannot replace? It seems like it would be easier to buy a replacement battery than fix terminals on one.

Bruceter


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## acrosteve (Jul 23, 2011)

Nothing special other than the price of the batteries. This is for my work. We have several 4D and 8D batteries that are just fine other than one of the terminals. The 4D are $275 and the 8D are $325 each ballpark.

Right now I have over $2k worth of batteries I could save, and we have several each year that I could fix going forward.


We have cobbled a patched together here and there in the past, but I want a proper tool for the job. Whether that is purchased or custom made is yet to be determined.

In the past, I have seen one website with these listed, but they where foreign, and never could find a local dealer. Now, I can't even find the USA site.

http://www.duoregen.com/


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## NonSenCe (Jul 23, 2011)

intresting thing you are trying to do. 

whats wrong with the terminal? got a picture? is it totally destroyed, removed or partially there?

will the top of the battery withstand the heat? -most i have seen are plastic.. and they melt.

first thought is an larger version of the "pliers" people use/used to mold lead bullets in the old western cowboy style. (metal pliers with right shape mold for the led, clamp it over the rest of the terminal and then pour led.) but that is kinda too complicated to make.. more simple mold is better.. so..

second thought is an ceramic or heat resistant brick with right size hole drilled into it. and then an heat resistant cloth with the right sized hole for the terminal to pass but to cover the rest of top of the battery.. (lay the fabric first, then the heavy mold/brick on top of it then pour molten led and cool it then remove and see the results)

or some kind of 2 chunky pieces of metal, connected with screws to form a mold. (big chunk of metal. drill the hole in shape of the terminal, drill 2 or more screwholes from the side, then cut the mold into 2 pieces, check the size of terminal (might need to enlarge it a bit due cut away material) then tap the 2 screw holes add screws and you got an mold to use)

anyways.. both ideas kinda struggle with the molten led going where its not supposed to go. the heatresistant fabric (the kind they sell to put down flames at home/kitchen fires.. fireblankets or what they are called) might be best option limiting the heat damages and over flowing led.

---arent most battery terminals removable somehow (screw or nut or something?) can you drill a hole into the terminal and then tap it and add an screw or other terminal on it?


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## acrosteve (Jul 23, 2011)

They range in condition from...

not so bad







To not much left. You can see this one was patched once before, but not correctly.






I have seen it done, but never myself. There is a fine line between the right heat, and too much.

Here is some more information, but no pictures. http://www.evdl.org/pages/battpost.html



I like the pliers idea, as I was thinking of using a two piece mold if I fabbed it locally. If I cut it in half(or just bold two pieces together) before I bore the tapered hole, it will be just right. I like the idea of a gasket of sorts on the under side, but what to use that will be re-useable and the lead won't stick to?


Pretty much all I have to fix are batteries like those in the pictures. You can see that the structure under the actual terminal is stepped and would lend itself to a snug fitting mold on the bottom, without much need for a gasket possibly.


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## beerwax (Jul 23, 2011)

fishing sinker molds are just mild steel. hardwood is good for 20 or so castings. plaster of paris also works but must be fully dry. 

to get the new lead to stick to the old lead you have to heat the old lead up - whats in the battery is it horribly explosive ? 
the battery has plastic top - molten lead melts plastic - whats in the battery is it horribly explosive ? 


cheers


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## Norm (Jul 23, 2011)

beerwax said:


> whats in the battery is it horribly explosive ?


 
Hydrogen
Norm


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## LukeA (Jul 23, 2011)

You can use mostly anything for your mold if you put a layer of aluminum foil between the lead and the mold.


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## HotWire (Jul 23, 2011)

You could cut off terminals from batteries to be recycled, then screw them on with a bolt in a tapped hole. No heat. No explosion. You could mold terminals in self-made molds, then screw them on with a bolt in a tapped hole. Open flames around a battery can cause an explosion! Be careful.


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## DUQ (Jul 23, 2011)

I'm pretty sure they are replaceable. You just need some new posts and a terminal puller.


