Battery terminal corrosion

[RJJ]

Attached photo is one of 3x 150Ah AGM batteries which I dealt with late last summer but has not coped well with the winter.

So the other two I have scrubbed the terminals and reassembled with vaseline on the outside and will keep a better eye out in future. This is the worst of the three. I have removed the nut, but the retaining bolt for the connector is firmly gripped. I have added a tiny bit of GT85 and tried half an hour later but it won't budge.

With an adjustable, it's just possible to rotate the entire connector but I am not happy putting that much force into the battery terminal. And it doesn't help anyway with the principal problem, as I still can't take the connector off and take it to bits.

Any ideas welcome. What would eat the corrosion? Is it safe to apply a heat gun? What should I do to stop this recurring? If I get it undone, do I need to replace the corroded terminal which is very pink?
Many thanks indeed.

 

[PaulRainbow]

Attached photo is one of 3x 150Ah AGM batteries which I dealt with late last summer but has not coped well with the winter.

What do you mean ?

So the other two I have scrubbed the terminals and reassembled with vaseline on the outside and will keep a better eye out in future. This is the worst of the three. I have removed the nut, but the retaining bolt for the connector is firmly gripped. I have added a tiny bit of GT85 and tried half an hour later but it won't budge.

With an adjustable, it's just possible to rotate the entire connector but I am not happy putting that much force into the battery terminal. And it doesn't help anyway with the principal problem, as I still can't take the connector off and take it to bits.

Any ideas welcome. What would eat the corrosion? Is it safe to apply a heat gun? What should I do to stop this recurring? If I get it undone, do I need to replace the corroded terminal which is very pink?
Many thanks indeed.

Try tipping boiling water on it.

Wouldn't use heat.

If it's still stubborn, cut it off, it's scrap anyway. If you have other terminals that are corroded, get them changed, they cost peanuts.

 

[VicS]

Perhaps you have a slight acid leak around the post or salt water has been dripping on it.

You appear to have taken the nut off the clamp bolt. Can you not now pry the sides apart sufficiently to get the clamp off the post?. If not just cut it off.

I'm not so sure Vaseline is the best "protection " to apply. What do others use , if anything?

 

[PaulRainbow]

Perhaps you have a slight acid leak around the post or salt water has been dripping on it.

You appear to have taken the nut off the clamp bolt. Can you not now pry the sides apart sufficiently to get the clamp off the post?. If not just cut it off.

I'm not so sure Vaseline is the best "protection " to apply. What do others use , if anything?

I don't use anything, there's no need.

 

[Boathook]

Normally vaseline or sometimes contralube. Another option is ms4 silicone grease but I have never had corrosion that bad. Apart from contralube the others are used after making the parts together.

 

[RJJ]

What do you mean ?



Try tipping boiling water on it.

Wouldn't use heat.

If it's still stubborn, cut it off, it's scrap anyway. If you have other terminals that are corroded, get them changed, they cost peanuts.

Thanks, other terminals were a bit corroded but came off easily enough and scrubbed up ok. Little bit pink but seem serviceable - but point taken, I could replace for small £.

This one - I have managed to pry it off and now giving it the same treatment.

You say you don't use any anti-corrosion.... what's the solution? Just inspect and clean more often? These were clean last September and I am guessing they were damp over winter while connected to solar panels.

Thanks, much appreciated.

 

[pvb]

You say you don't use any anti-corrosion.... what's the solution? Just inspect and clean more often? These were clean last September and I am guessing they were damp over winter while connected to solar panels.

Battery terminals in cars are generally not greased in any way, and they don't have problems. I've never greased battery terminals on a boat.

 

[RJJ]

Update: so I managed to remove the terminal and will replace. I can manage on two batteries for a few days.

Here's the battery terminal which doesn't look great. The top bit was able to rotate in the connector; it doesn't look like the other battery terminals. Is this "terminal"? Or can it be fixed? It has 12.8v at the moment, same as the others having been running the fridge for a few hours since last charge.

 

[tillergirl]

I had the same at the end of the season. When I investigated I found that the battery post had some minor but nonetheless visible movement. So I reckon there was a little vapour from the battery around the post. I thought the battery might be dying but it has stood up well. I am keeping an eye on it. Although I do not normally use any thing I have for once put a smear of grease on the post. Best I check in the morning.

