Question : what is the proper way to clean battery terminals and leads that aren't making a good connection?
Last week, after charging my battery when it was flat, I noticed a lot of that bluish-white salt stuff built up in the negative battery lead. I cleaned it off and reattached the lead, and then as I was doing up the nut with the spanner, I got a massive spark discharge and burning bits of stuff flew off. I take this to mean that the lead is not making a good connection to the terminal, and the spanner caused a connection when it must have come into contact with the terminal properly.
Hmmm I bet you were putting the positive terminal back on, and your wrench touched something grounded. You could have had a battery explosion... glad your ok. Look at your wrench; on the end opposite to the end you were using, you'll probably find a burn mark. Another burn mark will be on the car where the wrench touched.
You really should always take the negative cable off first when disconnecting a battery. When reconnecting, the negative goes on last. That way if your wrench touches something with ground potential, your safe. (However, if you wrench should simultaneously touch both battery terminals/posts you'll still get the big arc. Even though possible this is a little more difficult to do by accident as most wrenches aren't that long.)
Google a little, you'll find a good bit about this. There is also a 'safe' order to connect and disconnect jumper cables... again Google away.
Auto parts stores have special battery terminal brushes... they're cheap and work great. You can also submerge the cable end/s in a mixture of baking soda water and the corrosion salts will boil away. The baking soda method doesn't work well if the terminals are oily or greasy. Keep the baking soda mixture out of the battery.
Once you get the terminals clean and installed, giving then a good coating of heavy grease will prevent further corrosion. Be sure to pack it in well under the terminal. (Acids don't attack grease)
No - I attached the positive lead first and did its nut up and put the protective cover on; and then attached the negative lead, and then as I was doing up the nut on the negative lead, the spark happened. I was standing clear of the car and the spanner didn't touch anything apart from the negative stuff.
I just use wheel bearing grease... I have an old tub that became contaminated, and was delegated to battery use years ago, I think it might be sodium base if I recall correctly. I don't think I would use Moly-disulfide or the like. Others here might have more info.
Strange you got such a big spark... were the lights or something on?
to get that spark either something is turned on or you have a short somewhere. I guess the clock runs all the time so a very small spark might be normal.
I think the reason your battery was flat involves that big spark you saw. That indicates a large draw on the battery. There should only be a small crackle when the post tightens up, not a chunk blowing arc.
I use dielectric grease over my terminals to help keep corrosion down.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 'New' frame in the works for '08. Some Canadian Bush Trip and Build Photos:
why was your battery flat? maybe your alternator is short. I am not sure what the best way of tracking down a short would be. the short is probably not in an area protected by fuses or a fuse would have blown.
I recharged the battery and tested with an ammeter before connecting the negative lead, and it showed 600mA being drawn. I believe this is quite high (my other car of the same manufacturer and similar year only draws 200mA). I might have to take it to an electrician to get it checked out.
(I googled and it suggested doing voltage drop testing on the alternator, but my alternator is in an awkward place).
Right, so you apply that to the terminals before connecting them?
600 milliamperes is far too high for quiescent residual current. Now, when you first connect the battery, some systems may temporarily draw increased levels of current but they should quickly settle down. Normally you should not draw more than 30-40 ma, or a little higher, at steady state with everything turned off.
The 600 ma level is not acceptable if it stays that way.
You can slather the terminals with dielectric grease before you connect them. You can give them a heavy coating after you connect them, but you will not get the same level of protection.
Because it is dielectric grease, it is non conductive so I clean the lead nice and clamp it tight before adding the grease coating.
I live in the salt/rust belt and even with grease the older batteries and cable need a clean every 2-3 years or they will give trouble.
Sometimes you can narrow down a draw by pulling fuses. You pull one at a time looking for the drop, then you have the circuit in question narrowed down at least.
I don't mind slathering on dielectric (non conductive) grease to push on connectors because they scratch a connection, but think lead on lead is the best for battery posts.
Just my $0.02,
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 'New' frame in the works for '08. Some Canadian Bush Trip and Build Photos:
Ive done it both ways...Dielectric greases do not conduct, but with a tight terminal there is plenty of lead to lead contact. The lead oxides and other lead compounds which form due to corrosion can be deep and nonconductive, and that is what I want to suppress.
I believe I get better protection when I add it to the total terminal, but would not argue the concept.
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