Help why is my battery terminal corroded and sparking?

FWIW, there is zero need to goober up dielectric grease all over the battery terminals and lugs.
If the batteries aren’t leaking and the connections are clean,they will very reasonably stay that way.

theoldwizard1 wrote:

rvshrinker wrote:
Last looked at these batteries one month ago. Today before our trip there is a small amount of blue green corroding at the terminal, and along 3 red wires connecting to it at their terminals.

Corrosion forming around lead acid battery terminals is from a small amount of gas that is leaking around the terminals. It is impossible to prevent this leakage as a battery ages. You can buy those pricey battery post "donuts" or just gob a large amount of Vaseline on the post and terminal/clamp. Remove the terminal so that the Vaseline get under the terminal/clamp right up close the the seam between the post and the case.

BEFORE YOU DO THIS, clean the terminals, cable ends and the ENTIRE BATTERY OUTSIDE CASE with baking soda and water. Rinse well with clear water.

rvshrinker wrote:
Also there is a small amount of sparking when the red wire is brought to the terminal. Never seen this before. What's going on?

If it is small, ignore it. It just means that something is turned on when you connect it.

Not much else to be said. I used Vaseline for years, more recently I use Dow 4 dielectric silicone grease, but same thing, pull clamps, clean everything throughly, slather it with grease, reinstall clamps and tighten, slather them with grease, working it into the gaps in the clamp around the bolt if a car terminal type, but coat everything throughly.

Charles

If you have an inverter it may be the cause of sparking when reconnecting batt wire. Mine did this for years even though inverter was shut off. I proved it to myself by disconnecting inverter 12v wire and had no more sparking. I concluded there must be a capacitor in the inverter that discharges when batteries are disconnected, then draws some juice again as soon as batt wires are connected again.

A small spark when conecting battery cables is normal. You can buy battery carosion remover and preventer at autozone. Works very good.

Typ shrinker lack of response or return to thread.

If you have a multimeter set it to 10 amps and check the amp draw. If you see several amps something is left on. If less than 1 amp it is it is normal parasitic draw. My is about .4amps and will spark when I connect my neg cable to post. Don't overfill cells with water, clean connections every so often, and clean the top of your batteries also to minimize self discharge.

Unless you have a battery disconnect switch that is turned off or have the battery fuse in the converter removed, you almost always have a circuit wanting power. On my TT, things that are always drawing power are the CO detector and the radio (even when turned off) When you attach the battery cable, there will be a spark as the circuit is completed for these items.

Getting a spark when hooking up to a battery terminal means there is a draw on the system that is waiting for power. You need to know what is operating directly from the battery.

rvshrinker wrote:
I have to unhook my connections every time we get home and take off because I have an electric dolly to move my trailer into its carport, and the dolly requires the trailer batteries for power.


The batteries are original 3 yo 6v deep cycle. The trailer stays plugged in at all times we are not camping. I never use the tiny solar panel and it's under a carport anyway.

^ That sounds like a pain in the ___, unless it's only couple times a year. Wire up a simple winch plug or similar and plug the dolly in when needed.
But you didn't address the most important question. Are you slow cooking your batteries or not?

It's possible the connection was not very tight. I cleaned everything up and tightened it and there was a tiny spark, which as some have mentioned might be normal. Obviously it's right next to my propane so I don't want to take any chances. I have to unhook my connections every time we get home and take off because I have an electric dolly to move my trailer into its carport, and the dolly requires the trailer batteries for power.

I will add some vaseline as well.

The batteries are original 3 yo 6v deep cycle. The trailer stays plugged in at all times we are not camping. I never use the tiny solar panel and it's under a carport anyway.