Battery Sizes Explained: AA, AAA, C, D, 9V and When Rechargeables Win
Posted by EMILY T.
Updated August 2026
Every junk drawer in America contains batteries that fit nothing in the house. The sizes look similar, the packaging all promises long life, and the chemistry names, alkaline, lithium, NiMH, sound interchangeable when they are not. This guide sorts out the five household sizes, which devices take which, what the chemistry differences actually mean, and when rechargeables beat disposables. It ends with the case for buying in bulk, since that is what we sell: brand-new, factory-sealed Energizer and Duracell batteries at below-retail prices.
The five household sizes
Household batteries are standardized, so any brand's AA fits any device that takes AA. The sizes differ in physical dimensions and in how much energy they hold: the bigger the cell, the more energy it stores, at the same voltage for AA, AAA, C, and D.
| Size | Shape | Typical voltage | Common devices |
|---|---|---|---|
| AAA | Slim cylinder | 1.5V | TV remotes, thermometers, small flashlights, thermostats |
| AA | Standard cylinder | 1.5V | Toys, wireless mice and keyboards, clocks, flashlights, game controllers |
| C | Wide, medium-height cylinder | 1.5V | Larger flashlights, portable radios, some toys |
| D | Widest, tallest cylinder | 1.5V | Lanterns, big flashlights, emergency radios, some paper towel dispensers |
| 9V | Rectangular with two top snaps | 9V | Smoke detectors, multimeters, some wireless microphones |
A few practical notes. AA and AAA cover the overwhelming majority of household devices, which is why they sell in the biggest packs. C and D cells are physically larger versions of the same idea, used where a device needs to run a long time or push more current. The 9V is the odd one out, a higher-voltage rectangular battery whose most important job in most homes is the smoke detector. Never guess between C and D, or between AA and AAA, by eye alone if you are unsure: check the marking molded into the device's battery compartment, which nearly always states the size.
Alkaline, lithium, NiMH: what the chemistry means
Size is the fit; chemistry is the behavior. Three chemistries matter for household sizes.
Alkaline is the standard disposable chemistry, what most people mean by "a battery." Energizer Max and Duracell Coppertop are alkaline lines. Alkalines are inexpensive, hold their charge in storage for years, and suit almost every household device. Their weaknesses: performance drops in freezing temperatures, voltage sags as they drain, and a fully dead alkaline left in a device for a long time can leak. The packaging states the shelf life, and modern alkalines from major brands store for many years.
Lithium disposables, such as Energizer Ultimate Lithium in AA and AAA, are premium single-use cells. They are lighter than alkalines, perform far better in cold, hold very long shelf lives, and resist leaking. They cost more per battery, which is why they make sense in specific places: outdoor gear, trail cameras, smoke detectors where the manufacturer permits them, emergency kits, and anything that lives in a car through winter. Check your device's manual first, since a small number of devices specify alkaline only.
NiMH rechargeables, such as Energizer Recharge and Duracell Rechargeable, are the household rechargeable chemistry in AA and AAA. They run at a slightly lower nominal voltage, 1.2V instead of 1.5V, which the vast majority of devices handle without issue. They can be recharged hundreds of times, which transforms the economics for any device that eats batteries.
When rechargeables win, and when they do not
The math is simple: a NiMH battery costs more upfront plus a charger, then costs almost nothing per use afterward. So rechargeables win wherever batteries drain quickly and get replaced often. Game controllers, wireless keyboards and mice, kids' toys, camera flashes, and frequently used flashlights are the classic cases. A household with two game controllers and a few battery-hungry toys can burn through dozens of alkalines a year; two sets of NiMH cells rotating through a charger replace all of them.
Disposables win in the opposite situations. Devices that sip power over years, like remotes, clocks, and thermometers, drain a battery so slowly that recharging never pays off, and alkaline's long storage life is the better fit. Emergency gear favors disposables too: NiMH cells self-discharge over months, while an alkaline or lithium disposable in a flashlight or radio will still be ready after sitting for years. And smoke detectors should use exactly the battery type the detector's manufacturer specifies, replaced on the schedule they specify, with no substitutions to save money.
Most households land on a mix: NiMH for the handful of high-drain devices, alkaline in bulk for everything else, and a few lithiums in the emergency kit and the car.
Why bulk buying makes sense
Batteries are the definition of a product worth buying in bulk. Every household uses them continuously, they store for years, and the per-battery price drops meaningfully in larger packs. The reason people do not buy in bulk is usually sticker price at the register, which is where liquidation pricing changes the picture.
Our Energizer and Duracell stock is surplus and overstock inventory, brand new and factory sealed, priced below standard retail. Same batteries, same sealed retail packaging, lower price. Where a product has a date printed on the packaging, our listing states it, phrased as best-before, so you can see exactly how much storage life you are buying. Store batteries in a cool, dry place at room temperature, in their packaging, and away from metal objects that could short the terminals, and they will be ready when a device needs them.
Frequently asked questions
Do brand-name batteries actually last longer than off-brand?
Major-brand alkalines from Energizer and Duracell are consistent in capacity, shelf life, and leak resistance, which is what you are paying for. Off-brand cells vary widely, and the cheap ones tend to be worst at exactly the things that matter: holding charge in storage and not leaking in a device. Since we sell the major brands below retail, the price argument for off-brand mostly disappears.
Can I use rechargeable batteries in everything?
Nearly everything that takes AA or AAA will run on NiMH despite the slightly lower 1.2V nominal voltage. The exceptions are devices whose manuals specify disposables, and applications where self-discharge matters, like emergency gear and smoke detectors. When a manual specifies a battery type, follow it.
Do batteries expire?
Disposable batteries have a best-before date printed on the packaging, reflecting how long the manufacturer guarantees stored performance. A battery does not die on that date, but capacity slowly declines in storage. Buy sealed stock with the date visible, store it cool and dry, and use older packs first. Our listings state the printed date where one exists.
Should I refrigerate batteries?
No. Manufacturers recommend storage at normal room temperature in a dry place. Refrigeration adds condensation risk and no meaningful benefit for modern batteries. Just keep them out of hot places like cars in summer.
What should I do with dead batteries?
Rules vary by state and city. Some areas accept alkalines in household trash while others require drop-off recycling, and rechargeables should always go to battery recycling points, which many hardware and electronics stores host. Check your local guidelines rather than assuming.
Shop at Big Deals Bay
Related reading: Energizer batteries and chargers guide and Best deals on electronics and home goods online.
