Most batteries contain chemicals that would not harm your exposed skin, however, a leaking battery should be handled with care and precaution. The chemicals in a battery should not be placed near the eyes or ingested. You should consult a doctor immediately if this happens.
Never mix different types of batteries as they have been designed for different uses. For example, mixing a zinc chloride battery with an alkaline battery will lead to a poor performance of your device and can damage the batteries.
Also, do not mix batteries from different brands in a device as that can also lead to damaged batteries and a decreased performance by your device.
The first reported battery was discovered in the late 1930's in Baghdad, called a Parthian Battery which was more than 2000 years old. The battery consisted of a clay jar that was filled with a vinegar solution into which an iron rod surrounded by a copper cylinder was inserted.
Alessandro Volta built the first electric battery in 1798 called the "Voltaic Pile". This early battery consisted of a couple of copper zinc discs separated from one another by cardboard soaked in salt or acid solution.
John Daniell created an improved battery which provided a steadier current in 1836, which was called as the Daniell Cell.
Gaston Plante invented the first rechargeable battery in 1859. This type of battery was lead-acid based and a similar version is still in use today.
Georges Leclanche invented the wet cell in 1868 which was a precursor to the dry cells.
The first commercial dry cell battery was invented in 1888 by Carl Gassner.
1899 saw the invention of the nickel-cadmium battery by Waldner Jungner.
Thomas Edison invented the alkaline battery in 1901 which used iron and nickelic oxide in the cell.
The alkaline-manganese batteries or alkaline batteries was developed by Lew Urry in 1949.
A primary battery is a battery that is designed to be cycled (fully discharged) only once and then discarded. Although primary batteries are often made from the same base materials as secondary (rechargeable) batteries, the design and manufacturing processes are not the same. Primary batteries should not be recharged. Although attempts at recharging a primary battery will occasionally succeed (usually with a diminished capacity), it is more likely that the battery will simply fail to hold any charge, will leak electrolyte onto the battery charger, or will overheat and cause a fire. It is unwise and dangerous to recharge a primary battery.
Do not attempt to recharge primary batteries. This kind of battery is not designed to be recharged and may overheat or leak if recharging is attempted.
Do be careful of the polarity while loading a battery. Reverse polarity may cause damage to the equipment, in which the battery is wrongly loaded.
When recharging secondary batteries, use a charging device that is approved for that type of battery. Using an approved charging device can prevent overcharging or overheating the battery. Many chargers have special circuits built into them for correctly charging specific types of batteries and will not work properly with other types.
Do not use secondary (rechargeable) batteries in smoke detectors. Secondary batteries have a high self-discharge rate. Primary batteries have a much longer shelf life and are much more dependable in emergencies.
Do consult the smoke detector's user manual for the recommended battery types.
Do not attempt to refill or repair a worn-out or damaged battery.
Do not allow direct bodily contact with battery components. Acidic or alkaline electrolyte can cause skin irritation or burns. Electrode materials such as mercury or cadmium are toxic.
Do not lick a 9V battery to see if it is charged. You will, of course, be able to determine whether or not the battery is charged, but such a test may result in a burn that may range from simply uncomfortable to serious.
Do not dispose of batteries in fire. The metallic components of the battery will not burn and the burning electrolyte may splatter, explode, or release toxic fumes.
Batteries may be disposed of, however, in industrial incinerators that are approved for the disposal of batteries.
Do not carry batteries in your pocket. Coins, keys, or other metal objects can short circuit a battery, which can cause extreme heat, acid leakage, or an explosion.
In a device, use only the type of battery that is recommended by the manufacturer of the device.
To find a replacement battery that works with a given device, call the manufacturer of the device or ask the retailer to check the manufacturer's battery cross-reference guide.
Store batteries in a cool, dry place. This helps extend their shelf life. Refrigerators are convenient locations.
Do not store batteries in a freezer. Always let batteries come to room temperature before using them.
Do store batteries in their original boxes or packaging materials. The battery packaging has been designed for maximum shelf life.
When storing battery-powered devices for long periods (i.e., more than a month), remove the batteries. This can prevent damage to the device from possible battery leakage. Also, the batteries can be used for other applications while the batteries are still "fresh."
Use a marking pen to indicate, on the battery casing, the day and year that the battery was purchased. Avoid writing on or near the battery terminals.
Do not mix batteries from different manufacturers in a multi-cell device (e.g., a torch). Small differences in voltage, current, and capacity, between brands, can reduce the average useful life of all the batteries.
When using batteries in a multicell device (e.g., a torch), use batteries of the same age and similar discharged capacity. This kind of matching will make it more likely that all the batteries will discharge at the same rate, putting less stress on any individual battery.
Do not use batteries in high-temperature situations (more than 45°C) unless the battery is designed for that temperature range.
Locate batteries as far away from heat sources as possible. The electrical potential of the battery will degrade rapidly if it is exposed to temperatures higher than those recommended by the manufacturer.
Some batteries may not operate to its optimum level if used below 0°C. In case of doubt check with the manufacturer in such applications.