Re: (ET) Dielectric grease

["David Roden" <etpost drmm net>]

On 12 Oct 2009 at 12:44, RALPH VOGAN wrote:

> I use KOPR-SHIELD CP8-TB Conductive Anti-Corrosive Surface Compound,
> by Thomas & Betts. 

Thanks, that's the copper-based stuff I was thinking of.  Here's what one 
of 
the EVDL folks wrote about it several months ago (we talk about these 
sorts 
of things pretty often over there).

----- begin quoted text -----

Kopr-shield is a grease that has a fair amount of microscopic copper 
particles added in.  If you insert your meter probes into a glob of it 
you'll find that it has a lot of resistance.  How much resistance depends 
on 
film thickness.  Apparently the copper particles are not in intimate 
enough 
contact to create a low resistance current path.  For this reason I don't 
recommended it as an interface between connectors and cables in a system 
where you desire minimum resistance, such as the HV circuits in an EV.   
If 
you do choose to use it within a connection, use a VERY small amount and 
squeeze the heck out of it!  

Ok then, what about the corrosion protection that we want for those 
connections?  The tried and true method for creating good connections is 
to 
clean the parts of any oxides before connection, then, after mechanically 
fastening the clean bare pieces together (hex crimping, bolting, etc.), 
shield the OUTSIDE of the connection. This can be done with sealant lined 
shrink-tube in the case of cable/lugs, or by smearing something such as 
Vaseline over the outside of the mated pieces in the case of fastened 
together surfaces.   Save the Kopr-Shield for lower voltage/lower amperage 
connections.  

Richard Rau
Northwest Electric Vehicles

----- end quoted text -----

In addition to good old Vaseline, I've used some glop that came in a spray 
can with one of my packs of US Battery batteries.  That worked nicely too. 

Someone else on the EVDL years ago mentioned that he paints his battery 
terminals with enamel, and I remember yet another person suggesting that 
rubbery stuff that some folks dip tool handles in.  

Yet another suggestion: "I've found, by far, the best thing to use on 
battery terminals and lugs is $3 a tub high temp bearing grease.  You 
don't 
need much, just whatever a disposable acid brush will put on the terminal 
and lug.  I also put it on the lug's pinch bolt and nut. The bearing 
grease 
repels moisture very well, and won't run readily or dry out to a crust 
when 
heated.  The point of the treatment isn't to improve conductivity, but to 
retain the level of conductivity you have over temperature excursions and 
moisture exposure."

Mike Brown of Electro Automotive has used Noalox for many years.

I suspect that at the currents we use in ETs, just about anything that 
keeps 
moisture out will work fine.  


David Roden - Akron, Ohio, USA

= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 
Note: mail sent to the "etpost" address will not reach me.  To send 
me a private message, please use the address shown at the bottom
of this page : http://www.evdl.org/help/
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =