How to Arrest Corrosion of 41CV battery


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.




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.


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.


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.


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



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

regards, cyrille


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. ;)




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,


Possibly Related Threads...
Thread Author Replies Views Last Post
  Battery Holder 41CV William Mabotja 0 586 11-28-2013, 01:46 AM
Last Post: William Mabotja
  aOT--Battery/battery contact care advice needed Matt Agajanian 0 657 04-24-2012, 07:35 PM
Last Post: Matt Agajanian
  Corrosion ... best way to remove? Gene Wright 6 1,153 10-19-2011, 04:23 PM
Last Post: Ethan Conner
  Heat staked keyboards with sticky, bouncy or corrosion present keyboard PCAs Geoff Quickfall 12 2,104 08-15-2009, 07:55 PM
Last Post: Geoff Quickfall
  HP 41CV Battery Question Chuck 3 923 04-05-2009, 03:23 PM
Last Post: Geoff Quickfall
  TDS 500K dead battery, pictures of the inside of the card and the battery. Geoff Quickfall 4 1,253 04-02-2009, 11:23 PM
Last Post: Geoff Quickfall
  28C corrosion Vincze 8 1,588 08-10-2007, 06:35 PM
Last Post: allen
  leakage/corrosion from lithium batteries? megarat 0 450 10-31-2006, 11:19 AM
Last Post: megarat
  How to halt green corrosion on HP45 copper battery contacts in battery bay? JaSon 1 634 07-01-2006, 07:27 AM
Last Post: David Smith
  HP-41CX damage from battery corrosion... Andreas Terzis 7 1,373 03-13-2006, 03:36 PM
Last Post: Andreas Terzis

Forum Jump: