opinion on conductive vs dielectric grease for contacts - Page 1
Forum section: electronics / general

author: coppercone2
author_rank: Super Contributor
timestamp: June 03, 2019, 01:49:05 am
content: https://www.w8ji.com/dielectric_grease_vs_conductive_grease.htmfor a car battery, should I usehttps://www.amazon.com/MG-Chemicals-Carbon-Conductive-Grease/dp/B00SMRNSR0or, a regular dielectric grease that is sold in a autoparts store (i.e. CRC )https://www.crcindustries.com/products/technician-grade-dielectric-grease-3-3-wt-oz-05113.htmlDo you share the opinion of w8ji?for those with deep pockets,https://www.amazon.com/MG-Chemicals-Conductive-conductivity-Dispenser/dp/B005T8QLYM/ref=pd_bxgy_328_3/138-1858492-6318017?_encoding=UTF8&pd_rd_i=B005T8QLYM&pd_rd_r=dc84a470-85a1-11e9-b428-7d17b7108ea6&pd_rd_w=UzxdE&pd_rd_wg=f2d8r&pf_rd_p=a2006322-0bc0-4db9-a08e-d168c18ce6f0&pf_rd_r=WMFZS9JQ91CQHWA7S743&psc=1&refRID=WMFZS9JQ91CQHWA7S743DO you think it will make a difference in the long run? I figure using the cheap stuff, cleaning the terminals with a brass brush and contact cleaner is a wiser decision ?Do you think harm can come of the conductive grease in automotive car battery applications (not on the spark plugs)?

author: Ian.M
author_rank: Super Contributor
timestamp: June 03, 2019, 02:52:19 am
content: Good article.Points to take away from it:* The purpose of electrical grease is to exclude air and moisture from between the contact surfaces, preventing corrosion and reducing oxidisation, and in the case of wiping contacts, lubricate them. If there is adequate contact pressure, and the grease is of suitable viscosity, it is totally squeezed out from the peaks of the surface roughness where metal to metal contact actually occurs, so doesn't affect the flow of current.* Using so-called 'conductive' greases risks insulator surface breakdown unless you are extremely careful with their application. If it isn't a bolted joint between dissimilar metals, with one or both of them prone to corrosion or serious oxidisation, you probably shouldn't be using it*.* Silicone grease is unsuitable for contacts liable to arcing, i.e ones that break under load carrying significant current, due to the risk of abrasive particles forming in the arc. For other contacts its generally preferable to hydrocarbon greases.Consider your battery connection: A lead alloy post with a bronze, brass or plated steel clamped on terminal. First the contact surfaces must be absolutely clean and fit together properly. Just about any grease will do to exclude air and moisture if its got a wide enough working temperature range. It therefore comes down to what's convenient and least messy. Carbon loaded grease is about as messy as you can get, increases the risk of corrosion, and is liable to cause surface tracking on insulatorsBe very careful with silicone grease if you expect to need any paintwork done on the front end of the car in the next few years as its a right b****r to remove all traces of silcone contamination before painting and even a missed fingerprint contaminated with silicone grease will result in 'fisheyeing' and a failed paint job.* OTOH for electrical jointing of dissimilar metals to aluminum, IMHO if you aren't using 'Noalox' or equivalent, you are setting yourself up for expensive failure.

author: coppercone2
author_rank: Super Contributor
timestamp: June 03, 2019, 02:54:50 am
content: yea actually I noticed one of the kitchen lamps has aluminum wiring bonded to copper without grease meant for that sort of bond (sold in lowes next to the CRC, was wondering WTF its for because the packaging does not tell you)

author: Gyro
author_rank: Super Contributor
timestamp: June 03, 2019, 08:08:49 pm
content: I'm sure I've expounded its virtues before - but it's really hard to beat good old Vaseline for all (well most) of the above applications, and a few more!

author: floobydust
author_rank: Super Contributor
timestamp: June 03, 2019, 08:37:58 pm
content: For over 10 years now I use silicone dielectric grease on my car battery terminals to prevent corrosion. It works great.Before that I used ordinary (car) grease and hot weather made it run off onto the battery and then a mess with dust and dirt.Some mechanics use spray paint on battery terminals.Every year or two, I wire brush the posts and inside terminals. Motor cranks faster so something causes the connection to degrade. I think it's the lead and plated straps that go on the posts, dissimilar metals.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 04, 2019, 10:39:11 pm
content: Interesting article and discussion; bookmarked.In joeqsmith's multimeter thread there is a discussion about grease on Fluke and other DMM's rotary switch.

author: Someone
author_rank: Super Contributor
timestamp: June 04, 2019, 11:04:18 pm
content: Quote from: Gyro on June 03, 2019, 08:08:49 pmTo be complete, the vaseline is applied liberally after the battery terminal and connection is cleaned, seated, and tightened to full torque.

author: floobydust
author_rank: Super Contributor
timestamp: June 05, 2019, 06:52:57 am
content: I don't think Vaseline (petroleum jelly) is suitable for some climates because it has a low melting point.It is a paraffin wax and mineral oil blend. For skin care, it must be just above 37°C but industrial types are around 54°C or 130°F.Silicone grease does not melt.

author: Gyro
author_rank: Super Contributor
timestamp: June 05, 2019, 10:51:09 am
content: No it doesn't remain as a solid 'buttering' of Vaseline on the battery terminals, it melts down to a slightly oily looking surface. The important thing is that the metal still doesn't corrode, even after several years of under-bonnet (hood) exposure.