Alkaline battery leaks- how to restore corroded terminals?

This has happened on my Celestron 4" astronomical telescope, not a light-generating but rather a light-gathering device, if you will, and more expensive than any flashlight I ever hope to own. I hadn't had the thing out of the closet for quite a while and then, glimpsing its case on the shelf, had an awful feeling (call it a loving father's instinct)- and sure enough, two of the four alkaline AAs on the motor drive had leaked, corroding and blackening the terminals [if perchance you don't know, the motor drive in the base of such a scope turns it and keeps the scope focused on the same spot in the sky, otherwise the view moves as the earth turns, making the motor drive VERY handy). Normally, with alkaline batteries, I clean the corrosion off and swab with vinegar (the anti-alkaline!) to stop further damage, then polish the damaged metal and test. But I haven't tested the 'scope with new batteries because I'm afraid I won't like the result... or the hundred dollar repair job. Does anyone have any advanced tips on repairing such battery terminal damage?

There's no magic. You have to wash away any wet electrolyte and soft deposits using damp swabs or by rinsing under a tap if you can disassemble the battery compartment and separate it from the rest of the device. Then you have to clean away any hardened corrosion using swabs soaked in vinegar, or stronger stuff (I recently used CLR calcium lime rust remover). Make sure to do a final rinse with distilled water. Finally you have to repair any corrosion damage to the underlying metal if needs be. If the corrosion was bad you might consider touching up the surface of the springs with some solder to restore a shiny contact surface.

If the leak was extensive you should disassemble the battery compartment to look for any damage beyond or out of sight.

Lastly, start using eneloops instead of alkaline batteries.

Good advice all round Mr Happy. What worries me is that in the past I've had blackened terminals (in headlamps, actually) that no amount of anything could induce to carry a current again. That's what I'm afraid of here. The eneloops suggestion is of course very good under the circs- the commitment of that brand of batteries to something I only use rarely these days wouldn't have seemed worth it before this happened, but now strikes me as a great idea.

I once thought about replating contacts that were damaged by battery leakage but found the initial investment cost was prohibitive. Like Mr. Happy said you just have to work it out cleaning and polishing them till they work properly. If you can somehow take things apart and find a way to replace damaged parts that would be great but I find the wide variety of contacts and springs used make it nearly impossible to find a match when it comes to replacement parts. One thing you can do after the repair is to use some sort of coating agent on the contacts which could protect it some from further leaks but IMO anything that is rather expensive you should consider lithium primaries or nimh instead of alkaline as even if the risk of leakage is small the damage resulting offsets the cost of leak resistant batteries.

Mr Bigglow said:

What worries me is that in the past I've had blackened terminals (in headlamps, actually) that no amount of anything could induce to carry a current again. That's what I'm afraid of here.

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Not even sandpaper?

I recall using sandpaper, then a special fibreglass-bristled contact cleaning brush (Radioshack), then a rather coarse lapping grit polish compound. That was on a Petzl headlamp, as I discovered, no doubt after throwihg it against the wall a couple times, the terminals unit popped out of the battery box and the store was kind enough to replace them from parts they had.

Anyway, barring the magic suggestion I'm hoping for, sooner or later I'll have to man up and try the darn scope as-is....

Mr Happy said:

What worries me is that in the past I've had blackened terminals (in headlamps, actually) that no amount of anything could induce to carry a current again.

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That's why I used CLR. Vinegar isn't strong enough to remove hardened corrosion. Clean down to bare metal, tin the surface with solder if necessary, and it will conduct.

But if corrosion gets beyond the battery compartment it could destroy other things, and then the device will not work no matter how clean the battery springs are.

One suggestion is to install another battery holder and wire it into the electrical circuit thus replacing the damaged holder. This would have to fit in the allotted space.

I found very useful suggestions in the last two posts, thanks Guys. I'm up to tinning and also rewiring and in fact there's a fair amt of space available to install a new battery holder. To The Stars!