Broken battery terminal, repairable?

[Ricco1]

I've noticed that the positive terminal on one of my leisure batteries has sheared off. It's a bolt type terminal rather than the round post type. So this battery is now effectively redundant.

 

The obvious thing to do is replace the battery. The problem is that the battery box would need dismantling/ destroying as it's held together with rusty screws with rounded Phillips heads. This got me round to thinking whether I could perform a repair along the following lines:

 

Obviously a soldered joint isn't that strong, probably too weak to simply solder the post where it sheared off. How about: about a short length of suitable wire and crimp a ring terminal to it, this ring terminal then attached to the other wires with the remaining bolt. Another ring terminal on the other end of the short piece of wire, this is then soldered to what remains of the terminal post. If I got the length of this piece of wire right there should be little pressure on the soldered joint.

 

I wouldn't attempt this if it were a BSS fail.

 

Any thoughts?

[bottle]

Replace the battery.

[RLWP]

Replace the battery.

 

What he said

 

Richard

[The Bagdad Boatman (waits)]

The old method is to melt lead and pour it into a mold on top of the broken terminal, you can use a round post clamp as the mold. Beware that the battery must not be venting explosive gas by charging or discarging. Annother way is to use a pan head self tapper screwed into the remains of the clamp and solder a ring clamp on. How old is the battery and how good.

Edited July 2, 2015 by The Bagdad Boatman (waits)

[Burgiesburnin]

The old method is to melt lead and pour it into a mold on top of the broken terminal, you can use a round post clamp as the mold. Beware that the battery must not be venting explosive gas by charging or discarging. Annother way is to use a pan head self tapper screwed into the remains of the clamp and solder a ring clamp on. How old is the battery and how good.

We used to use the self tapper fix that you mention. It mostly worked well

[cuthound]

Battery posts, group bars and plates are held together by pouring molten lead into a former holding the component parts together and letting the lead solidify.

 

This is a very rare skill nowadays. I haven't seen it done since about 1975. Even if you could find someone with the relevant skills it is likely he would charge more than anew battery.

 

Using a self tapper to fix will only result in corrosion and eventually another failed terminal post. May be OK as a quick and temporary fix.

[Neil Smith]

Could you drill through the centre of the sheared post then tap a thread and screw in a bolt.

 

Neil

[Tony Brooks]

Ah - I used to build and repair batteries so can/could fit a new post if I had the mould, small gas-oxygen or at a pinch welding torch and led strip.

 

It is not as straight forward as earlier posts have suggested because one needs to melt the top of the remaining lead to get a good bond with the new lead. I used a brush hook "puddle the old lead and also to get heat into it. The gas flame tends to self extinguish in the bottom of the mould. You also need to keep puddling as you melt the leads trip into the mould to ensure the lead doe not set in discs.

 

If you over do the puddling and get the job too hot the molten lead tends to melt the plastic cell lid and run out of the bottom of the mould.

 

Last time I did in was in the 1980s for MOD training vehicles (apprentices kept snapping the posts off). Before I did that job someone tried to use the carbon from the centre of a dry cell connected to the other post as an arc heater but it was not a success.

 

I would also say self tapper or new battery.

[David Mack]

The self tapper might be OK on a leisure battery, but surely wouldn't cope with the current of a starter battery.

[Tony Brooks]

The self tapper might be OK on a leisure battery, but surely wouldn't cope with the current of a starter battery.

 

Depends on size of screw, how flat the top of the remaining lead is, size of terminal and contact area. Agreed its far from ideal but always worth a try. It might save dumping a serviceable battery.

[RLWP]

Depends on size of screw, how flat the top of the remaining lead is, size of terminal and contact area. Agreed its far from ideal but always worth a try. It might save dumping a serviceable battery.

Is it worth it on a day hire boat though. Getting called out to sort a boat with a dead battery and unhappy hirers doesn't seem worth the risk for the cost of a battery

 

Richard

[Tony Brooks]

Definitely not, especially as the cost of the new battery is tax deductible.

[Ricco1]

Stupid me, so focussed on the broken terminal that I failed to spot that this particular battery also has a round post. My excuse, it's at the back of the bunch, so difficult to see anything. Poor excuse, I know.

 

So the solution is simple: get a suitable round post connector, get a slightly longer link wire so it fits, sorted. However: the voltage on the disconnected battery is showing at 10.8. It's possible it could have been disconnected for months. Is the battery likely to be shot, showing such a low voltage?

[Tony Brooks]

Probably well sulphated so will have reduced capacity but untill you starts charging it and look for individual cell gassing more than the others you will not know if it has an internal short.

[Ricco1]

So I guess the thing to do is spend a couple of quid on a connector and new lead, then monitor the performance once it's properly charged?

[Tony Brooks]

Yes.