Do you guys grease the battery terminals upon connection as advised in the X300 handbook? (It says vaseline, but I'd use silicone grease if anything as it's less migratory)

I've seen many a debate about this. Some folks are convinced it's a bad idea to have a non-conductive grease like vaseline on the contacts, but the way I see it, the grease will be displaced as needed when the connector is pushed on and tightened, and there will be the same amount of metal-to-metal contact as there would have been otherwise, the only difference being that the gaps will be filled with grease instead of air.

The X300 handbook recommends grease, but it's worded strangely "coat post bases with petroleum jelly" - why does it say post "bases"? Not the whole post?

The X300's battery doesn't live in as hostile an environment as most car batteries do, so I don't suppose this question is of vital importance, but I'm curious as to your thoughts on greased battery posts.

 

The idea is to replicate those donut looking felt rings that are saturated with I don't know what. With the battery leads bolted securely to the posts, the corrosion will not occur with a good contact. The corrosion occurs between the battery top (where gunk accumulates) and the lead bottom. Those felt Washer things alleviate that. So will some sort of grease, as you stated. I'd assure that NO grease gets on the posts themselves.

 

There really shouldn't be any debate.

If two surfaces are meant to conduct electricity, it is a bad idea to put
a non-conductive barrier between them. That includes dielectric grease,
which despite the "electric" part of the name is a conductive barrier due
to the "di" part of the name.

The Jaguar instructions are directed at applying the vaseline after the
post and clamp are fastened.

If someone wants to use grease on the posts, then a conductive
grease as sold to electricians to prevent corrosion between conductors
is a better alternative. About $4 a tube.

 

That makes sense - to seal the the seam between metal posts and the plastic hole they come through, right?

The exact sequence in the handbook is:

Which doesn't support the idea of applying the grease after the clamps are on.


I think I understand what Jaguar had in mind now and I wont grease the posts, but I'm not convinced that doing so would be a particularly terrible idea. If you've ever worked with house wiring like RF TV wiring or phones, there are tons of crimp connectors, F-type connectors etc. which are loaded with non-conductive silicone grease (for weatherproofing), and these all work fine despite the tiny contacts and low pressures.

 

Those RF connectors are loaded *after* connection.

On the other hand conductive grease is used between conductive surfaces
and is required by the electrical code under certain conditions. Ask any
licensed electrician.

 

A good crimp connection involves deforming the two metal parts slightly to create a gas-tight metal-to-metal bond. Good crimped connections are actually superior to soldered connections for the transmission of critical signals. The problem with applying any non-conductive grease prior to the crimp (or tightening the battery post terminal, which is essentially a crimped connection), is that there is no guarantee that the grease will be adequately displaced for good metal-to-metal contact.

I think your intepretation is correct: Jaguar's recommendation is to apply grease only to the "base" of the post, which must surely mean the round ring of metal exposed by the opening in the plastic battery housing - it can't possibly mean any part of the vertical cylinder of the post around which the terminal is clamped.

For years I have been applying dielectric grease to our battery terminals and post bases and tops after tightening the freshly-cleaned terminal onto the freshly-cleaned post, and I've had very few problems with corrosion since. I think next time I'll try applying a little grease to the post base before I install the terminal.

BTW, I don't believe in using dielectric grease on any sensitive electrical contacts. I use it to seal the two plastic halves of electrical connectors, but not on the conductors themselves. By definition, a dielectric material is an insulator that can store a static electric charge (like a capacitor), so I'll use it on light bulb bases but never on sensor connectors or other sensitive circuits.

Cheers,

Don