battery corrosion

Robski97

Robski97

Well-Known Member
Jan 15, 2007
1,828
North Bellmore, NY
Boat Info
44DA
Engines
Cummins QSC 8.3's
Anyone have a clue why one battery on each bank would have massive amounts of corrosion on only one terminal. After i cleaned off the gunk. I checked the terminal and it was tight. im clueless . The batteries are only a year old....

Thanx


Rob
 
Id have to say yes... boats only year old..

But if thats the only thought .. ill pull the terminals....

There was no corrosion when i put her to sleep in december....

It all happend over the winter while not plugged in .....

Rob
 
Some grease should help prevent the corrosion.

Alex.
 
If you use grease make sure it is dielectric grease so it does not insulate the connection.
 
Rob:

A few Q's....when it was winterized, I assume the batteries were left on board. However, were ALL terminals left connected, or only some...and if some, are the some the ones that are corroded???


Is the corroded terminal a Neg or Pos terminal???

I agree with the above that tight, clean, greased terminals, with a "terminal pads" under the cable connector to help isolation with eliminate future corrosion.



later,
 
Dom,
They were all connected and were not charged over the winter....( 6 batteries total )

I want to say it was the neg terminal on both batteries.. Im not 100 %

I did some google search's for batter corrosion and i read enough to make my head explode... but one scenario is a bad battery... A leaking post ... if the term's are clean and tight ... battery is new... it states batter could be bad... how about them apples....

So i have to look ... how does one check for gassing at the terminal...

so we will see...


thanx guys

Rob
 
Rob, you don't say how your batteries are connected, or what type they are. Do you have a 12v system or a 24v system?

Are the batteries wet cell where you can add water, or are they "maintenance free"?

Do you know what the overall battery voltage was at the end of the season when you checked?

Was there any electrical load at all on the batteries, such as a CO detector?

If you have a 24 volt system, and you have any load that can cause the batteries to discharge, then it might be possible for a cell to 'invert', or change polarity as the battery discharges. This is almost impossible in a 12 volt system, and can easily happen in a 48 volt system. An inverted cell can probably be corrected by charging, but it will likely not be up to par anymore.

If you have normal wet cells, then the cells will gas when you charge them. The rate should be the same for all cells, and should go out the vent caps. This is the reason you have to add water. So there really would be no need to check for gas venting in this situation. If you have a bad seal around a post, then it can vent there too, and it puts the corrosive gasses that much closer to the metal parts that corrode. But this in itself does not constitute a useless battery, it just requires more work to keep the battery terminal clean.

It is very common to see one post have more corrosion on a battery than the other. I think it is the positive post, but don't remember for sure.

If you have sealed batteries, and you have a leaky seal around a battery post, then you will likely lose water from that cell quicker, and will have no way to replace it. Thus a replacement will be required when it no longer functions.

Battery posts are often made of copper, and coated with a thick layer of lead. The copper will corrode in the presense of the acid gas, but the lead will not. So if gas leaks by the terminal post, it will try to find copper to react with and form the blue-green corrosion you see. Nicks through the lead on the post that expose the copper can let this happen. A good coating of no-ox over the post will help.

Then look at the cables that attach to the post. They should also be lead coated, but will often be copper. If copper, and the post seal leaks, then you are guaranteed to have corrosion unless you have things greased up, and do it at least every six months. So look for wire terminals that are not lead coated. They may be the culprit.

All that said, you should not have much gassing over the winter when not plugged in. It is the charging that causes gassing. But if you have a weak cell in a string, and there is some load, then the stronger cells will supply current through the battery and weak cell, further discharging the weak cell. In a 48 volt system it would cause it polarity to switch. But in a 12v system, each cell is much more of the total, and this is not so likely to happen.

On a long term, many year scale, most batteries will suffer from positive plate growth. The positive plate gets physically larger, and pushes against the seal, often breaking it. But this should not be your problem with a year old battery set.

If I were you, I would remove all cables, and wash the ends in a water with baking soda added to neutralize any acid. Then clean off the battery top and terminals with water, and maybe a bit of baking soda. Don't let the baking soda get into the cells. Get some no-ox or equivalent at an electrical supply outlet and coat the posts. Coat the cable ends, especially where any bare copper shows. Then bolt it all back together. Make sure the cells have adequate water if possible. Then put the batteries in service and monitor your batteries individually with a voltmeter to make sure you don't have one or two that drop in voltage much quicker than the others.

The corrosion you see around battery terminals, especially if blue-green, is copper sulfate. It can only form if the sulfuric acid gas can get to copper. I would not blame this type of problem on a connection that was not tight enough. The more you tighten it, the more likely you are to penetrate the lead covering on the wire terminal end or the battery post.

This thread belongs in the electrical section.
 
Dave,
Thank you.... ITs a 12 volt system with maintenance free wet batteries. Just found it odd only 2 of the 6 were affected.

Im thinking its a bad seal around the post...


Ill try ur suggestions ...

Thank you


Rob
 
I took some pics. It looks like the posts are leaking on 4 batteries.
Also the caps on a few are leaking... What the heck.. Im waiting for an answer from the dealer.. but i want all the batteries changed... if 3 did it odds are the other 3 will
 

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Just a thought on the "corrosion" topic. For corrosion protection, you might want to consider "CORROSION X" (MARINE), by Corrosion Technologies, to battery terminals and anything else you want to protect from corrosion. Whatever corrosion protection is used, it must be applied regularly. This stuff is wonderful. I used the aviation version (blue can) for years on many components in my airplane, including battery terminals. Never, ever, had any rust or corrosion. So far, no corrosion on our 410 Dancer (2000) on components in engine compartment, including the battery terminals. A shot on the terminals once a month and you will never have a problem. :smt038

GOOD LUCK!!

COURT SHIP
 
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