 

[RJJ]

Update: so I managed to remove the terminal and will replace. I can manage on two batteries for a few days.

Here's the battery terminal which doesn't look great. The top bit was able to rotate in the connector; it doesn't look like the other battery terminals. Is this "terminal"? Or can it be fixed? It has 12.8v at the moment, same as the others having been running the fridge for a few hours since last charge.

 

[RJJ]

I had the same at the end of the season. When I investigated I found that the battery post had some minor but nonetheless visible movement. So I reckon there was a little vapour from the battery around the post. I thought the battery might be dying but it has stood up well. I am keeping an eye on it. Although I do not normally use any thing I have for once put a smear of grease on the post. Best I check in the morning.

Thanks - if there was vapour coming out of a sealed battery, that implies it's drying out, right? And not just dying but dangerous...?

 

[PaulRainbow]

Update: so I managed to remove the terminal and will replace. I can manage on two batteries for a few days.

Here's the battery terminal which doesn't look great. The top bit was able to rotate in the connector; it doesn't look like the other battery terminals. Is this "terminal"? Or can it be fixed? It has 12.8v at the moment, same as the others having been running the fridge for a few hours since last charge.

No picture, but at just over £2 for a new one, why bother ? If you mean the stud rotates, it's threaded into the terminal body. But seriously, for the sake of £15 or so, why not treat the batteries to some nice new terminals ?

 

[PaulRainbow]

That explains the corrosion, probably not an easy fix.

 

[Plum]

Attached photo is one of 3x 150Ah AGM batteries which I dealt with late last summer but has not coped well with the winter.

So the other two I have scrubbed the terminals and reassembled with vaseline on the outside and will keep a better eye out in future. This is the worst of the three. I have removed the nut, but the retaining bolt for the connector is firmly gripped. I have added a tiny bit of GT85 and tried half an hour later but it won't budge.

With an adjustable, it's just possible to rotate the entire connector but I am not happy putting that much force into the battery terminal. And it doesn't help anyway with the principal problem, as I still can't take the connector off and take it to bits.

Any ideas welcome. What would eat the corrosion? Is it safe to apply a heat gun? What should I do to stop this recurring? If I get it undone, do I need to replace the corroded terminal which is very pink?
Many thanks indeed.

I have never applied grease or vaseline to battery terminals. A light spray with wd40 once a year and they stay perfectly clean and no corrosion of the bolts. I always get 8 to 10 years out of my batteries.

www.solocoastalsailing.co.uk

 

[RJJ]

That explains the corrosion, probably not an easy fix.

Thanks Paul - so you're referring to the battery post itself, right? Do I need a new battery? Or can the battery post be fixed?

 

[PaulRainbow]

Thanks Paul - so you're referring to the battery post itself, right? Do I need a new battery? Or can the battery post be fixed?

Just to be 100% clear, you're saying that the lead battery post, shown in your picture, can be turned on the battery ?

If that's the case, you'll need to fix it somehow or replace the battery, it will not be making a proper connection. It might be possible to drill and tap the post. You would need to carefully drill down the centre of the post, deeper than the visible part post, with a 6.7mm drill bit, then carefully measure the height of the post and drill down to that depth with an 8mm bit. Finally, tap the bottom of the hole that you drilled.

Alternatively, it should be possible to clean the post up, widen the crack at the bottom of the post to a vee shape and solder the break. This would need a big soldering iron and someone who knows how to solder properly.

 

[RJJ]

Just to be 100% clear, you're saying that the lead battery post, shown in your picture, can be turned on the battery ?

If that's the case, you'll need to fix it somehow or replace the battery, it will not be making a proper connection. It might be possible to drill and tap the post. You would need to carefully drill down the centre of the post, deeper than the visible part post, with a 6.7mm drill bit, then carefully measure the height of the post and drill down to that depth with an 8mm bit. Finally, tap the bottom of the hole that you drilled.

Alternatively, it should be possible to clean the post up, widen the crack at the bottom of the post to a vee shape and solder the break. This would need a big soldering iron and someone who knows how to solder properly.

Ok many thanks indeed, makes sense