Battery Terminal corrosion

[kpgraci]

I have two batteries, the negatives are connected by a short 8 inch wire then a common negative goes to the house panel. The positives each go off to an A/B switch then to the house panel.
Both batteries are the same age, about a year. Last I went to the boat one of the negative terminals was heavily corroded, I could not even see the terminal lug, but the negative on the connected battery, 8 inches away, was clean. Does that indicate a problem with the corroded battery? Both test OK (in the green) with my simple panel test meter, and both seem to provide adequate current. I have seen corrosion on car batteries on occasion but never on my boat batteries, don't really know what it means.

 

[Davidasailor26]

What kind of batteries are they, Flooded, AGM, or gel? Also, are they in separate battery boxes or a common compartment?

 

[kpgraci]

What kind of batteries are they, Flooded, AGM, or gel? Also, are they in separate battery boxes or a common compartment?

AGM, 55Ah, in same compartment. Had this same setup for years, different batteries every 2-3 years, never had a problem.

 

[kpgraci]

Found this related to car batteries, should apply: "if the corrosion is occurring on the negative terminal, your system is probably undercharging." Not sure of the mechanism there, but OK.

 

[Justin_NSA]

I saw the same read. Could one be getting weak? Loose connection?

"Corrosion on the terminals is due to hydrogen gas being released from the acid in the battery. It mixes with other things in the atmosphere under the hood and produces the corrosion you see on the terminals. Generally, if the corrosion is occurring on the negative terminal, your system is probably undercharging. If on the positive side, it is probably overcharging. Most often it will be seen on the negative side because the battery is usually in an undercharged situation."

 

[SG]

Could be that the case is cracked? or the Terminal connection at the case is damaged?

AGM's should NOT be outgassing hydrogen -- certainly not at the terminal. (There are emergency vents. Those aren't right at the terminals. I would think that your battery case would probably show signs of bulging and/or distress.)

 

[justsomeguy]

Clean it up and give the post and clamp a good coating of silicone grease.
Then keep an eye on it.

 

[Maine Sail]

With an AGM this usually happens when the seal for the post is leaking. It can be caused by the heat from a high resistance connection or just a latent defect.. A leaking AGM can eventually “dry out” so keep an eye on it.

 

[capta]

With an AGM this usually happens when the seal for the post is leaking. It can be caused by the heat from a high resistance connection or just a latent defect.. A leaking AGM can eventually “dry out” so keep an eye on it.

Would you suggest something like 5200 or epoxy resin as a repair for this scenario?