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## Lynx_Arc (Jul 23, 2011)

they make side terminal to top terminal adapters you could easily buy one and drill and tap a hole and screw one right on there.
http://www.amazon.com/Pico-0893PT-Battery-Adapter-Package/dp/B00030CPC8/ref=pd_sim_auto_1


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## TooManyGizmos (Jul 24, 2011)

~

There is a good reason why old batteries are totally recycled ........

You can't pour "hot" molten lead onto a "cold" post of lead ,
and expect it to bond and flow together as one solid unit .
All the lead involved must be molten to harden as one strong unit.
The part that was added will soon just snap off , if not immediately.

This is similar to the principals of a "cold" solder joint & bad connection.

I don't think anything like this would be reliable for re-sale .

I think you are wasting your time and efforts to persue this . IMHO

~


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## acrosteve (Jul 24, 2011)

Well, those are all good points, and the battery adapters seem to be the safest option, but I have concerns about the electrical connection when it is finished. These batteries see very high starting currents and are used in series.

About the hydrogen... I do realize that hydrogen is created when a battery is charged. But the batteries I would repair have not seen a charger for at least 6 months. So in my mind, the hydrogen would have dissipated - no?


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## Lynx_Arc (Jul 24, 2011)

If you could tap the lead properly and use light bulb grease when you screw in the adapter then the connection should be good enough for all but extreme current loads. what current loads do you need from the batteries?


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## FlashKat (Jul 24, 2011)

What is causing these terminals to get destroyed?
Buy new batteries, then take a proactive approach to prevent this from happening in the future.
You may feel that you are saving the company a lot of money now, but playing around trying to save money by temporarily fixing something that is explosive & corrosive with electrical especially running in series can cause serious damage costing a lot more than what you are saving.
Contact a battery manufacturer on information regarding dangers and repairs.


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## TooManyGizmos (Jul 24, 2011)

~

Ah...Men ......... +1

Well said , FlashKat !

~


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## Got Lumens? (Jul 24, 2011)

HotWire said:


> You could cut off terminals from batteries to be recycled, then screw them on with a bolt in a tapped hole. No heat. No explosion. You could mold terminals in self-made molds, then screw them on with a bolt in a tapped hole. Open flames around a battery can cause an explosion! Be careful.


 
This is what I was going to reccomend. You just need to change the battery cables end from a post connection to a (side) terminal connector. They are usually 5/16-18 N.C.. When cutting the old terminal off, just leave it raised about 3/16"-1/4". If in series this could be done to one of the straps between batteries.
GL


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## Lynx_Arc (Jul 24, 2011)

Got Lumens? said:


> This is what I was going to reccomend. You just need to change the battery cables end from a post connection to a (side) terminal connector. They are usually 5/16-18 N.C.. When cutting the old terminal off, just leave it raised about 3/16"-1/4". If in series this could be done to one of the straps between batteries.
> GL


 
would be easier to screw in side terminal post adapters and use the original cables


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## Got Lumens? (Jul 24, 2011)

Lynx_Arc said:


> would be easier to screw in side terminal post adapters and use the original cables


+1 You are right.
GL


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## Chicago X (Jul 24, 2011)

Lynx_Arc said:


> would be easier to screw in side terminal post adapters and use the original cables



This option may not be possible for multi-battery arrays, as in some Hi-Lows and forklifts.


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## Lynx_Arc (Jul 24, 2011)

Chicago X said:


> This option may not be possible for multi-battery arrays, as in some Hi-Lows and forklifts.


 
may have to grind them down to make for the same height and profile if space is at a premium. Sure beats having to swap cables going from a beat up modified battery to a new top post battery so you can have a side terminal cable on one instance and a top terminal cable on another one. The problem with modifying something to allow repaired parts to work is if you decide later to fix it with new parts like a new battery then you have to restore it to original. I tend to go with keeping things as original as possible unless your design change incorporates new parts and you have no intention of ever using the originally designed parts again.


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## Lynx_Arc (Jul 24, 2011)

I just did a search on google.... there are people who do recast battery posts. It requires a mold, a torch with a tight pencil flame and care to do it. I would recommend asking a battery seller locally if someone does them but for automotive purposes the fix I mentioned should be adequate because you don't require the huge currents forklifts and electric driven vehicles need.
http://ecomodder.com/forum/showthread.php/battery-post-repair-5578.html


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## acrosteve (Jul 25, 2011)

Good discussion.

