Every battery carries clues about its type, chemistry, and size right on its label or casing. You just need to know where to look and what the codes mean. Whether you’re replacing a household AA, matching a tiny coin cell, identifying a car battery, or finding the right laptop battery, the identification method is slightly different for each.
Reading Household Battery Labels
Standard household batteries (AA, AAA, C, D, 9V) are the easiest to identify. The size name is almost always printed in large text on the wrapper. What’s less obvious is the chemistry, which determines whether the battery is single-use or rechargeable and affects its voltage and lifespan.
Look for these chemistry keywords on the label:
- Alkaline or Carbon-Zinc: Single-use. These are the standard batteries you grab off a store shelf. The label will say “alkaline” and often “Do Not Recharge.”
- Lithium (Li): Single-use, but longer lasting and lighter than alkaline. The wrapper typically says “lithium” prominently.
- Nickel-Metal Hydride (Ni-MH): Rechargeable. These list a capacity in milliamp-hours (mAh), such as “2000 mAh,” which tells you how long they last per charge.
- Nickel-Cadmium (Ni-Cd): Rechargeable. An older technology, less common now, but still found in some power tools.
If the battery shows a capacity rating in mAh, it’s rechargeable. Single-use batteries almost never list this number. And if you see “Do Not Recharge” anywhere on the wrapper, take it seriously: charging an alkaline battery can cause it to leak or rupture.
Decoding IEC and ANSI Codes
Beyond the familiar AA or AAA name, batteries carry standardized codes set by two organizations: ANSI (American National Standards Institute) and the IEC (International Electrotechnical Commission). These codes pack the battery’s chemistry, shape, and dimensions into a short string of letters and numbers.
The IEC system is the one you’ll encounter most often on packaging and spec sheets. It works like this: the first letter indicates chemistry, the second letter indicates shape, and the numbers that follow indicate size. For example, “LR6” is the IEC code for a standard alkaline AA battery. The “L” means alkaline, the “R” means round (cylindrical), and “6” is the size designation for AA. A plain “R6” with no leading letter is a carbon-zinc battery in the same AA size.
The ANSI system works differently. Its first letter identifies the shape, followed by a number for size, with additional letters sometimes added for chemistry and terminal type. You’ll see ANSI codes less frequently on consumer packaging, but they show up in technical documentation and cross-reference charts.
When shopping for replacements, you don’t need to memorize these systems. Just match the full code printed on your old battery. If a spec sheet lists “LR6” as compatible, any battery labeled LR6 will fit regardless of brand.
Identifying Coin and Button Cells
Small disc-shaped batteries are where identification gets tricky, because dozens of sizes look nearly identical. The letter prefix on a coin cell tells you exactly what chemistry is inside:
- CR: Lithium. Delivers 3 volts. The most common type, used in watches, key fobs, and medical devices.
- LR: Alkaline. Delivers 1.5 volts.
- SR: Silver oxide. Delivers 1.55 volts. Common in watches and precision instruments.
The numbers after the prefix encode the physical dimensions. For a CR2032, “20” means 20 millimeters in diameter and “32” means 3.2 millimeters thick. A CR2025 is the same diameter but thinner at 2.5 mm. Getting the dimensions wrong by even a fraction of a millimeter can mean a battery that doesn’t fit or doesn’t make proper contact.
Here’s a common source of confusion: an LR44 and a CR equivalent are not interchangeable despite looking similar. The LR44 is 1.5 volts while a CR equivalent is 3 volts. Using the wrong chemistry can damage your device. Always match the full code, not just the number portion. The battery known as LR44 is the same as what various manufacturers call A76, AG13, or 357, so if you see any of those on a cross-reference chart, they’re all the same alkaline cell.
Telling Car and Lead-Acid Batteries Apart
Vehicle and backup-power batteries come in three main types, and telling them apart matters for both performance and maintenance.
Flooded (wet cell) batteries are the most common and least expensive. The giveaway is removable caps on top. These caps cover individual cells that you can open to check or top off the liquid electrolyte inside. If you see caps you can pry off or unscrew, it’s a flooded battery.
AGM (Absorbed Glass Mat) batteries are sealed with no removable caps. The electrolyte is held in fiberglass mats between the lead plates, making them spill-proof. The label will typically say “AGM” or “Absorbed Glass Mat.” They’re increasingly common in newer vehicles, especially those with start-stop systems.
Gel cell batteries are also sealed and look similar to AGM from the outside. The difference is that the electrolyte is mixed with silica to form a thick gel. The label will usually say “Gel” or “Gel Cell.” They’re more common in solar setups and mobility scooters than in standard cars.
If the label has worn off, the sealed-versus-caps test is your quickest check. No caps means AGM or Gel. Caps you can remove means flooded. For the AGM vs. Gel distinction on an unlabeled battery, searching the part number printed on the casing is the most reliable method.
Using a Multimeter to Confirm Battery Type
A multimeter reading won’t tell you the exact chemistry, but it narrows down what you’re dealing with based on nominal voltage. Set your multimeter to DC voltage, touch the red probe to the positive terminal and the black probe to the negative terminal, and compare your reading to these ranges:
- 1.2V: Rechargeable Ni-MH or Ni-Cd cell
- 1.5V: Alkaline or carbon-zinc single-use cell
- 3.0V: Lithium coin cell (CR type) or lithium primary cell
- 3.4V (single cell): Lithium-ion rechargeable, fully charged
- 3.2V (single cell): Lithium iron phosphate (LiFePO4) rechargeable
- 12.7V: Fully charged 12V lead-acid battery (car, AGM, or Gel)
A fresh alkaline AA reads about 1.5 to 1.6 volts, while a fully charged Ni-MH rechargeable in the same AA size reads around 1.2 to 1.4 volts. That voltage gap is the easiest way to distinguish between the two when the label is missing. A reading of 10.5V or below on a 12V battery means it’s fully depleted.
Finding Laptop and Device Battery Specs
Internal batteries in laptops, tablets, and phones use lithium-ion (Li-Ion) or lithium polymer (LiPo) chemistry. Both are rechargeable. The challenge isn’t identifying the chemistry but finding the specific part number you need for a replacement.
For laptops, start by flipping the device over. Most Windows laptops have a sticker on the bottom with the model number near a barcode, sometimes explicitly labeled “Model.” Apple places its model number (formatted as A followed by four digits) in small text on the underside of the MacBook. The laptop model number alone is often enough to search for a compatible battery.
If you need the battery’s own part number for a more precise match, you’ll need to look at the battery itself. This means removing a back panel or popping out a removable battery. Different brands format their battery part numbers differently:
- Dell: Look for the “type” number on the battery label. There’s also a Dell Part Number (DPN) on a small white sticker within the serial number area, typically 5 characters long.
- HP: Find the model type in a box near the top of the battery label, usually 4 characters like “MU06.” Internal batteries often add “XL” at the end, making them 6 characters (like “CM03XL”). HP also prints part numbers and spare numbers in a 6-digit-hyphen-3-digit format.
- Lenovo: Batteries carry several numbers. The model name, if present, is the best one to search.
- Acer: Straightforward labeling with a model name on the battery. A separate part number and serial number label provides a backup search term.
- Apple: Battery part numbers follow the same A-plus-four-digits format as the laptop itself, but they’re found on the battery inside the unit.
For phones and tablets where you can’t easily access the battery, searching the device model number plus “battery replacement” will get you the correct part. The device model number is usually listed in the settings menu under “About Phone” or “About This Device.”