Of battery terminals & grease

There are some members of electronic forums that suggest coating automotive battery posts with grease ("any king--axle, lithium, copper") before
attaching cable-end clamps to the posts and swear that it doesn't affect the connection adversely.
Are they nuts? Grease between terminal elements?
What grease--if any--is best, inside or outside the terminal connection?
Thanks.
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It's fine, because the posts are soft lead, and so is the terminal lug, and so they deform to fit one another squeezing all the grease out except in places of poor contact anyway.

Dielectric grease is good, but you can also purchase a strongly reducing "battery protectant" material in a spray can which is grease-based and works well. --scott
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On 24 Feb 2015 13:55:01 -0500 snipped-for-privacy@panix.com (Scott Dorsey) wrote:

I wish I had known about this spray will have to look for it next time.
the young men at the parts store said the only grease they knew about was in the tiny ketchup-pack size they were busy bragging about how they had ripped off customers "she didn't need a battery but I sold her a new one anyway, then sold her old one for $30" and so on.
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Not nuts... clamps :-)
The trick here is the fact that the clamps are tightened down well when you install the battery cables. The tightening pressure is sufficient to force the surface of the metal clamp into direct contact with the (soft) lead battery post, squeezing all of the grease out of this area.
You end up with just about the same amount of direct metal-to-metal contact between post and cable-clamp that you would if you hadn't used grease. The grease which remains, fills what would otherwise be air voids between the post and the clamp. The grease will block oxygen and moisture (including leaked battery electrolyte) from penetrating the connection and thus will help preserve the quality of the metal-to-metal connection.

http://www.w8ji.com/dielectric_grease_vs_conductive_grease.htm
"In single low-voltage terminals or connections, such as metal-to-metal joints, grounds, or battery posts, almost any pure grease of light viscosity will be acceptable. Caution should be used with greases containing metallic powders to be sure any metal is compatible with the embedded grease metal. Connection enhancement from embedded metal powder is very minor, if it exists at all, and there is increased risk of bad connections if the metal powder has any interaction with the base metals."
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On 02/24/2015 10:36 AM, Fester Bestertester wrote:

Grease can improve electrical connectivity if designed for that purpose - check out Dow Corning #4 dialectic grease - we use it on many power connectors and it not only reduces contact friction, and protects against oxidation, but the connector actually is often cooler than one without the grease added!
John :-#)#
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On Tuesday, February 24, 2015 at 1:59:03 PM UTC-6, John Robertson wrote:

Baking soda in a cup of warm water and use a rag to remove battery and cable corrosion and then rinse off battery and dry.Caution: Ddon't let it get into the battery cells.
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On Tue, 24 Feb 2015 13:54:09 -0800 (PST)

What causes the corrosion to build up in the first place
is it leaky battery or too much heat or bad battery or something else
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wrote:

