battery post came off !

[grafozz]

whilst shortening the windlass cable run (by 7 metres ) I overtightened the battery post , which has a small /4 mm ? , bolt holding it to the battery body and it snapped , inside the battery lug . ah , problem ! how can the broken remainder of the bolt be extracted ? it seems a bit lightweight fitting a battery post to a big heavy battery using a little 4 mm bolt ? I would be grateful for any ideas ,please , grafozz .

[William_H]

I am having a bit of trouble imagining what it all looks like. Batteries I am familiar with have either a round post with a clamp or a flat lead post with a bolt and nut through a hole. If it is a flat lead post with a 4mm brass bolt embeded and this has snapped off I would be fashioning a clamp of some sort ie 2 brass plates bolted together but with a gap between that the post can slip into. Clamp the 2 bolts together to get a good connection and a lug under one bolt.
I imagine any stud into the lead has been cast into the molten lead. Lead would be pretty hopeless to tap into with any sort of reliable thread. Lead too soft) So good luck post a picture if you want more ideas. olewill

[Thistle]

Make a mould for a replacement battery post and fix it in position. Get the carbon rod from a dry cell - a big D cell is ideal. Attach this via a length of thick wire and big crocodile clips to the other terminal. Get a length of rod solder. Wear gloves and dark glasses. Use the carbon rod to strike an arc on the post to be repaired. Melt the solder rod with the arc and fill the mould with melted solder. Carry on and use your new battery post. Job done!

[Sneaky Pete]

Like Thistle says make a mould of the terminal, instead of using solder which is lead and tin just use lead on it's own. It is the same as the terminal and can be melted over a gas stove melts about 230*C Plumbers merchant or scrap metel merchant may have lead.

[MrCramp]

Make a mould for a replacement battery post and fix it in position. Get the carbon rod from a dry cell - a big D cell is ideal. Attach this via a length of thick wire and big crocodile clips to the other terminal. Get a length of rod solder. Wear gloves and dark glasses. Use the carbon rod to strike an arc on the post to be repaired. Melt the solder rod with the arc and fill the mould with melted solder. Carry on and use your new battery post. Job done!

Isn't the battery likely to explode in the procces??

[mitiempo]

I'd think twice before striking an arc over a battery - especially in a closed space like a boat. Might be your last act.

[grafozz]

thanks all , I probably have not explained this too well .... the post was bolted on to a lead base which is cast into the battery case , so I still have the post in perfect shape.with a bolt sheared off inside it ,and the rest of the bolt sheared off in the battery case / lead . so I still have the lead base to fix on to . the replies give me the idea that it may be possible to melt the lead post back on ,but how to do that safely ?
I dont fancy welding gear near the battery, as suggested ,too risky methinks ! I have an old battery to use for spare lead posts .

[JohnTH]

Irons soldering electric?

73s de

Johnth

[pampas]

Take the battery to a auto electrical repair shop who May have the mould but I think that this battery may well be scrap, Do not attempt any repairs yourself unless its by a solderless method.

[boathead]

thanks all , I probably have not explained this too well .... the post was bolted on to a lead base which is cast into the battery case , so I still have the post in perfect shape.with a bolt sheared off inside it ,and the rest of the bolt sheared off in the battery case / lead . so I still have the lead base to fix on to . the replies give me the idea that it may be possible to melt the lead post back on ,but how to do that safely ?
I dont fancy welding gear near the battery, as suggested ,too risky methinks ! I have an old battery to use for spare lead posts .

It's already been said, but i sense a wee bit of concern. Get a big spoon or soup ladle, put the broken terminal in it, heat over cooker/burner. Use a jubilee clip as a mold placed over the battery terminal base, pour in melted terminal, leave a few moments and remove the jubilee clip. Sorted........ I have done it many, many times with trucks, it's no problem. Perhaps I would add, remove the sheared bolt from the terminal before or during melting, and perhaps if available off an old battery, cut a bit off extra lead to for good measure and to replace volume taken by the bolt, ignore the bit in the battery terminal base.

Safe, quick and easy......