I am not sure, but these batteries probably see in the ballpark of 1000 amps. It is over the 600A that my meter will read. Most are in a parallel/series configuration. 4 batteries producing 24v

I agree, in a perfect word that I could replace the batteries and not let it happen again, but we have lots of equipment with these batteries in it, and occasionally our mechanics do not catch a bad connection until it is too late. Thus the results pictured.

Also, changing cable end styles is not an option. These have to remain the tapered top post style.



I have been thinking of fabricating a couple of drill guides. These would index on the round area around the terminals. 1st one would be for a forstner type bit to establish a flat surface.

Then a 2nd guide to drill the pilot hole to tap the threads into. If I keep the surface flat, and the hole perpendicular, a proper contact interface should be assured.

Heck, overall that might be less work than getting out the torches and melting lead and all that.


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## Lynx_Arc (Jul 25, 2011)

Just set up a drill press and it should be easy to get things straight. I have seen many types of screw in posts some even made of metal instead of lead.


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## notrefined (Jul 25, 2011)

the damage appears to be melted terminals- from a bit too high resistance in a high current connection? I'm certainly not an expert, but that makes me dubious about the durability of any sort of repair short of recasting the post. the second image looks like it shows what happened when someone tried to use a screw to make the repair.


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## acrosteve (Jul 25, 2011)

Well, a drill press is not practical for this app. And i would still want a drill guide to ensure the hole is centered.

I think if I make the drill guides, i can also do the repair in the field, without removing the 140lb battery from the machine.


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## Diesel_Bomber (Jul 25, 2011)

In my experience, a lead acid battery that's been sitting for six months is probably shot. I would throw such a battery on a charger for a while, monitor voltage, then try and pull some current out of it, and see if they're worth saving at all. Would be a shame to spend time/money on it only to find it's trash anyway. However, these toasted batteries could be perfect sacrificial donors to perfect your battery terminal repair technique on.

As for the terminals themselves, I lean towards drilling + tapping a hole and replacing the terminals w/ screw in side mount conversions. Past that, building a set of mold pliers wouldn't be difficult, including a clamp to hold the pliers closed. I haven't done this before, but my steps would be:

1. Grind off anything that isn't shiney clean lead.
2. I'd clamp the mold over what's left of the terminal.
3. Melt the lead to be poured
4. Use a torch to heat the remains of the terminal so that there is a small pool of liquid lead on the top of the terminal. The clamped-on mold will help keep the heat away from the plastic of the battery.
5. Pour in replacement lead
6. Hope/pray that anything that shouldn't melt doesn't.

I think I'd also make the mold fairly heavy, for heat sinking capabilities. More heat absorbed by the mold + slowly released while the molten lead cools = less heat into the plastic of the battery. I'd pour the lead when it's just a liquid, heated as little as necessary to do the job. And of course test this on batteries that are already trash, to refine technique.

Good luck.

Edit: Insert standard disclaimer here. You are responsible for your own actions. I take no responsibility for any injuries, damages, or losses of any kind whatsoever caused by following my advice.


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## acrosteve (Jul 26, 2011)

Well, here is my prototype.

Just a piece of 2x4 I had laying around. And a terminal from a busted battery.

Just a slight amt of drilling after cutting off the term with a cutoff wheel.






Finished.






This is what will hold it in place.











My 1st modification will probably be to get a piece of square stock, bore a hole in it and then install it in the wood for a better bushing for the 19/64 drill bit I am using.






I did not have any side post adapters yet, but will get some this morning. I wonder what they would torque to into lead? Threads are 3/18-16

I was planning on using some "No-Ox" type of corrosion preventative since I have it already. But what about some sort of JB weld - would any of their products be conductive enough?


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## Lynx_Arc (Jul 26, 2011)

I don't know any good conductive epoxy off hand. If your corrosion preventive isn't a grease I would recommend something like light bulb grease on the threads as it is conductive. Perhaps something like silicone caulking after it is done to seal the seam.


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## Got Lumens? (Jul 26, 2011)

I would use the JB weld for mechanical only. I feel it is one of the best on the market. Used it to fix a worn out fan clutch, had run for several years without failure. 

