tomcat

Hope this answers everyone's questions about alkaline batteries. I copied it straight from Wikipedia, so I take 0 credit for its accuracy:

Alkaline batteries are prone to leaking potassium hydroxide, a caustic agent that can cause respiratory, eye and skin irritation. Risk of this can be reduced by not attempting to recharge disposable alkaline cells, not mixing different battery types in the same device, replacing all of the batteries at the same time, storing in a dry place and at room temperature, and removing batteries for storage of devices.

All batteries gradually self-discharge (whether installed in a device or not) and dead batteries will eventually leak. Extremely high temperatures can also cause batteries to rupture and leak (such as in a car during summer) as well as decrease the shell life of the battery.

The reason for leaks is that as batteries discharge — either through usage or gradual self-discharge — the chemistry of the cells changes and some hydrogen gas is generated. This out-gassing increases pressure in the battery. Eventually, the excess pressure either ruptures the insulating seals at the end of the battery, or the outer metal canister, or both. In addition, as the battery ages, its steel outer canister may gradually corrode or rust, which can further contribute to containment failure.

Once a leak has formed due to corrosion of the outer steel shell, potassium hydroxide absorbs carbon dioxide from the air to form a feathery crystalline structure of potassium carbonate that grows and spreads out from the battery over time, following along metal electrodes to circuit boards where it commences oxidation of copper tracks and other components, leading to permanent circuitry damage.

The leaking crystalline growths can also emerge from seams around battery covers to form a furry coating outside the device, that corrodes any objects in contact with the leaking device.

SteveR Loc: Michigan

Left batteries in the flash too long? Don't forget the right ones, too.

blackest Loc: Ireland

It is unfortunately common for battery powered devices to still take a tiny amount of current even when off which eventually will flatten the battery, slow but much faster than just being stored. One option might be to use a piece of plastic between one of the battery terminals and the battery connector. It's fairly common for things to arrive with batteries installed and there be a plastic tab to remove. Batteries will still discharge some but not so fast and maybe stay just above critical levels. Sometimes a device may get turned on in a bag and completely discharge in a couple of days, so its worth considering.

wj cody Loc: springfield illinois

q tips and CLR, it's what we use all the time. just use a little and clean thoroughly. if that doesn't work, into the waste basket!

JCam Loc: MD Eastern Shore

First, I didn't suggest 5%! Borrow the box of Baking Soda from the "Lord of the Kitchen" and mix your own solution. If you really want to, you could even mix a paste (normally for auto type batteries). The idea is to neutralize the acid with the base; 7.0 ph is neutral, but you don't have to be that precise--just treat then clean and repeat. When there is no longer a reaction (bubbling) the acid is neutralized; then, clean well with water (maybe using 'Q tips'). If, as the OP said, the batteries my have been leaking for a long time, the acid may have made its way into the circuits, and the flash is 'toast', but it's worth a try.

tomcat

tomcat

There's no acid in alkaline batteries. See the earlier Wikipedia post. It's potassium hydroxide, a base, that is leaking so baking soda won't neutralize the white crud. Sorry

JCam Loc: MD Eastern Shore

OK, I'm not a Chemist & haven't taken any Chemistry classes for over 50 years; back then there were no alkaline batteries! To be factually correct, there is NO ACID in carbon-zinc batteries either; it is the chemical reaction between the C & Zn that makes the acid. If I recall properly, the OP just said "batteries" and no type so an assumption that they were carbon-zincs is logical and was made by most respondents.

tomcat

That's ok. No harm no foul. I'm assuming the OP had to be talking about alkaline because I don't ever see C-Zn batteries for sale nowadays

BHC Loc: Strawberry Valley, JF, USA

So why would you clean alkaline corrosion with an alkaline solution?

rook2c4 Loc: Philadelphia, PA USA

Right. Electrical engineers have been using WD40 for decades to clean electrical contacts. Not good to clean lubricated moving parts (such as shutter blades), but okay for contacts. The key is to use only a very small amount of WD40 on the swab so that none of it will drip into the camera.

wj cody Loc: springfield illinois

i would be very wary of doing that. while it is popular, it is not advisable as the wd40 leaves a film on the contacts. again, clr would be the most appropriate as i noted above.

TriX Loc: Raleigh, NC

Maybe, but I've never seen a tech or a EE use regular WD40 on any contacts in my 50+ years in electronics (not to say it hasn't happened - just haven't ever seen it). Now there are contact cleaners with a conductive lubricant (for potentiometers), and WD40 actually makes a seperate contact cleaner/lubricant. Wonder why they make a special product If regular WD40 works? Personally, I would never put WD40 on anything camera-related. Car battery terminals - maybe, but it wouldn't be my first choice.

tomcat

Correct. That was my reason for the post so folks would use diluted vinegar. That's what I use, with a q-tip