Yes.
I wouldn't use non-conductive grease on a battery post because the connection will not always be as tight as it should be.
They sell small envelopes of dielectric grease at the parts counter of consumer autoparts stores, like Pep Boys, Autozone. The size of envelopes of ketchup and on a rack next to others with brake-pad-anti-squeak. spark-plug-anti-sieze, and a couple other things. It costs between 1 and 2 dollars. Enough for two cars, at least.
They have the envelopes at real autoparts stores too, but not right there on the counter.
Do some cars still come with spring loaded battery-cable ends.? They can't be tightened any more than the spring inside makes them tight, and they eventually get loose, regardless of grease. When they're not tight enough, they should be cut off and replaced with an add on cable-end, or if there's not enough slack, a whole new cable. Even on those with bolts for tightening, I've seen the bolt or nut or the lead that holds the bolt in place get stripped and require replacement.
If when the car is runnning or you're cranking the engine, the battery post and the clamp surrounding it are hot to the touch, the connection there is bad. A good connection will not be discernably hotter than "room temperature." Backwards from the way it might seem.
With a battery cable at the battery post, after it cools enough that you won't burn your hand, or with a leather work glove, you can very often have success by grabbing the cable and rotating it around the post 10 or 30 degrees, and then pushing it back where it was (and pushing down at the same time, so it might be on a little tighter) It's likely to be loose enough to do this, because if it weren't loose, you probably woudn't have the problem in the first place. Also buy a battery post/terminal brush. Two brushes in one piece, for 4 dollars in plastic, 6 in metal. You'll need to use this whether you use grease or not, before you put on the grease. . One brush should last you for the rest of your life.
I've never used such grease on battery posts, and I've never had a problem there. But some people might. With a '65 Pontiac, I had major connection problems between the positive battery cable and everything else at the starter motor. If I left the headlights on for two hours or more when the car wasn't running, the starter motor would barely turn, even if the battery was jumped. I don't think such grease was easily available in 1969. It certainly wasn't on display at the parts counter. Maybe it would have solved the problem.
After the new car dealer where my brother bought it replaced the starter, alternator, and regulator twice each, they said, and then woudlnt' try fix it anymore (even though they had never fixed it) because they said the two-year warranty had expired, my brother went to Viet Nam and gave me the car. and when I took it to Sears for one more battery, they found the problem for free in less than 5 minutes. What the dealer couldn't find in 2 years. The Sears man took apart the connection and scraped or cleaned the parts. When it happened again (after leaving the headlights on) at first I took it apart too and scraped the parts with a knife, but eventually I learned to reach under the car, grab the battery cable and pull it towards me once and push it back once. I could do this in nice clothes without even getting dirty, except my hand a little bit. Maybe you can't do this with a compact or small car. Eventually I came across a buzzer that buzzed when the lights were left on and that solved the problem .
When I got to my brother's city three years later, the dealer was out of business. Maybe because they didn't know how to fix a car.
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On Wednesday, February 25, 2015 at 11:35:43 AM UTC-7, micky wrote:

You don't recommend non-conductive grease but recommend dielectric grease? A dielectric is non-conductive, by definition.
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On 15-02-24 11:36 AM, Fester Bestertester wrote:

The only purpose of the grease is to keep the elements out of the connection. Clean terminals and clamps thoroughly. Use baking soda mixed in water if there is any encrustation and keep the resulting froth out of the battery cells. Dry with a paper towel then smear everything with Vaseline and reassemble. Tighten. wipe any excess forced out Vaseline off. It's worked for thousands of users for the last few eons. A few posters seem to think 'dielectric grease' means conducting...it doesn't.
In the electrical field there is an anti-oxidant grease called No-Alox or Penetrox. It's a greasy paste with what may be metallic particles in it. The only purpose of that is the same as above..it keeps moisture/oxygen out of the joint to prevent aluminium or copper oxides from forming. Those are non-conductors, as is the anti-oxidant paste itself.
mike
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I don't go anywhere near my batteries with baking soda. I don't let mountains of oxide build up, either. Put grease on after assembling connections. It is to keep air out. Flux brush and petroleum jelly. Whatever.
On 02/26/2015 12:52 PM, m II wrote:

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On Tuesday, February 24, 2015 at 11:37:02 AM UTC-7, Fester Bestertester wrote:

I cranked the engine and measured the same tiny voltage drop across a clean, tight terminal without grease and with grease applied before assembly. I know that it's OK to grease the parts before assembly because GE used to sell silent wall switches that glowed in the dark. They were silent because they used mercury, and when I once took one apart, I found a couple of cylinders about 1/2" - 1" in diameter and maybe half that thick that probably contained the mercury, and they rotated in holes filled with clear grease (silicone?). I reassembled the switch with those cylinders turned 180 degrees the wrong way, so the switch turned on when the lever was flipped down.
Use any grease that won't melt at high temperature and drip, especially into the battery. Axle grease is probably fine. I use Sta-Lube alumina-based disk brake grease (named so because it's for wheel bearings that ride inside disk brake rotors), simply because I have it and I'm not sure I can mix it with lithium-based grease, which is a lot more common. I learned as a yout that you shouldn't mix lithium-based and sodium-based grease because that forms a grit that wears out ball joints fast.
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