Always Clean the Negative

[SeniorCitizen]

I always get amused at this one.

Why is it always recommended to clean and make sure the negative battery cable is tight when the positive is usually the one that corrodes?

 

[Jack17]

I always get amused at this one.

Why is it always recommended to clean and make sure the negative battery cable is tight when the positive is usually the one that corrodes?

Any battery terminal will corrode if the seal at the base of a lead post let go.

 

[bertsmobile1]

Because they both corrode.
One corrodes the battery terminal the other corrodes the battery post.
The you have a tightness problem.
Not tight then the post will arc to the terminal and quite quickly burn the entire post right off.
Power has to go from one side of the battery all the way round to the other side so both sides need a good clean & tight interface.

 

[reynoldston]

I always get amused at this one.

Why is it always recommended to clean and make sure the negative battery cable is tight when the positive is usually the one that corrodes?

I agree with you on this 100%, but also I don't see no big thing cleaning both cables. Not that big of a job and I always say start with the small things first. I do think that sometimes people over look the negative part of electrical repairs.

 

[bertsmobile1]

Just to be boring,
Any time two dissimilar metals are in contact a galvanic cell is produced
This is regardless of weather there is a battery involved or not
So if you have a Sn-Pb terminal lead connected to a Sb-Pb battery post and the insulation of the copper wire is fluid tight against the terminal no worries as you can not make a circuit.
In all other cases galvanic corrosion will occur.
This is why some grease their terminals which excludes moisture which is the electrolyte that completes the cell .
Now just the same as the stale fuel bit affects some a lot more than others, galvanic corrosion will be worse in some climates or even microclimates than others.
So those of you with Phd's in imaginary metallurgy will go "Bull poo" it has never happend to me where as every one who was awake during school chemistry classes will remember it it true.

And to be really boring if the metals are perfectly clean and brought together they will instantly weld as was found out early in the space race & led to vacuum welding and latter to electron beam welding which was fundamential in the manufacture of bodily implants like pace makers.
Google it facinating stuff, We had a lot of fun welding stuf together in college then taking them to service centres complaining the we could not get them undone ( suppose my new occupation is payback )

 

[Jack17]

If you take less noble and more noble metals, put them together, introduce some electrolyte and you'll get galvanic reaction. But how is Lead on Lead connection gonna corrode unless battery post is leaking Hydrogen that will carry some of H2SO4 with it that will slowly turn lead post and clamp to lead sulfate?

 

[bertsmobile1]

As Sols found out to his misfortune, oil aint oils. well leads aint leads aint leads.
The negative post will be 4% Sb the clamp will be 2% Sb, 0.5% Sn not vastly different alloys but different enough.
I don't see many lead terminals, most are brass or steel as the media who know nothing about metallurgy decided that all lead is the devis metal and any contact with it, even the sight of it will result in death.
The posative post is a different alloy by the way.
Next time you buy a new battery have a good look at the terminals and you will notice they are different colours.
One will be fairly shiny and tho other quite dull.
The + plates are made from a different alloy to the - plates and that carries on for the bus bars & terminal posts.

The mear act of doing up the bolt will cause a galvanic cell to be generated within the actual terminal itself.
But don't take my word, go to the battery university ( web site ) and read that.
It has a web page so it must be true :laughing: