Re: Corrosion caused by batteries.

[Jim Davis <alarminex@xxxxxxx>]

On Tuesday, November 12, 2019 at 12:27:41 AM UTC-5, cha...@xxxxxxxxx wrote:
> I am getting fed up with the corrosion at the negative or positive
> terminals of Duracell AA and AAA batteries that come preinstalled
> (from the manufacturer/distributor) in wireless motion detectors and
> door/window contacts, as well as corrosion within the devices after a
> year or two on the job site, all residential.
>=20
> Are there any tricks to prevent corrosion? Vaseline, jells, etc? Does
> anyone have a clue as to the root cause of corrosion? I know that
> water/high moisture is a prime catalyst especially on door switches
> that are near the bottom of an exterior door. Does the passage of
> voltage from the battery to the battery holder have an effect, and if
> so, how? It's also obvious (duhhh)that if the battery(s) are absent
> from the battery holder compartment there is never any corrosion in
> the holder.
>=20
> Charlie

With regard to your question about the source of the corrosion =3D=3D=3D=3D=
 again drawing from my boating experience ---- Boats, particularly in salt =
water have to have what are called sacrificial zincs installed on any metal=
s that are submerged in the salt water. Such as propeller shafts, rudders, =
water intakes, etc. Also, all metal objects that protrude through the hull,=
 into the water must be connected inside the boat with a common wire. If th=
is isn't done  what takes place is Galvanic corrosion.=20

If you put a electrolyte (salt water) between two dissimilar metals within =
close proximity to one another =3D=3D=3D if the metal objects have the slig=
htest difference in electrical potential, the object with the highest elect=
rical potential will lose it's substance ion by ion and be attracted to the=
 object with the lowest potential (cathode) resulting in a "corrosion" of t=
he object of the highest potential.=20

In other words electro-plating=20

However, even if there is no difference in potential, the metal with the gr=
eatest "nobility" will lose it's ions to a metal in close proximity of lowe=
r "nobility" in the presence of some sort of electrolyte or if touching one=
 another.

In your case the moisture in the air is the "electrolyte" and how long the =
battery (anode) is in contact with the battery clip (cathode).

Just an aside =3D=3D=3D you'll note that most/all battery clips are "shiny"=
. This is because stainless steel is very low on the "nobility" list and is=
 a good way to reduce the Galvanic process. So it's likely that the quality=
 of the stainless steel clips are a factor also.=20

This is also the reason that the small lithium button cells are stainless. =
Since they last so long, they would corrode if they were made of a more "no=
ble" metal.


Try the Silicon or Vaseline. It will likely last as long as the battery but=
 as I say, it's messy especially when changing batteries.