Classic cars forum & vehicle restoration.

[Rich5ltr]

I cleaned the earth terminal on the Aston today. Over the winter it had built up a really bad case of verdigris but more interestingly under the usual salty green deposits was a hard solid dark red build up. I was able to chip it off and clean up the terminal but does anyone know what it was, causes this and how I can prevent it?

The car is on an Accumate and I always clean the terminals and apply a smear of Vaseline on them before fitting them back but it always seems to return.

[47Jag]

Rich,

I believe that the deposits are copper oxide and are a by-product of the electrolytic effect between the brass terminal and the lead battery post. the electrolyte being the sulphuric acid vapours given off during charging. IMHO by using the battery conditioner/charger you are exacerbating the problem. I've noticed that modern sealed top/externally vented battery terminals don't corrode. Try immersing the (disconnected) terminal in a strong solution of baking soda and water to remove all traces of corrosion then apply the Vaseline.

Art

[Rich5ltr]

Interesting thoughts Art. I will definitely clean the terminal with baking soda as you suggest. But are suggesting it's the Accumate that causing the problem? I guess I could leave it off and simply give the battery an occasional charge? I have a similar charger on the TVR but it's connected to the cigar lighter and causes no problems at all. Perhaps if I connect up somewhere else away from the actual battery?

[kevin2306]

I use a battery conditioner on the mazda with no effects, I was wondering if it was down to a poor earth?
I use contralube on all my terminals/connectors, before that i used to use vaseline

Kev

[47Jag]

Rich,

Is the TVR negative earth by any chance?

Kevin, Your Mazda will be.

What happens with negative earth car is that the wiring (which is positive) corrodes. Which is why we get so many strange problems with modern cars.

Art

[goneps]

I had this problem for years with the old rubber-cased 6v battery that'd been rebuilt with new cells a couple of times (can't get rubber-cased batteries in NZ). On the second rebuild the battery man couldn't get new pitch to seal the top, so had to re-use the old pitch and it didn't seal well around the terminal posts. Changed to a new plastic-cased battery a couple of years ago, and there's been no sign of the dreaded verdigris since. Acid fumes seeping up around the terminals were causing the problem.

Incidentally, during the life of the second rebuild the car was converted from positive to negative earth (as originally used on pre-war Morris cars), and that made no difference whatever to the verdigris problem.

Richard

[Rich5ltr]

Yes, the car is +ve earth but as a test I have moved the croc clip from the Accumate for the +ve lead away from the battery and clipped it on a post on the isolator which is about 12" away from the battery. Be interesting to see if that solves it.

ETA so far so good, moving the earth croc-clip away from the battery might have done the trick.