What To Do With Battery Corroded Contact? - Page 1
Forum section: electronics / general

author: Boris_yo
author_rank: Frequent Contributor
timestamp: December 15, 2012, 11:57:52 am
content: One the picture you will see a hair trimmer's compartment after its leaked battery was taken out. The contact lead which is supposed to be minus for battery looks dark blue now and I have tried several working batteries, all to bo avail. I heard that consumers should take care of their electronics and remove batteries if electronic is expected not to be used for a while. Although in my case I apparently have failed to follow this advice, I still would like to know if something can be done.

author: Astroplio
author_rank: Regular Contributor
timestamp: December 15, 2012, 12:05:22 pm
content: hello,check also this thread:https://www.eevblog.com/forum/chat/fluke-187-corroded-battery-terminals-how-to-clean/I hate so much when this happens...

author: TerraHertz
author_rank: Super Contributor
timestamp: December 15, 2012, 12:29:46 pm
content: Funnily enough I recently repaired a pile of old Sega Lock-on 'laser tag' game units, that mostly had problems like this.If you can remove the metal battery contact from the unit, and the corrosion is only on the surface (ie most of the metal is still there) you can repair it. But it's going to be tedious.Once you get it out, remove the attached wire. If the battery chemicals got to the solder the solder will be hard and brittle, and won't want to melt. Scrape some of the surface of the solder clean, then add new solder. This lets you get heat to the joint, and you can separate the wire then whack all the old solder off. (How: Hold metal contact in pliers, heat joint with soldering iron, add some new solder, then quickly rap the part sharply on the bench. All the solder is shaken off. Wear eye protection!)Completely replace the wire with new - the battery chemicals like to wick up inside the insulation, and not only is the wire now brittle and a source of re-contamination, but you can never solder it.If the spring contact is salvageable, just sit down for a while with an exacto knife, and firmly scrape all the crap off the surfaces. Little bits of sandpaper can also help. It's likely the nice chrome or nickel plating will be gone, but it doesn't really matter.Once it's scraped clean, wash it with hot water and detergent, steel wool pad, whatever. The aim is to remove whatever remaining surface contamination you can.Before you mount it back in the plastic case, attach the new wire lead. The metal won't be as easy to get the solder to bond as it was when it had a nice clean plating, but since it's free of the plastic you can apply as much heat as you need.Now the wire is attached, one last step. Coat all surfaces of the metal with something greasy to inhibit further corrosion. There will be ions from the battery chemicals that have diffused into the metal, making it more prone to corrosion than before. The grease stops that. I usually use vaseline (petroleum jelly) but I'm sure there's probably something better.Then reassemble. And don't leave batteries in things for long idle periods, as you're now aware.Oh, one last thing. As the battery contact point you scraped clean is maybe now bare brass or iron, you might be tempted to solder-tin it to 'improve contact'. Don't do it! Solder surfaces make terrible resistive contacts, since the lead oxidizes, and also rubs off to produce a film of non-conductive particles. Just keep the contact point greased to stop oxidation, and maybe buff it with some emery paper now and then. At least it works.And at least it looks like you don't need to go hunting for replacements for the 'coil spring' end of ruined battery compartments. Like in a lot of those blasted Lock-on things.

author: SeanB
author_rank: Super Contributor
timestamp: December 15, 2012, 12:44:12 pm
content: I keep old remotes around as a source of those little wire springs....... Funny how many you can find for under a buck a dozen at flea markets.

author: G7PSK
author_rank: Super Contributor
timestamp: December 15, 2012, 02:18:01 pm
content: Blue will most likely be copper sulphate, should clean off with a bit of soap and water and a stiff brush or a scotchbrite pad.

author: RCMR
author_rank: Frequent Contributor
timestamp: December 15, 2012, 08:56:57 pm
content: As others have said -- get rid of all the corrosion (by whatever means best suits) then you can tin the bare metal that remains so as to stop further corrosion due to oxidation of the bare metal beneath.I've actually gone as far as to use electroless nickel plating to repair the contacts in really important bits of kit that have come into my hands after being considered "faulty" due to corroded battery contacts. The only problem I find with using solder as a contact material is that it too does oxidise and can cause high-resistance between battery and contact. Electroless nickel stays bright and shiny.

author: TerraHertz
author_rank: Super Contributor
timestamp: December 17, 2012, 12:02:00 am
content: Care to offer any information on how to do electroless nickel plating? Or do we have to google it?

author: SeanB
author_rank: Super Contributor
timestamp: December 17, 2012, 04:31:58 am
content: Not really electroless plating, more a case of plating without a bath, using a soaked cotton swab to provide the solution to do selective plating in an area of metal. You do need a connection and a sacrificial anode, either carbon or the nickel.

author: TerraHertz
author_rank: Super Contributor
timestamp: December 17, 2012, 05:05:04 am
content: Oh, you too with the link-less teasing about how easy something is. Except for people who have virtually no knowledge of chemistry.Well, I'll add it to the long list of things to look up when I have time.Here's something related- electrochemical cleaning of stainless steel TIG welds.TIG Brush Stainless Steel Weld Cleaning Systemhttp://www.ensitech.com.au/The system costs too much for me to afford atm, though I could really use such a thing. So, looking into it to see if it's possible to improvise.in this clip the ensitech guy mentions that liquid is phosphoric acid.Closeup of bottle says TB25 - also says phosphoric acid. No concentration mentioned.Its the red liquid.http://www.tigbrush.com/Admin/Uploads/Ensitech-TB-25-TIG-Brush-Weld-Cleaning-Solution-Aust-Nov2008-web.pdfTB-25 Material Safety Data Sheet mentions ~1% each of two proprietary additives.http://www.tigbrush.com/The sales arm of ensitechTB-25 liquid is $65 for 1 litreTBX-300 TIG Brush® Kit (Australian model) $3,500.00Would anyone happen to know how to do this using known, available chemicals, and with a specified voltage/current/waveform?I wouldn't be surprised if a standard TIG welder with AC/DC options can generate the required electrical drive.[edit: Hmm, I really didn't want to embed those videos. That slows the page load, and is too much like free advertising. Is there some way to make a link just appear as a link, regardless of whether it's to a video?]

author: SeanB
author_rank: Super Contributor
timestamp: December 17, 2012, 05:59:42 am
content: When I was an Apprentice there was a manual for a Dalic plating system in the shop. just the manual, the equipment was not there any more, so i did read it cover to cover, very interesting.