With the high currents you are using, I would use the tap existing and screw on replacement posts, having checked the batteries prior to doing so as stated by Deiselbomber. Pouring a new post would seem second best fix with the associated risks. There is also the possibility that the lead you melt on to fix, may have slightly different composition, which may lead to the fix expanding and contracting at different rate which could contribute to a high resistance open.

GL


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## beerwax (Jul 26, 2011)

hi acrosteve.

so there is enough meat in the remains of the terminal post to sink bolt deep enough to secure a new teminal ? is that what your pictures are showing? 

you do not need to rely on the securing bolt to carry the current. lead is quite soft and so if pressed and held together the lead will deform sufficiently to give a good electrical connection. just clean the lead to shiny immediately before bolting together. if the 2 surfaces arent perfectly alligned the bolt will flex slightly and the lead will deform allowing a perfect join. 

on the downside you then have a bolt inside the battery perimeter , and if it heats up and destroys the post inside the battery perimeter this would be bad. and this could happen if the post extension and bolt were to undo slightly so the bolt was thencarrying the current. 

looking at you photos can the remains of the old post be pulled out, specially now you have a nice threaded hole there. maybe they are just pressed in. that would allow a manufacturer to supply the same battery with different style posts . and make your job straight forward. cheers


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## acrosteve (Jul 26, 2011)

I agree, I want the lead to lead contact to carry the current. I am looking at a couple of different adapters. I will post some pics of them tomorrow. The ones I got today are no good.

This battery does have a very substantial post structure. I could drill and tap a hole over 2" deep if I wanted to. As it is, I just went about 3/4"

I am still looking for a good torque spec, but have not found anything yet.


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## Got Lumens? (Jul 26, 2011)

acrosteve said:


> I agree, I want the lead to lead contact to carry the current. I am looking at a couple of different adapters. I will post some pics of them tomorrow. The ones I got today are no good.
> 
> This battery does have a very substantial post structure. I could drill and tap a hole over 2" deep if I wanted to. As it is, I just went about 3/4"
> 
> I am still looking for a good torque spec, but have not found anything yet.


Steve,
I would contact the battery manufacturer and not rely on specs found somewhere else. They would be the ones that could answer that question about torque and the grade of the lead used in thier battery posts. A word of caution, they may decide not to disclose the torque information to you if they feel that it was going to cause any liabilties on thier end.
Look forward to seeing your posts (pun intended).
GL


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## Diesel_Bomber (Jul 26, 2011)

You have a sacrificial donor, so torque it down until something strips. Don't torque that far on the good ones.


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## Got Lumens? (Jul 27, 2011)

Diesel_Bomber said:


> You have a sacrificial donor, so torque it down until something strips. Don't torque that far on the good ones.


+1
Using a torque wrench of course


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## acrosteve (Jul 27, 2011)

I have two options for terminals. I am a little dissapointed that the ones with the stud are so short. Only about 3/8"





They will only take 15 ft lb, which I thought was a little low.


I put a stud in the other one and got 3/4" of thread engagement and got about 23 ft lb. So I think that I am going to go that route as I go forward.


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## Got Lumens? (Jul 27, 2011)

acrosteve said:


> I have two options for terminals. I am a little dissapointed that the ones with the stud are so short. Only about 3/8"
> They will only take 15 ft lb, which I thought was a little low.
> 
> I put a stud in the other one and got 3/4" of thread engagement and got about 23 ft lb. So I think that I am going to go that route as I go forward.



The studded one you have are adapters for making side post terminal battery to accept round post cables, but as you have indicated they may not be adequate for your application. A regular automotive starter draws less current than your setup. The one you put the stud in seem like they should work:thumbsup:
Look forward to your followup posts.
GL


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## Diesel_Bomber (Jul 28, 2011)

If you have access to a lathe or machine shop of some sort, you could turn your own terminals out of brass or copper. Either run allthread through the middle or, what I'd do is cut threads on a shaft you've left sticking out of the new terminal.

I'd also like to add that 99% of the time, prevention is faster/cheaper than repairs. Having a mechanic walk around and check the battery cables of the equipment and fix any developing problems every week or two wouldn't take much time, compared to repairing broken stuff.


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