Rechargeable batteries are advertised as being able to be reused more than 500 times, greatly reducing the cost of replacing the batteries. Some forms of rechargeable batteries will be more expensive than standard batteries, and the first-time cost of the charger itself must be taken into account. However, using the batteries repeatedly can save up to hundreds of dollars a year.
At one time, rechargeable batteries were believed to have a much lower performance than the standard alkaline batteries. However, technology has improved in this area, to the point where some rechargeable batteries are actually advertised to have a higher performance than normal batteries. Nickel-cadmium batteries have been known to perform well in very cold conditions and when excessively used, reducing the amount of times one would need to charge them.
Rechargeable batteries can be a hassle to recharge, especially if that forces any devices to be powerless while their batteries wait to recharge. Also, many such batteries have a high self-discharge rate, meaning they often need to be charged after just being stored. A second emergency set of batteries can solve the first problem, but the latter just complicates that solution.
Certain types of batteries, depending on their composition, are useful only with certain devices. Older hand-held devices will warn against using nickel-based batteries in them and recommend alkalines instead. Due to the cost of their materials, lithium ion batteries are used mainly in computers and cameras. The high number of different compositions can make it confusing for someone to decide which battery is best.
Some rechargeable batteries, especially the nickel-cadmium variety, contain chemicals even more dangerous than those inside alkaline batteries. This makes them a very high environmental risk and one of the main reasons some countries place restrictions on the number of nickel-cadmium batteries that can be used.