Why Do Batteries Leak?
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…
(See below for car batteries / corrosion)
Update Note (2018), Energizer guarantees that these particular batteries will NOT corrode. I made the switch from other brands and can attest that none of them have leaked:
What is the white fluff corrosion on the battery?
Technically, the 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.
High temperatures can also cause batteries to rupture and leak (hot, summer environment).
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 if left installed?
While consumer alkaline batteries (such as the AA battery shown above) can leak and corrode while on the shelf, more likely are batteries that are left installed in devices.
These batteries will gradually and naturally self-discharge, or discharge even quicker 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 are always ‘on’ to some extent and slowly draining the batteries while you may not even realize it.
How to prevent battery corrosion
Simply remove the batteries from devices that will not be used for some time.
This will prevent a slow discharge of the batteries and therefore prevent leakage when the batteries get low or go dead. Dead or low batteries are more likely to leak.
Use a battery storage case:
Example: You might have a portable radio set aside for emergencies. Or maybe you haven’t used it for months and months. You should remove the batteries from the battery compartment to prevent a potential slow discharge and the resulting leak and corrosion.
How to clean battery corrosion
To clean up the corrosion ‘fluff’ caused by leaking alkaline batteries:
– Vinegar or Lemon juice.
– Soak and swab a Q-tip over the terminals.
Batteries with an acid makeup (e.g. car batteries), how to clean up battery corrosion:
– Mix a solution of baking soda and water to make a sort of paste solution.
– This will neutralize the acidic corrosion of the battery terminals.
For Car Batteries (lead acid),