Clean/Repair corrosion in battery compartment

Moopheus · Feb 22, 2017

This is battery compartment of a Spartus Co/Flash that I just picked up at the local antique mart. The camera is mostly in pretty good shape, except that when I opened the battery compartment for the flash there were two very old and corroded batteries in there. The tab on one end was badly damaged and just broke off. I think I can jerry-rig a connector to the clean part on that side, but I think I will need to try to clean up the other end some more. Anybody have an idea what might work here?

tedr1 · Feb 23, 2017

Looks like a job for a very small awl to break up the coating, followed with cotton bud moistened with water, and another with IPA, to remove the residue. Prevent the fragments and dust reaching the interior.

Pentode · Feb 23, 2017

You can neutralize the affected area with a water/baking soda slurry, then clean up with a fine brass brush.

darkroommike · Feb 24, 2017

Alkaline battery residue cleans up best with acid not baking soda, I use swabs with vinegar and then more swabs with water, works swell. The baking soda woks well with car battery residue which is acid (sulfuric).

AgX · Feb 24, 2017

Yes, Vinegar. Any residue vaporizes. BUT it may take with itself salts to other, hidden places.
And at those places salts may have established themselves in first place anyway. So there typically is the chance that corrosion may go further unseen. So disassembly is adventageous in many cases.

darkroommike · Feb 25, 2017

AgX said:
Yes, Vinegar. Any residue vaporizes. BUT it may take with itself salts to other, hidden places.
And at those places salts may have established themselves in first place anyway. So there typically is the chance that corrosion may go further unseen. So disassembly is adventageous in many cases.

I use just enough to moisten a cotton bud (Q-tip) and don't flood the battery compartment. And then several alternations of dry buds to blot and wet (with water) buds to dissolve residues. It can take a bit. Usually, if the corrosion is bad, the plating is gone but you can bring such devices back to life.

Truzi · Feb 25, 2017

Be careful when you "rinse" (as darkroommike says blot with water-soaked buds). Dry it very well as it may rust if you don't.

AgX · Feb 25, 2017

darkroommike said:
I use just enough to moisten a cotton bud (Q-tip) and don't flood the battery compartment.

I do the same. But once salty residue is at a slit or so, the vinegar to be effective likely will slip into that slit. And as said, likely the salt already had found its way there anyway and spread over some printed circuit in the past.

Pentode · Feb 25, 2017

darkroommike said:
Alkaline battery residue cleans up best with acid not baking soda

Thanks, I didn't know this. Makes perfect sense.

Gerald C Koch · Feb 25, 2017

When using white vinegar to clean the compartment you should follow up with a swab dipped in household clear ammonia. This will remove any trace of acid and will leave no corrosive residue of its own. In fact I would recommend trying the ammonia first. However the proactive solution is to always remove batteries when a camera is not in use.

AgX · Feb 25, 2017

The acid of the vinegar will evaporate in a few minutes. There is no need for bringing a second chemical into the game.

Moopheus · Feb 25, 2017

Some progress is being made. I've tried the vinegar-on-a-swab trick, and some of the corrosion is coming off the intact terminal. As a proof that the item is salvageable, I put in two batteries and dropped a copper penny (a 1940 penny, so I knew there was actually some copper in there) in the end with the broken terminal, and successfully triggered the flash. A penny won't actually fit inside the compartment, so I need to find something else to substitute for the broken end, but it can actually work again.

Yeah, I mean, I know not to leave batteries in for a long time, but this was an antique-store find, who knows how long the thing was in storage. Decades, judging by the batteries. One of them was a Mallory.

The Spartus is a molded bakelite one-piece body. Disassembly isn't really an option. Fortunately, the batteries are only needed for the flash. It takes M2 bulbs.

Truzi · Feb 26, 2017

You might be able to carefully solder a piece of metal to it, or perhaps use a conductive glue.
If you don't care how "original" it is, see if a battery holder/insert will fit the chamber, something like this:
Dead Link Removed
If the camera takes AA, perhaps a AAA holder would easily fit. You could solder the leads to the plates.

If what is left is like a "tab," you might be able to slide a small metal spring over it - some battery compartments have something like this to make sure the connection is solid and the batteries are tight.

