I have used the felt washers under the battery terminals for years,
replacing them when they dry out.
I also spray the terminals and connectors (after attaching and tightening)
with silicone spray.
I have had no problem with corrosion.
Jerry

----- Original Message -----
From: "Dave Mcneely" <mcneely4@COX.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Wednesday, March 17, 2010 6:54 AM
Subject: Re: Cause of the white corrosion deposit around a battery?

> to more completely answer the question, I believe the deposit is metal
> sulfate produced when sulfate condensate  from the battery comes in
> contact with metal.  Either grease or oil will prevent it.  If you want to
> get fancy, most battery vendors sell little felt circles impregnated with
> a substance that blocks the corrosion from developing.  Just slip the disc
> over the post and tighten down the clamp.  They come in red for the
> positive post, green for the negative, and they work.  If you do use oil
> or grease, remember to tighten the clamp down before greasing the post, of
> course.  There is also a special material sold in a squirt can.  It coats
> the terminals with a purplish plastic like substance that also blocks
> condensate and air from the terminals but in no way prevents clamp
> removal.
>
> So far as only the positive post corroding, I believe the sulfate can
> condense on any surfaces in the vicinity of the battery.  In extreme
> cases, the entire support system for the battery will fail.   If the
> corrosion were from oxygen rather than sulfate, then on  steel parts, the
> substance would be rust red.  Now, eventually such parts do rust, if the
> sulfate corrosion doesn't get them first.
>
> In the simple case, perhaps the lead post itself is corroded with a simple
> lead oxide, but when the corrosion is over other parts, it is metal
> sulfate.
>
> DMc
>
> ---- Tom Hargrave <thargrav@HIWAAY.NET> wrote:
>> It's corrosion and should only be on the positive terminal.
>>
>> Sometimes you have a leaky seal around a post but this is rare these
>> days.
>> More often the corrosion is because the + side of the battery attracts
>> oxygen ions from the air and the oxygen interacts with the metal, causing
>> the corrosion.
>>
>> There are a lot of "fixes" you can buy but the best one is to put a drop
>> of
>> oil on the terminal every time you check your oil. The oil will spread
>> out
>> into a thin film & will protect the terminal from corrosion.
>>
>> Some people put grease on the terminals. Grease will also work but you
>> need
>> to make sure to cover the entire terminal, even the bottom edge of the
>> clamp. If you don't then any exposed metal will corrode.
>>