If you’ve put away a device and forgotten to take out the batteries, the terminals are probably covered in battery acid by now. The good news is, you can clean them pretty easily, depending on the severity of the leak.
Alkaline batteries—the kind you use to power clocks, TV remotes, flashlights, children’s toys, and so on—are made of a cathode (manganese dioxide) and an anode (zinc). These react to one another and produce the electrons, which, with the help of an electrolyte (potassium hydroxide), power your gadgets.
When alkaline batteries completely discharge (which happens long after they stop providing adequate juice to your devices), the potassium hydroxide breaks down. This process produces hydrogen gas and builds up pressure inside the battery. Eventually, this ruptures the steel casing, and potassium hydroxide leaks out in the battery compartment and, sometimes, over the circuitry inside the device.
It can take years for this to happen or just a few months, depending on the quality of the battery and how much parasitic draw (the power a device uses while it’s turned off) the item has.
This is why it’s always important to remove the batteries before you stow away gadgets.news react node