A hot battery could have several causes: from wrong storage to short circuiting. Some warmth is okay but keep an eye out for unusual heat.

The revised RoHS (Reduction of Hazardous Substances) Directive 2011/65/EU...

Typically for an alkaline battery is a gradually decreasing voltage when it discharges, which means that for some appliances, which need a high base voltage to operate, the appliance stops working even while the battery has still a bit of energy left.

Turn off the device and remove the battery immediately. Remove the remaining leakage using a cotton swab. Avoid skin contact at all times.

This should be avoided at any time. When the battery has been in a washing machine, it is no longer fit to use. Please dispose of this battery.

In case of skin contact there is a chance of chemical burns. Use clear tepid water for at least 15 minutes on exposed skin. Consult a physician in case of irritation, injury or pain. In case of contact with the eye, do not rub the eyes, but flush with clear tepid water for at least 30 minutes.

Due to chemical reactions inside most batteries, the stored charge of the batteries is reduced little by little. This phenomenon is called self-discharge.

Please store your batteries in dry conditions, and avoid high temperatures and direct sunlight.

Make sure you measure the correct way: connect the poles to their corresponding measuring ends.

Use batteries for their right purpose: insert them correctly, replace them when empty and store them high and dry.