All of us now have Smart Phones, Portable Media Players, Digital Cameras, Tablets and Wearables and what is common about them is that they all carry a battery. However, not many know about the pros and cons of batteries used in these Wireless Devices and the technology behind it. Battery form factors can be proprietary, as with most mobile phone, two-way radios, barcode scanners laptop computers, or standard, as with most flashlights, cameras. Batteries also differ in the chemistries that make them work; the three most common battery chemistries are NiCd, NiMH and Li-Ion. A vast majority of the wireless devices that sells come standard with rechargeable batteries.

Nickel-Metal Hydride or NiMH batteries can offer superior operation life between charges, they offer a higher capacity which results in longer run time when compared to NiCd batteries. This battery chemistry provides 30-40% longer operation time than NiCd but does not operate as efficiently in extreme temperatures. However, NiMH is less susceptible to "memory effect" compared to NiCd batteries. They are nearly twice as heavy as NiCd batteries. They also don't have a memory effect. They are a good medium temperature battery. You can operate with them usually in -5 to 95 degrees farenheit with no adverse problems. They have good deep-discharge qualities and can store nearly twice the capacity of NiCd cells. Their life-cycle is generally lower than NiCd, at 500-800 life cycles.

Nickel Cadmium or NiCd batteries are the oldest chemistry and known for their robustness. They are good for working in extreme temperatures. NiCd batteries are currently one of the most cost-effective chemistries on the market. NiCd batteries give you more watt-hours of operation per shift than other battery chemistries. NiCd battery's major drawback, they have a charging problem called the "memory effect". That is, they don't get completely charged after each use, or its propensity to "forget" and not utilize its full capacity. This can shorten the lifespan of the battery which can be a serious tradeoff. They can be reconditioned but at the cost of at least 3 life cycles. 

Lithium Ion and Lithium Polymer batteries are known for their enormous energy density, the power to weight ratio, which easily exceeds that of NiMH for a lighter, smaller power supply. They are able to store more energy per pound than any of the traditional battery packs. These batteries tend to be the industry's most expensive chemistry, and they offer a major advantage of not experiencing "memory effect". Environmentally they are safer to dispose of than NiCd. However, Li-Ion is not good for extreme temperatures. Lithium-ion batteries can be a safety hazard since they contain a flammable electrolyte and may become pressurized if they become damaged. A battery cell charged too quickly could cause a short circuit, leading to explosions and fires. Because of these risks, testing standards are more stringent than those for acid-electrolyte batteries, requiring both a broader range of test conditions and additional battery-specific tests, and there are shipping limitations imposed by safety regulators, like IATA.

Other than the above mention chemistries, here are some other form of batteries which are worth mentioning:

• Lead-acid batteries are heavy, often contain concentrated liquid acid, are capable of delivering high voltages, and will endure many charge-discharge cycles. The most common application of lead-acid batteries is in gas-powered engines.

• Zinc-carbon batteries are the “standard” variety that is now less common, now that alkalines are readily available. Zn-C batteries come in standard AA, AAA, C and D sizes and are usually cheaper than alkalines. They have less capacity than a comparable alkaline, and they have a propensity to leak and corrode over time, sometimes taking the device they’re in with them.

• Alkaline batteries, the most common type sold in stores in size AA, AAA, C and so on, are usually Alkaline Manganese Dioxide. Historically, alkaline batteries were not rechargeable, but a relatively new formulation called Rechargeable Alkaline Manganese (RAM) allows alkaline cells to be recharged and does not have a memory effect. Do not assume an alkaline battery is a RAM formulation unless the label specifically indicates this. Recharging a standard alkaline battery can cause it to explode.

• Zinc Air batteries are usually in “button” or “coin” form factors, common to hearing aids and wristwatches. They have an extremely long shelf life, losing only about 2% of their capacity per year, and supply a lot of power for their size. They usually have a paper seal that, once removed, causes the battery to discharge fairly quickly. It’s technically possible to recharge these, but for most applications, it’s not worth the trouble.