Cleaning corroded battery contacts in radios etc

[stevehertz]

Cleaning corroded battery contacts in radios and battery operated equipments due to battery leakage. The idea is to neutralise the acid corrosion using an alkali such as common baking soda. However, just double checking the procedure on Youtube, a guy was saying that if the batteries are alkaline, then you should neutralise the corrosion using an acid such as vinegar. Makes good sense to me, but it somewhat complicates the issue if you don't know what type the batteries were that caused the corrosion. Make the wrong guess and you're 100% wrong, kinda adding to the corrosion! What's you take on the issue? Should you defo match the 'cleaner' to the battery type, or is it safe to use baking soda in every case? It's an interesting point and one that I'd never thought about before!

[Radio Wrangler]

Even if you use the right stuff, do you use the right amount to neutralise the amount of leak? If you overdo it, you go the other way.

I just go for lots of dilution through washing and rely on a bit of added detergent to improve washing.

David

[richrussell]

I too just rely on physically removing as much as possible then using a neutral solvent (meths, IPA or occasionally WD40 depending on what I've got around). For really stubborn corrosion, then the small files and/or sandpaper come out.

With no idea what chemicals caused the corrosion, I don't bother trying to neutralise it.

[stevehertz]

Yes, I agree. I just cleaned a spring contact out of a Sony ICF-403L portable radio. I unsoldered it, held it in a pair of small round nosed pliers and brushed the corroded end of the spring with a brass brush until all signs of corrosion were gone and it was shiny metal. I then resoldered the spring back in place and using a cotton bud, applied Servisol to the spring contact to further improve electrical contact, and provide a degree of protection against further corrosion. As you'd expect it all works fine now, and there's no lingering concerns about acid or alkali getting into the works. I suppose there are times when a mechanical clean is not so easy due it not being possible (or very difficult) to remove the contacts for cleaning away from the equipment. But even then, in the past I've always done my best using mechanical methods albeit awkwardly. Our Youtube friends prescribe daubing the chemicals somewhat liberally in battery compartments using a doused cotton bud. Of course, don't believe everything that you read (anywhere), or see on Youtube!

[TonyDuell]

I do normally clean up NiCd battery leakage using citric acid solution (it smells nicer than vinegar). That is known to be an alkaline electrolyte (mostly KOH).

Quite often it's a backup battery that has leaked onto a PCB. Carefully applying the acid then washing with water (lots of it), then propan-2-ol seems to get it clean again. Never had future problems.

With a seprate battery holder taking user-replaceable cells, I would probably take out all the metal contacts and clean the plastic with whatever works (these chemicals are not strong enough to damage the plastic, I think). If necessary I would replace the contacts, battery holders from e.g. Maplin are a good source of springs....

[G6Tanuki]

The issue I generally find with battery-exudate-corroded contacts is that it either eats-through the [steel] spring, or selectively robs the zinc from brass, leaving behind a terra-cotta-coloured and often rather embrittled copper matrix of questionable future reliability.

Where possible I prefer to replace the corroded parts (even if it incurs cost or engineering-effort) rather than just clean them up.

[ColinTheAmpMan1]

If there is any liquid residue in the battery-holder, a quick check with pH paper would give a good idea of whether you are dealing with acidic or alkaline leakage. Anything below pH 7.0 is acid, over pH 7.0 alkaline. If there is no liquid residue, a liitle of any solid residue could be removed, dissolved in water and again checked with a pH paper. If you don't have as easy access to pH paper as I do (I am an occasional research chemist), then a friendly pharmacist could be approached. You might even find that the pharmacist makes a gift to you of a little of the appropriate pH paper.
Colin.

[Refugee]

I good place to find PH paper it to ask someone whom is diabetic.
They use them regularly.

[mole42uk]

I've always found that vinegar is the right stuff for primary cell leakage, followed by copius amounts of tap water. Treat de-plated or terminally corroded contacts as appropriate, either replacing or polishing them.

[broadgage]

All common small battery types use an alkaline electrolyte, this applies to zinc/carbon, nickel/cadmium, alkaline, nickel metal hydride.

Therefore in theory a mild acid such as vinegar or citric acid is called for.

In practice though the leakage has normally reacted with the surrounding materials and with carbon dioxide from the air to form chemically neutral metal salts and carbonates.

A mild acid still seems to work well.

[Dave Moll]

The acid can work by dissolving the salts, especially if its own salts are water-soluble, rather than by neutralising any alkali.

If you really want to test pH, universal indicator papers are cheaply available through the likes of eBay - other sources are also available, though they won't work dry.

[Herald1360]

A good mechanical clean followed by hot water rinse then meths to help drying. Then a good smear of silicon grease to stop further corrosion due to the lack of protective plating. Silicon grease is good stuff if a bit of mess isn't a problem- it'll even keep salty water out of cleaned up pitted sidelight bulb holders!

[ColinTheAmpMan1]

Originally Posted by Dave Moll

If you really want to test pH, universal indicator papers are cheaply available through the likes of eBay - other sources are also available, though they won't work dry.

I think my post was suggesting that the residue either needed to be wet, or if dry, to be dissolved in a little water. Maybe I didn't make it clear. The definition of pH is "the negative logarithm of the hydrogen ion concentration."
I suppose that familiarity breeds contempt, but I assumed that everyone would understand that this would be a concentration in aqueous solution.
Colin.