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Battery Corrosion, Why They Leak And How To Prevent It

June 16, 2015, by Ken Jorgustin


How many of you have encountered a corroded battery compartment in one of your consumer devices? No doubt that most of us have seen the ‘white fluff’ of battery corrosion which has migrated into the battery terminals creating a mess or even ruining the device all-together.

Here is why the battery corrosion happens, how to prevent it, and how to clean it up…

Related: Batteries That Won’t Leak Or Corrode


What is the white fluff corrosion on the battery?


Technically, that white fluffy corrosion that develops at the ends of the battery (most often the negative end) is called potassium carbonate.

All batteries will slowly gradually self-discharge over time. This will occur whether they are setting on the shelf (a much slower process) or installed in a device (which often occurs much quicker) – and dead batteries will eventually leak.

Very high temperatures can also cause batteries to rupture and leak (e.g. in hot car during the summer).

The “alkaline” of the battery is potassium hydroxide (it’s the alkali equivalent of acid’s hydrochloric acid), and this will leak out, forming a white “fluff” of potassium carbonate, typically on the negative end of the battery cell – because apparently the positive end is vented better.


Why do batteries leak?

A reason for battery leaks (e.g. alkaline batteries, AA, etc..) 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. Eventually, the excess pressure either ruptures the insulating seals at the end of the battery, or the outer metal canister, or both.


Why do batteries corrode only if left installed?

While consumer alkaline batteries (such as the AA battery shown above) can leak and corrode while on the shelf (although less likely), batteries that are left installed in devices will gradually self-discharge or discharge because of small trickle current drains put on the battery (sometimes called ‘parasitic drain’). This leads to a dead battery (or batteries) which will out-gas and corrode.

Many devices have a parasitic drain which slowly discharge batteries. When the device is left unattended for long periods of time (with the batteries installed) the drain will slowly kill the batteries (which will then leak). Examples of this drain (even when the device is turned off) might be a clock display (display screen) on a portable radio, or a ‘find me’ dimly lit LED (for example). Many modern devices have active circuitry which is always ‘on’ to some extent and slowly draining the batteries while you may not even realize it.


How to prevent battery corrosion

By simply removing the batteries from devices that will not be used for some time, will prevent a slow discharge of the batteries, and therefore prevent leakage because you are preventing ‘dead batteries’. Dead batteries are more likely to leak.

Keep them in a battery case such as this one…
AA Battery Caddy, Holds 12 Batteries

If you have a portable radio (for example) and it’s set aside for emergencies – or if you don’t plan to use it for months – then you should remove the batteries from the battery compartment to prevent a potential slow discharge and the resulting leak and corrosion.

The device shown in the photos above is one of those closet LED lights which automatically turn on when it senses motion. I keep several of them in a few hard-to-reach cupboard spaces in my camping trailer so I can see what’s in there more easily. I had forgotten to remove the batteries last year and since the device is always ‘on’ while ‘sensing’ for motion, the slow parasitic drain killed the batteries and they subsequently leaked.


How to clean battery corrosion

Use vinegar or lemon juice to clean up the corrosion ‘fluff’ caused by leaking ‘alkaline type’ batteries.

Note: regarding batteries with an acid makeup (e.g. car batteries), you can clean up battery corrosion by mixing a solution of baking soda and water to make a sort of paste solution which will neutralize the acidic corrosion of the battery terminals.


So for all you preparedness-minded people who are storing battery-operated devices for a ‘rainy day’, be sure to remove those batteries before they corrode your battery compartment…

Speaking of batteries, here is one of the best rechargeable batteries out there (I use lots of them around here)… Panasonic ‘eneloop’ rechargeable battery

Here’s a little more about them –