Alkaline Batteries – FYI

Anyone using alkaline batteries will eventually encounter a corroded battery.  Since battery-corrosion is not covered in most warranties, what should a consumer know?  Why does battery corrosion happen? Can it be prevented? Is there a way to clean it up and salvage my flashlight (or other device)?

What is the corrosion on the battery?

Technically, the white fluffy corrosion that develops is called potassium carbonate. The “alkaline” of the battery is potassium hydroxide (the alkali equivalent of hydrochloric acid). It’s not exactly “acid”, but it can cause skin irritation and severe irritation of the gastro-intestinal tract with nausea, vomiting and burns, if ingested. So, care should be taken when addressing and clean-up should be completed.

Why do batteries leak?

One reason batteries leak is that as batteries discharge, the chemistry of the battery changes and some hydrogen gas is generated. This “out-gassing” process increases pressure in the battery and eventually causes rupture(s) within the insulating seals or the outer metal canister (or both). Another reason is that very high temperatures and/or major changes in temperature can also cause batteries to rupture and leak (e.g. leaving in hot car during the summer). However, all batteries will gradually self-discharge over time and this will occur whether they are setting on the shelf (slower process) or installed in a device (usually much quicker). When “dead”, all alkaline batteries will eventually leak.

While consumer alkaline batteries can leak and corrode while on the shelf, batteries that are left installed in devices will gradually self-discharge faster due to a “small trickle” of current draining on the battery. (Many devices have a “parasitic drain”, due to active circuitry, which slowly discharges batteries when the device is left unattended for long periods of time, slowly draining the batteries while you may not even realize it.)

How to prevent battery corrosion

Preventing battery corrosion can be difficult. Battery cells (the battery before being branded and wrapped with the outer cover) come from large, non-climate controlled warehouses where they been in storage for a while. This means they are not usually stored at a constant temperature or humidity level and it’s already difficult to know how much draining or off-gassing has taken place.

  • Simply removing batteries from devices that will not be used for some time, will help prevent a slow discharge of the batteries, and therefore prevent leakage. (Such batteries should be stored in a simple “side-by-side” plastic case, that prevents positive and negative ends from touching.)
  • Establishing a schedule of “rotation and replacement” is also helpful. (If you leave a flashlight in your car or truck, have an established calendar schedule or a monthly cell-phone reminder to check your batteries, swap them around in your light and replace them at proper intervals.)

How to clean battery corrosion

You can use simple vinegar, lemon juice or a mixture of baking soda and water to make a sort of paste solution to clean up the corrosion and wipe it clean. You can also use a pencil eraser to help in the cleaning. – Note: If you successfully clean up your flashlight and place new batteries, you may need to add just a bit of spit/saliva to the end(s) of the battery(s) to regain a contact with the cleaned contacts.