Answers to Your Questions About 9-Volt Batteries

Nine-volt batteries are some of the most common batteries used in everyday households. We get a lot of questions about 9V batteries, and today we’re giving you the answers! Here’s what you need to know about 9V batteries. 

What Are 9-Volt Batteries Used For

A wide range of household devices and appliances require 9V batteries. They are perhaps most widely used in smoke detectors, but are also commonly used in remote control devices and toys, multimeters, home massagers, certain battery-powered microphones, radios and musical instruments including guitars. 9V batteries are generally better suited to devices that require a stronger battery with higher capacity than a typical AA or AAA battery can provide. 

What’s Inside a 9-Volt Battery

Ever wonder what you would find inside a 9V battery? Nine-volt batteries are actually true batteries, in the sense that they contain a series of individual battery cells. This sets them apart from AA, AAA, C and D batteries, which are all single cells and would more accurately be called “battery cells” and not true batteries. 

A typical 9-Volt battery actually contains six AAAA cells (that’s right, quadruple-A!) which are bundled together and connected in a series. Each AAAA cell is 1.5 volts, and all six add up to 9 volts. 

Are All 9-Volt Batteries the Same

All 9V batteries are definitely not the same! Just like other sizes and types of battery, there’s a lot of variation in the composition of 9V batteries, and thus a lot of variation in battery capacity, power and usage. 

In reality, not all 9V batteries are necessarily the same size. That being said, the batteries we all think of when we think of 9V batteries are the small, rectangular batteries with positive and negative poles side by side on the top. This common size is technically known as a PP3 battery, but most folks just call it a 9-volt battery. 

The most widely used 9V batteries are primary batteries, otherwise known as single-use or “disposable” batteries. Within that broad category, alkaline batteries are the most common, including many of the most popular 9V batteries sold by top brands like Duracell 9V CopperTop Batteries

Lithium is also an option for primary 9V batteries, with Energizer L522 9V Ultimate Lithium being an excellent choice. In recent times, rechargeable options including nickel-cadmium (NiCd), nickel-metal hydride (NiMH) and lithium-ion batteries have also been introduced and gained much popularity. 

Can You Recharge a 9-Volt Battery

Only certain 9V batteries can be recharged. The most common rechargeable 9V batteries are nickel-metal hydride (NiMH) batteries, which can be recharged and reused hundreds of times with the proper charger. 

Many of the most common rechargeable 9V-size NiMH batteries are not precisely 9-volt. Powerex Precharged NiMH batteries, for example, come in 8.4-Volt and 9.6-Volt variations, both of which are the same industry standard size as any PP3 9V battery. 

Lithium-ion 9V batteries are also rechargeable, but you cannot recharge alkaline 9V batteries and other types of primary battery that were not designed to be recharged. Doing so can destroy the battery and potentially damage your charger or any device you put the batteries in. 

How Long Does a 9-Volt Battery Last

How long a 9V battery will last depends on a wide range of factors, including what type of device you use it in. High-drain devices like toys and guitar pedals will drain a 9V battery much more quickly than low-drain devices like smoke detectors. 

Different types of 9V batteries also have vastly different lifespans. A 9V alkaline battery will typically last 1-2 years in a smoke detector, whereas a 9V lithium battery may last as long as 5 years. 

A good way to get a sense of how long a battery will last is to locate the mAh (milliampere-hour) rating on the packaging. This rating essentially measures the amount of electrical charge a battery can store, and a higher number means a battery will last longer. 

A typical 9V alkaline battery has a capacity of 550 mAh, compared to a typical 9V lithium battery, which has a capacity of 1200 mAh. Rechargeable NiMH 9V batteries are usually around 250 mAh, while rechargeable lithium-ion 9V batteries are about 650 mAh. This number is less important in batteries that can be recharged over and over again, but still worth considering. 

Are 9-Volt Batteries Safe

9-Volt batteries are perfectly safe as long as they are used and stored properly. Because PP3 batteries have both their positive poles next to each other rather than at opposite ends, some care must be taken to avoid the poles of two batteries coming into contact with each other or another metal object, which can cause them to short and spark, potentially creating a fire hazard. 

For this reason, it is recommended that 9V batteries be stored in their original packaging. Don’t let unpackaged batteries tumble around loose inside a bag, container or drawer. If you do have 9V batteries that are loose and not fully empty, use a protective cover or a piece of tape to cover the poles. 

How Do You Dispose of a 9-Volt Battery

Some states allow alkaline 9V batteries and other batteries to be disposed of in your regular trash, and others do not. In many cases, you may be able to take used batteries to a collection site for hazardous household waste. Check the regulations in your city or state. 

Lithium and rechargeable batteries should never be disposed of in your trash or recycling bin, but they can be recycled by taking them back to any retailer that sells them. In most states, retailers that sell rechargeable batteries are also required to offer collection of them for recycling. 

However you choose to dispose of your 9V batteries, be sure to cover the poles with a piece of tape first. 9V batteries usually still have a small amount of charge left even if they are nearly dead, and it may be enough to start a fire if the poles come into contact with metal.