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NOOOOO! i'm an idiot

N

NothernMystique

CEG'er
Joined
Oct 21, 2004
Messages
129
Location
Toronto, Canada
I was having some trouble with my car, most of the time it would be fine, howver after it rained i found it would not start. Now, I've also been driving and the car would just stop, die, show no power, all the lights were dim I'd be driving and the car would just die. So, I checked through the starting circuit and reconnected the ground that looked all corroded. And when I got home it started no problem. I took it to work, and when going for lunch, it died. while driving at 2500rpm.

I got it towed (my 3rd tow this year) and the dealer says.... You have a bad negative terminal connection, there is some grease in there preventing the connection. Now, I can recall looking at the battery terminal usually nice and clean in the trunk and seeing some corrosion on the negative terminal. I put a bunch of dielectric grease on there and thought it was good to go. Little did I know....DIELECTRIC GREASE IS NON-CONDUCTIVE!

Now, have you guys ever run into a problem with this stuff? I use it on my spark plug connections with no issues. What's up here?

I'm also going to post in the general trouble shooting because I'm afraid the diagnosis is too good to be true and there are a few clues that I need some advice on.
 
I use Dielectric grease on all of my connections. its on very thick on my battery terminals. I have never had any issues. i use it on 4 different cars that my family owns.
 
Dielectric grease is a good way to keep water/dirt out of things when put on a connection...it's not going to do anything to improve the conductivity of your connections though.
 
I believe MEAN_TOUR had a similar problem. He ended up throwing a ton of money at the car to diagnose the problem, but never got anywhere.
He ended up selling the car to another member who found dialectric grease was the problem.
A real kick in the nuts.
 
its interesting, I use dielectric grease on my car when I cleaned all the ground and it didn't seem to make a difference. although I do recall some slight issue and that I cleaned it off the main battery ground in the trunk, otherwise it wasn't a big deal.
 
The way its supposed to work . . . is die-electric grease is supposed to prevent water and ultimately corrosion from getting into the electrical connection. It is non-conductive by design, (hence the name die-electric). I suppose using way too much of the grease directly inbetween the two contacts could create an issue, but it would have to be pretty significant amount of grease and a gap between the connection points, or there is another issue someplace else, and the extra grease is simply "the straw that broke the camel's back" . . . by increasing the resistance just a little too much for the system to handle.
 
I've always been of the understanding that dielectric grease "IS CONDUCTIVE".And that it can be used on ANY electrical connection. I seam to recall using it on a few ignition control modules for conductiviny and heat displacement. :shrug:
 
Dielectric grease (or dielectric ANYTHING) is an insulator (non-conductive) under most conditions.

Apply a high enough voltage, though (depending on the material) and it becomes a conductor while it's in it's shifted state.

The dielectric grease you use for heat sinks in electronics is non-conductive. Transistors really wouldn't like it otherwise.

If used on a battery terminal, it's a crapshoot. If it's thick enough on the connection, it will interfere with the electrical path. Used thin enough, there's enough of a metal on metal connection on the rough spots on the terminal and stud to make a good connection.

That's why they make application specific coatings (like the earlier mentioned red crap you spray onto the terminals.....works wonders, but then again so does anything normally used as intended)
 
I've always just cleaned the terminal, tightened it back down and then applied grease to the exterior to keep it happy.
 
Rara said:
The way its supposed to work . . . is die-electric grease is supposed to prevent water and ultimately corrosion from getting into the electrical connection. It is non-conductive by design, (hence the name die-electric). I suppose using way too much of the grease directly inbetween the two contacts could create an issue, but it would have to be pretty significant amount of grease and a gap between the connection points, or there is another issue someplace else, and the extra grease is simply "the straw that broke the camel's back" . . . by increasing the resistance just a little too much for the system to handle.
Click to expand...

Well, I know that now.... i had it all over the terminal then put the connector on... nice thick layer.. So now I'm thinking that the HOT terminal was a result of the insulation..

what do you think
 
Bingo.

Resistive connections heat up. (One of my favorite toys at work is the thermal imaging camera......shows bad connections in a heartbeat, even on a 5v low amperage line)

Get a heavily resistive connection that has a lot of amps going through it (IE a 100+ Amp terminal connection that's gone or sent resistive), and you have a toasty terminal.
 
gone postal said:
Bingo.

Resistive connections heat up. (One of my favorite toys at work is the thermal imaging camera......shows bad connections in a heartbeat, even on a 5v low amperage line)

Get a heavily resistive connection that has a lot of amps going through it (IE a 100+ Amp terminal connection that's gone or sent resistive), and you have a toasty terminal.
Click to expand...

Ditto that Bingo. What this guy said exactly, except you don't even need 100+ amps for the terminal to start to get warm depending on the size.

Shoot, I've used a cold frosty morning on several occasions to located voltage drains on cars . . . look for the spot with no frost and that will tell you what interior light isn't shutting off, lol. (Usually underhood or trunk light for something like that)
 
You don't need 100 amps, we find bad 0.5A/5VDC lines all the time with the camera. Makes like a hell of a lot easier trying to find odd power problems.

Which gives me an idea.....

I wonder what a 2.5L looks like in IR?
 
I'd love to try it, just for the hell of it. Maybe I'll try it with my POS some fine evening.
 
I'd love to see how my 4L looks when it pegs red (265) on a hot day and no working auxiliary fan. :laugh:
 
Stop into the Binghamton PO some fine night and I'll check it out!

(Would've taken a picture of my POS last night after I got to work, but a $25000 thermal imaging camera and rain just wouldn't mix)
 
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