The 9 Best 9V Batteries

For a test meter, a wireless mic or a sensor that lives outdoors, the Energizer Ultimate Lithium is the pick. Energizer rates it for ten years on the shelf and for work from deep winter cold to desert heat, and lithium cells are much less likely to leak and ruin a device. Electronics hobbyists on the EEVblog forum favor it for their meters. It's pricey for each cell, and its life in smoke alarms varies more than you'd expect.

Most smoke alarms are built around a plain alkaline cell, and the Duracell Coppertop is a safe, well-documented choice for them. Duracell publishes a full technical sheet for this cell, which few battery brands bother to do, and it guarantees the battery for five years in storage. A fresh one commonly runs a home alarm for a full year before the low-battery chirp. Bought in pairs, though, each cell costs a good deal more than in a bulk box.

When the hallway alarm starts chirping and you just need a fresh pair, the Energizer MAX does the job for very little money. It's an ordinary alkaline cell that Energizer says keeps its charge for up to five years in a drawer, and the maker now uses some recycled material in it. Like any alkaline, it weakens in the cold and can leak if it's left in a dead toy or gadget for months.

The Amazon Basics Lithium four-pack is the cheap way to put long-lasting cells in every alarm, meter and outdoor sensor at once. Each one is rated for up to ten years in storage and for use in freezing garages and hot attics alike. It's a store brand without a detailed technical sheet, and results vary: some cells run well past a year in a smoke alarm, while others give out within a few months.

A house full of smoke alarms, remotes and toys is cheapest to keep running with the Amazon Basics Alkaline twelve-pack. These are standard alkaline cells rated for five years in storage, and the box keeps spares from rattling against each other, which matters with terminals that can short. Amazon doesn't publish a detailed technical sheet, so you're trusting a store brand's quality control. Write the purchase date on the box when it arrives.

Landlords, electricians and anyone who swaps a dozen alarms at a time are who the Duracell Procell Constant is made for. It's Duracell's line for professional buyers, packed loose in a plain box with no blister packs to cut open, and it's meant for low-drain gear such as alarms, clocks and remotes. Stock of this box runs thin, and loose cells need a safe spot so their terminals don't touch metal.

Lithium in a pair suits anyone with one or two alarms to fill, and the Tenergy Lithium gives you that without a bigger pack. Tenergy claims it keeps nearly all its charge across a decade in storage. Each cell carries a printed warning not to charge it, a useful reminder from a brand best known for rechargeables. Its cold rating stops a little below zero Fahrenheit, so skip it for an unheated winter cabin.

Spares for the emergency drawer should last, and the ACDelco Super Alkaline eight-pack carries a seven-year storage promise, longer than most alkaline cells get. The name is licensed: Powermax, a battery company, makes these, not the car-parts brand. They're a cheap way to keep fresh cells on hand for alarms, remotes and radios. There's no public technical sheet, though, and independent data on how long they run is scarce.

Guitarists with a pedal board and anyone who drains meter batteries fast can cut waste with the HW USB-C Rechargeable set. Each cell has its own charging port, a split cable charges all four at once, and a small light turns on while it charges. The maker claims up to a thousand charges. Because the voltage stays steady until the cell is nearly empty, a device gets little warning before it stops, so keep these out of smoke alarms.