Advantages and Disadvantages of Rechargeable Batteries

Advances in energy storage technology have led to growth in the popularity and utility of rechargeable batteries. However, renewable batteries have their limitations, and for some applications single-use batteries still have the edge. When you need to select a battery type, it's helpful to understand the advantages and disadvantages of each so that you make an appropriate choice.

The Technology: Types of Batteries

For some applications, functional requirements make rechargeable batteries the only practical choice. The most obvious example is the car battery, which is in a constant state of recharging. Whether or not to use rechargeable batteries is mainly an issue for small devices powered by AAA, AA, C and D batteries. Prior to 2000, nickel-cadmium or NiCd batteries were the primary rechargeable type. The main rechargeable technology now sold is nickel-metal hydride, or NiMH. Non-renewable alkaline batteries usually rely on a chemical reaction between zinc, magnesium oxide and potassium hydroxide. This reaction is not reversible. By contrast, passing an electric current passed through a NiCd or NiMH battery will reverse the chemical changes and re-energize the battery.

Technical Advantages and Disadvantages

The fact that rechargeable batteries can be re-energized and reused is a major advantage. NiMH batteries can be recharged 150 to 500 times. You must dispose of non-rechargeable batteries and purchase more when they are depleted. Rechargeable batteries are also recyclable. Between this and their reusability, using rechargeables means far fewer of these chemical devices find their way to landfills where they may contaminate the environment. The main disadvantage of NiMH batteries, though, is a short shelf life. NiMH batteries must be recharged every month or two even when not in use, while single-use alkaline batteries that are not in use will hold a charge for five to seven years. One reason that older NiCd rechargeable batteries have lost favor is that they must be drained completely or they will not fully recharge. NiMH batteries don't share this disadvantage.

Practical Considerations

A major plus for rechargeable batteries is cost. They are more expensive to purchase; however, they have a far better cost-performance ratio because they can be re-energized hundreds of times at a cost of a few cents per charge. Single-use alkaline batteries still have a place, largely because of their long shelf life. They are ideal for applications that are low-demand or low-drain in nature. For example, a flashlight kept for emergencies should have a single-use battery so that it will function when needed. Low-drain applications include wall clocks and remote control devices. Rechargeable batteries are better for frequently used consumer electronics and maintain their power level as they discharge, which alkaline batteries do not. This can be an advantage in the short-term, but it also means a rechargeable battery may stop working with little warning.

The Bottom Line

Rechargeable batteries have a long-term cost advantage that will likely make them a major player among battery sales for the foreseeable future. However, non-renewable batteries offer long a long shelf life that is particularly useful for low-demand and low-drain functions. This is subject to change; energy storage technology of all kinds is a major research topic for industry and the government, which could upend current usage. It is entirely possible that a rechargeable battery technology that offers a long shelf life will emerge at some point.