Hi folks,
Here's the situation: I have an auxiliary battery in my 4wd that's been in for about 2 years (installed + bought the battery at the same time, all new). All good, no problems to date, except a bit of corrosion building up at a fast rate on the positive terminal on the battery.
On the trip out this weekend, the fridge was running fine while the engine was running, but as soon as it was off would only last about 2 minutes before turning off and throwing the error code for voltage drop.
So poked around under the hood, found the positive battery terminal for the auxiliary just caked with corrosion; layered in between the ring connectors, battery, and clamp, and a full mm think and stuck on hard to the whole outside.
So I scrapped off what I could in the field (a poor job), and reconnected, fridge lasted 20 minutes after that. (Then died, but the truck had only been running 5 minutes to test after cleaning the terminal a bit so I'm assuming it was not charged properly as a result of the poor connection. Also the water was low, which I topped up when I got home. But haven't had driving time yet to charge and test again.)
In all this though, I noticed that the ring terminals the installers have used for the positive terminal on the auxiliary battery are copper. At the rate the corrosion builds I would have to be scrubbing it once a fortnight to keep clean which obviously isn't right.
The negative on the auxiliary is nickel/steel (I think? whatever they normal stuff is), and both on the starter battery are the same. These are all perfectly clean, and the starter battery terminals have hardly been cleaned in 10 years, so can rule out an environmental cause.
Is the copper terminal causing galvanic corrosion?
Should I be switching the connector rings to something not copper?
Seems like the obvious cause as it's the only difference, but I'm no electrician.
Cheers