the black box on the ground terminal

[sixleggedinsect]

a while back i asked for folks who knew what the black plastic box on the ground terminal of the battery was. recently, ive been playing with it- here is a description, copied from another of my posts.

-begin copy-

a while back, i had had some recurrent corrosion problems and despite repeated cleanings and attempted greasings, etc, it kept coming back. the wires were pretty corroded, and i wanted to rip out the entire box and splice in new pretty wire. i dropped by a dealer in utah whose mechanic was on break (ok, so im cheap) and asked him what the box was. he said it was a charge controller and that if i removed it the car would not work, but that it woudl be fine if i cleaned it.

so i cleaned it and three weeks later started having these problems. it turns out the small wires entering the box were very corroded, far more so than the exterior main ground, and i hadnt been able to see these.

the dealer mech im actually paying says to rip it out and splice in new stuff. he assures me it is just a junction box, which is waht i originally suspected.

so i ripped it out, wired in a new terminal, spliced in new wires (four or five sensors or other wires ground here) and bolted on the main ground. it worked fine, and the check engine light has not resurfaced since.

i also replaced the battery, as i suspected that my repeat corrosion problems, as mentioned elsewhere, were due to a battery that was spewing acid all over the place. this was reinforced by a acid-sensing battery cleaned spray i picked up for a couple bucks. every drive would find more acid on top of the battery.

but the jury is still out- i did have some very weird starting problems soon after i replaced the ground hardware. i was using a lead terminal and everything else bolted on. the battery and terminal were wirebrushed clean, and silicone dilectric grease put between the faces, and the external parts were spray painted. three or four times within two days of the new parts i would go to turn the car on, and it would (for a fraction of a second) start (with the engine turning, fuel pump running, etc) and then would die completely. completely dead. like the car coughed and died. no power whatsoever after that. no lights. no radio. no warning lights. the only thing that woudl bring it back is if i took the terminal off, looked at it with a grumpy face, and put it back on. sometimes i had to do this several times. multimeter readings would read weird stuff. ground/pos voltage: 12.6. lead battery terminal/pos voltage: one or two volts. repeatedly. it did not rationally or regularly respond to tightening, wiggling, cleaning, re-cleaning, etc. totally weird. the lead terminal was somehow not making a good connection. sometimes it took me fifteen minutes of taking things apart and being grumpy and putting them back together before the car woudl work again. at least once the ground terminal smoked (arcing?) when it 'coughed' and died.

finally, i switched the lead terminal for a cheaper stamped steel one and it has not had problems since, althouhg it has only driven around 10 hours since the second terminal change-out.

i have the black box, and if i have no problems within the next month, i will cut it open and see if it is just a junction box for sure.

[sixleggedinsect]

after a year of driving around without that box, i never had any problems with it. it was so corroded and junky i ended up tossing it without taking it apart, but im convinced that its either a junctio box to save a robot/mechanic time in the factory, or it isnt necessary.

[denisond3]

I replaced mine (the black goody at the ground terminal) by stripping all of those wires back, wrapping them around my new ground cable (with a real lead terminal) and putting a large glob of solder over it. Besides the corrosion, it also fixed the problem I had of the water temp gauge reading too high all the time.
Each time I take the terminals off a car battery, I clean the inner surfaces of the terminals and the outer surface of the battery posts, using the blade of a pen-knife and a scraping action.
I like the name 'charge controller'. I wonder if the guy thought it really was such an item (which I've never heard of), or if he was teasing?

[AzTumbleweed]

Selectron, you have good schematics. What's it show?

[Intuit]

Regarding the leaky battery acid issue, I also noticed that my battery tray and beneath it were getting pretty rusted-out. Certain national or regional food chains like Popeyes have (or had) large, thick plastic bags that are temperature resistant; designed not to melt when carrying the hot foods that they serve. Several years ago I took one of these bags, dumped a bunch of baking soda in the bottom and put my battery in it, then reinstalled it. Put a little BS ontop of the batt as well. This effectively neutralizes the problem. Same bag is being used with the second battery now for about two years. Do *NOT* seal the bag at the top because the battery *NEEDS* to breath. But the deminished airflow will help keep uncovered battery terminals from corroding as fast. You'll of course have to neutralize the residual acid in and around the tray because it will continue to eat away at metals, but regardless this effectively nullifies the reoccuring issue.

I've dealt with the poor connection issue as well. Part of the problem is the battery posts on any of the ones I've had, are too small in diameter for the wire terminals. (not sure how this came to be) Another part of the problem is there just wasn't enough surface area of the wire terminals in contact with the battery posts. Regardless of the battery being good it would occassionally behave as if the battery were going bad or were dead.

After cleaning the posts and attempting to clean and "correct" the shape of the wire terminals I did a few critical things. 1) Used a metal spacer to get a tighter fit. 2) covered the battery posts in aluminum foil (optional + AL degrades/thins but seems to keep from having to reclean posts) 3) Used hammer and blunt object to firmly entrench the base of the wire terminal against the very bottom-base of the post, twisting it back and forth a bit once on there (for lots of suface-area contact) 4) replaced nuts and bolts with stainless versions and used cylindrical washers to apply more clamping force without stripping nuts/bolts (would've happened with the originals)

As an additional idea for suggestion it might even be possible to solder a highly-conductive, (not really aluminum) but slowly or non-corroding material to the inside of the wire terminals. (which is similar to the permanent solution for the door-jam switch problem as well) Certain blends of solder are highly-conductive but do not corrode easily. But they do have low melting points which in theory could risk bonding the terminal to the battery post (yikes) if amperage draw causes hot spots on a poor connection.

Emphasis or priority should be on the ground. You ground connection should always be better than positive.