I can't tell well from the photo, but are those contacts held down by small nuts? If the stud is solidly fixed, you may be able to simply replace the plate with one you fabricate yourself (assuming the nut/stud provides the electrical connection).

David Lyga · Mar 1, 2017

Even more extreme than vinegar: glacial acetic acid, but be careful!!! - David Lyga

John Koehrer · Mar 3, 2017

Pennies too big? try a dime.

Moopheus · Mar 10, 2017

After hunting around for a bit for a suitable material to make a new connector end with, I ended up with the very sophisticated solution of wrapping a bit of cardboard cut from the back of a notepad with some aluminum foil from the kitchen drawer and sticking the end of the foil down over the connector to reach the still-clean part. Totally elegant, but it works. I can stick the batteries in, close it up, and fire the flash. I got some expired 127 rolls to salvage the spools and backing papers from, so now I have to give it the live test.

Pentode · Mar 10, 2017

Inside a battery compartment, elegence is completely optional!

DWThomas · Mar 10, 2017

Hobby shops catering to model railroaders typically have an assortment of brass pieces (in the US via an outfit called K&S) -- tubes, both round and square, as well as strips in different sizes. Some art supply places carry copper foil and the like also. On a per ounce basis the brass stuff is expensive, but you can buy a single piece for a few dollars. But as noted above, as long as it's fairly reliable, it is out of sight and good enough is good enough.

Moopheus · Mar 10, 2017

DWThomas said:
Some art supply places carry copper foil and the like also.

I should have thought of that. In fact now that I think of it, I remember that my sister was into jewelry making some years back and I think there is still some scrap metal bits in my mother's garage. Micro-Mark is also a good source for small quantities of random materials.

AgX · Mar 10, 2017

DWThomas said:
Hobby shops catering to model railroaders typically have an assortment of brass pieces (in the US via an outfit called K&S) -- tubes, both round and square, as well as strips in different sizes. Some art supply places carry copper foil and the like also. On a per ounce basis the brass stuff is expensive, but you can buy a single piece for a few dollars. But as noted above, as long as it's fairly reliable, it is out of sight and good enough is good enough.

The main question though is why did manufacturers not make all contacts from stainless steel?

Sometimes the bridging contacts are from stainless steel, but the end contacts then still are both from galvanized brass.
The soldering issue should not had hampered the use of stainless steel.

DWThomas · Mar 11, 2017

AgX said:
The main question though is why did manufacturers not make all contacts from stainless steel?

Sometimes the bridging contacts are from stainless steel, but the end contacts then still are both from galvanized brass.
The soldering issue should not had hampered the use of stainless steel.

Hmm -- in times gone by, I think copper alloys were chosen for conductivity. And in general, brass is easier to work than stainless steel which tends to work harden and be rougher on cutting tools. I also suspect that a decade or three back, stainless was more expensive, although these days brass isn't being given away either! The use of stainless in various parts is now much more common, but I am still not sure it is used much for electrical contacts. And then consumer goods were not manufactured with the idea we'd be using them thirty years later!

AgX · Mar 11, 2017

But a brass contact could be ruined after first use, it does not take 30 years...

Give a battery compartment stainless steel contacts and isolate it to the innards of the camera and one more camera could have been safed.

Moopheus · Mar 11, 2017

I'd guess the fact that brass is a better conductor than stainless had a lot to do with it. If your contact has higher resistance, then you would need to add another battery or a capacitor to the circuit. For a simple instamatic camera like the Spartus, that was not a good choice. This was a $10 camera, so there were limits.

spark · Mar 11, 2017

Moopheus said:
I'd guess the fact that brass is a better conductor than stainless had a lot to do with it. If your contact has higher resistance, then you would need to add another battery or a capacitor to the circuit. For a simple instamatic camera like the Spartus, that was not a good choice. This was a $10 camera, so there were limits.

Hmm, this is DC so we're talking about milliohms of resistance and milliamperes of current, IxR loss difference would be small between brass/bronze and stainless. My guess is that the cost of the stamping and their tooling was a key. Also, not all stainless steels are resistant to battery chemistry.

Clean/Repair corrosion in battery compartment

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