BFL13 wrote:
My battery book says charging is also an oxidation process that corrodes the positive plates with prolonged overcharging (as when the float voltage is a bit too high I guess).
The positive post is to the first positive plate in series in the battery, so would it get corroded more than the others and would that make for more gassing from its cell than from the others?
Doubt it, otherwise every single DC connection would have the very same issue.
Terminal corrosion typically comes from battery acid, this can come from excessive over charging resulting in excessive gassing and the battery must vent that. The venting vapor will have residual acid in the water droplets that are vented (the reason the Gel or AGM batteries do not have this issue, when those batteries have to outgas you have done something badly wrong).
Poor or bad seal on the terminal to battery case can also cause corrosion, typically the POSITIVE terminal in most automotive applications. On older vehicles the positive wire was extremely short since it went to the solenoid mounted beside the battery. This didn't give enough slack for movement and vibration.. Eventually over time the terminal to battery seal would fail and acid would creep up the terminal (wick). The negative terminal seal typically did not fail because that wire ran to engine and frame and had lots of slack.
I have experience this issue with older vehicles and even a tractor, new vehicles since the 1990's I have never had a terminal corrosion issue.. Coincidence? I don't think so, more modern vehicles MOVED the starting solenoid to on top of the starter.
Since terminal corrosion and all that hard work it is to take care of FLA batteries subject comes up often I decided to take a few photos of my GC2 batteries while I was checking the water this fall..
Ignore the water on the top, pix were taken AFTER I added the water.
For the record, those are Extra flex 1/0 cables so they are far less stiff (1000+ little tiny strands of fine wire)than what is in a automobile or even on your RV connections.
Those batteries were installed in 2017 and the terminals are so clean you could eat off them.
I did use a small dab of "OxGuard" per connection which is same as "No-Alox" which is used for electrical terminations with aluminum wire to electrical panel terminations. I have also found OxGuard works great for any electrical termination that may be exposed to high humidity or outdoors..
On edit, I should also note that this trailer sits only 10ft off a busy road, it is below the road level and road is heavily salted in the winter (salt spray is so bad that I have to take anything made of steel on my home front porch in for the winter) so some of the steel bolts have some rust and the homemade terminals I used are soft copper pipe with two layers soldered together for good measure.. The solder is showing some weathering and copper is not as shiny, but hey, it has been 12+ yrs with that setup..
