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How to Arrest Corrosion of 41CV battery - Printable Version

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How to Arrest Corrosion of 41CV battery - bill platt - 10-28-2003

Well, I pulled my 41CV fullnut back out the other day to take a look at maybe trying again to get the broken post thing fixed. When (6 months ago) I got the unit, the battery contacts were pretty badly corroded, and there was even a little bit of turquoise bloom down at the CPU zebra connector. I cleaned it all up at the time with rubbing alcohol, and got everything nice and shiny. Then, she worked for a bout 2 weeks, and quit again. (Turned out to be a broken post).

So, now the turquoise is back :-{ And I wonder what is an appropriate neutralization--should I perhaps make a dilute baking soda solution and carefully dab that on all the corrosion? If it keeps re-blooming, then no amount of fixing is ever going to be satisfactory.



Re: How to Arrest Corrosion of 41CV battery - Nelson M. Sicuro (Brazil) - 10-28-2003

I use citric acid (lemmon juice) with a bit of salt. It takes the blue oxide off very easy, but you need to wash it after - as it is an acid, it will corrode things also! I cleaned a TI 2550 *badly* corroded battery terminals, and now is very clean and the blue oxide doesn't appeared anymore.

Re: How to Arrest Corrosion of 41CV battery - David Smith - 10-28-2003

I have a friend who does conservation of antiquities, etc. She has talked about "corroison centers" forming on items. They are like little cancers from which all things blue and green grow. They can be almost impossible to kill. Clean things up and the green fuzzies invariably return.

I have been treating my green fuzzies with Caig DeOxit and Pro Gold pens. Seems to help.

Re: How to Arrest Corrosion of 41CV battery - Ed Look - 10-28-2003

Gentlemen, corrosion is a complex redox phenomenon. And battery discharge is also redox based, as well. That is to say that Mr. Smith is absolutely correct that it is technically impossible to arrest corrosion. Besides, we live in an atmosphere of 20% oxygen. Metals tend to corrode. One possible trick in addition to keeping your contacts scrupulously clean with frequent inspections is possibly do what you might do to a jack o'lantern to keep it fresh a few more days- put a barrier film of some oil or grease (thin! Did I say thin?) on the metallic surfaces that are exposed to air or are in contact with batteries, like the way you might oil a hand tool to keep it from rusting. Be careful that the protectant used is not flammable (toxic is okay; who eats calculators? ;) ). But if you find you have to remove oxide, a little fine sanding or scraping is okay. Using more acid to remove it may compound the problem in the long run, as the oxides are generally unreactive to acids and they come off because you are removing the metal layer below it. But after sanding or scraping, if you can somehow protect that clean surface, all the better.

Re: How to Arrest Corrosion of 41CV battery - Ed Look - 10-28-2003

Oh, also hope the protectant barrier does not react with the metal when current is passed through!

Re: How to Arrest Corrosion of 41CV battery - cyrille de Brébisson - 10-29-2003


Actually, do you know any company that does HP41C repairs?

regards, cyrille

Re: How to Arrest Corrosion of 41CV battery - Marx Pio - 10-29-2003

I think most of us did or is doing some kind of repair on our old HP´s. Maybe we can create a company in the near future. We can call it [(ph)]. Parts & Handling. ;)



Re: How to Arrest Corrosion of 41CV battery - bill platt - 10-29-2003

Hello Cyrille,

Very nice to have the chance to say hello!

Yes, There is a link here at the museum under the repairs or something section:


Also, you will see Randy Sloyer's posts---he is the "company".

Best regards,